Patent Publication Number: US-9428878-B2

Title: Retaining wall system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Nos. 61/650,310, filed May 22, 2012, and 61/799,563, filed Mar. 15, 2013, which are each hereby incorporated herein by reference. 
    
    
     FIELD 
     The present application relates to embodiments of a retaining wall system. 
     BACKGROUND 
     Concrete blocks, such as used to construct retaining walls, can either be “pre-cast,” also known as “wet-cast,” or “dry-cast” blocks. Wet-cast blocks are blocks that are formed from concrete having a water-cement ratio of about 0.4 or higher. In the wet-casting process, the concrete must cure in the mold before it is removed, usually by disassembling the mold. In contrast, dry-cast blocks are formed from “zero-slump” concrete, typically using a high speed block-forming machine. 
     The main advantage of dry casting is that concrete components can be mass produced at a high rate using a block-forming machine. Since the blocks can be stripped from the mold immediately (without curing), a single mold can be used to mass produce a specific component at a much greater rate than is possible with wet casting. The size, shape and texture of dry-cast blocks however are limited by the block-forming machine and the equipment used to convey and store the blocks during the curing process, such as the pallets that support the blocks after they are removed from the mold. For example, most block-forming machines are not compatible with a mold greater than 12 inches in height. In addition, blocks greater than 24 inches in width or depth tend to cause the pallets supporting the uncured blocks (after being removed from the mold) to deflect under the weight of the blocks, allowing the blocks to deform. Thus, concrete blocks having greater dimensions typically must be manufactured using a wet-casting process. 
     The main advantage of wet-cast blocks is that the concrete has a higher density, lower porosity, and higher cement to aggregate ratio, resulting in higher freeze-thaw resistance than dry-cast blocks. As such, wet-cast blocks are preferred or required in geographic areas where the blocks frequently are exposed to freeze-thaw conditions. Another advantage of wet casting is that the blocks can be molded to have virtually any size, shape and/or texture. 
     There are several known wet-cast retaining wall systems that are used to construct structural retaining walls. These systems tend to include massive, wet-cast concrete blocks that weigh several thousands of pounds. As can be appreciated, such blocks are expensive to produce and are much more difficult to transport to a jobsite and install compared to relatively smaller dry-cast retaining wall blocks. 
     What is needed is a wet-cast retaining wall system having blocks that are easier to produce, transport and install and provide greater flexibility in the types of construction techniques that can be used to construct walls. 
     SUMMARY 
     Disclosed herein are embodiments of a retaining wall system, as well as embodiments of blocks and other devices for use in a retaining wall system. In some embodiments, a retaining wall includes a plurality of face blocks and a plurality of trunk blocks arranged in a plurality of courses of blocks. In some embodiments, a face block can include a face portion and a pair of leg portions, and each of the leg portions can be adapted to be coupled to a trunk block. In some embodiments, various block connecting devices can be used to connect blocks in a single course of blocks and various block alignment devices can be used to align blocks in adjacent courses. 
     In some embodiments, a wall block assembly comprises a face block and a trunk block. The face block can comprise a face portion and first and second leg portions formed integrally with the face portion, wherein each leg portion extends away from the face portion to a rear portion of the leg portion. The trunk block can comprise first and second end portions and an intermediate portion which interconnects the first and second end portions. The first end portion can be connected to the rear portion of the first leg portion and the second end portion can be connected to the rear portion of the second leg portion. The face portion, first leg portion, second leg portion, and the trunk block define an enclosed space in a horizontal plane to receive backfill material. The face block and the trunk block can comprise either wet-cast or dry-cast concrete. 
     In particular embodiments, the wall block assembly can further comprise a first connecting element connecting the rear portion of the first leg portion of the face block to the first end portion of the trunk block, and/or a second connecting element connecting the rear portion of the second leg portion of the face block to the second end portion of the trunk block. Each of the rear portions of the first and second leg portions of the face block can comprise two ridges in an upper surface of the leg portion and a slot defined between the two ridges adapted to receive a respective connecting element. Each of the first and second end portions of the trunk block can comprise at least one slot in an upper surface of the end portion. The first connecting element can be disposed in the slots of the first leg portion and the first end portion of the trunk block, and the second connecting element can be disposed in the slots of the second leg portion and the second end portion of the trunk block. 
     In some embodiments, the first connecting element comprises first and second end portions, with the first end portion being configured to engage at least one of the ridges of the first leg portion, and the second end portion being configured to engage an adjacent surface of the trunk block as to resist lateral separation of the face block and the trunk block. The second connecting element similarly can comprise first and second end portions configured to engage adjacent surfaces of the second leg portion and the trunk block. In some embodiments, each of the rear portions of the first and second leg portions of the face block can further comprise a respective pocket defined between the two ridges wherein the pocket has a width which is greater than a width of the slot defined between the two ridges. 
     In some embodiments, a wall block assembly comprises a face block comprising a face portion and first and second leg portions formed integrally with the face portion, wherein each leg portion extends away from the face portion to a rear portion of the leg portion. The wall block assembly can further comprise a first trunk block comprising first and second end portions and an intermediate portion which interconnects the first and second end portions. The first end portion is coupled to the rear portion of the first leg portion. A second trunk block comprises first and second end portions and an intermediate portion which interconnects the first and second end portions. The first end portion of the second trunk block can be coupled to the rear portion of the second leg portion of the face block. 
     In some embodiments, the first and second leg portions of the face block extend from quarter points of the face portion of the face block. In some embodiments, a wall block assembly can further comprise first and second upper pockets formed in a top surface of the face block and first and second lower pockets formed in a bottom surface of the face block. The pockets can be situated at respective quarter points of the face block. When forming courses of a wall, the first and second upper pockets receive the lower portions of respective block-connecting elements and the first and second lower pockets are placed over the upper portions of respective block-connecting elements of blocks in a lower course. In other embodiments the face block can be formed with integral nubs, or projections, formed in the upper surface of the face block, rather than first and second upper pockets. The nubs are configured to be positioned in the lower pockets of blocks in a vertically adjacent course. 
     In some embodiments, a method of assembling a wall block assembly comprises positioning a face block in a desired position, wherein the face block comprises a face portion and first and second leg portions formed integrally with the face portion, wherein each leg portion extends away from the face portion to a rear portion of the leg portion. A trunk block is placed in a desired position relative to the face block such that the rear portion of the first leg portion is adjacent to a first end portion of the trunk block and the rear portion of the second leg portion is adjacent to a second end portion of the trunk block. The method can further comprise connecting the rear portion of the first leg portion to the first end portion of the trunk block and connecting the rear portion of the second leg portion to the second end portion of the trunk block. 
     In some embodiments, the rear portion of the first leg portion of the face block includes a slot, the first end portion of the trunk block includes a slot, and the act of connecting the rear portion of the first leg portion to the first end portion of the trunk block comprises inserting a connecting element into the slot in the rear portion of the first leg portion and the slot of the first end portion of the trunk block. In some embodiments, the rear portion of the second leg portion of the face block includes a slot, the second end portion of the trunk block includes a slot, and the act of connecting the rear portion of the second leg portion to the second end portion of the trunk block comprises inserting a connecting element into the slot in the rear portion of the second leg portion and the slot of the second end portion of the trunk block. 
     The foregoing and other features and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a top plan view of a block assembly, according to one embodiment. 
         FIG. 2  is a top plan view of the face block of the block assembly of  FIG. 1 . 
         FIG. 3  shows a side elevation view of the face block of the block assembly of  FIG. 1 . 
         FIG. 4  is a top plan view of a trunk block of the block assembly of  FIG. 1 . 
         FIG. 5  is a top plan view of an anchor block of the block assembly of  FIG. 1 . 
         FIG. 6  is a top plan view of a corner face block that can be used in the block assembly of  FIG. 1 . 
         FIG. 7  is a side cross-sectional view of a wall constructed from multiple block assemblies of the type shown in  FIG. 1 . 
         FIG. 8  is a top plan view of a wall constructed from multiple block assemblies of the type shown in  FIG. 1 . 
         FIG. 9  is a top plan view of a convex curved wall constructed from multiple block assemblies of the type shown in  FIG. 1 . 
         FIG. 10  is a top plan view of a block assembly, according to another embodiment. 
         FIGS. 11-16  are various views of a block-connecting element that can be used to interconnect two blocks in adjacent courses. 
         FIG. 17  is a top plan view of a pilaster, according to one embodiment. 
         FIG. 18  is a top plan view of a pilaster, according to another embodiment. 
         FIG. 19  is a top plan view of another embodiment of a block assembly. 
         FIG. 20  is a side elevation view of a wet-cast concrete block, according to another embodiment. 
         FIG. 21  is a rear elevation view of the block shown in  FIG. 20 . 
         FIG. 22  is a top plan view of a vertical reinforcing member of the block shown in  FIG. 20 . 
         FIG. 23  is a side view illustrating the construction of a wall made from blocks of the type shown in  FIG. 20 . 
         FIG. 23A  is a top plan view of a soil reinforcing strap shown in  FIG. 23 . 
         FIG. 24  is a top plan view of a wet-cast concrete block, according to another embodiment, having a mechanism for coupling soil reinforcing straps to the block. 
         FIG. 25  is a side elevation view of the block shown in  FIG. 24 . 
         FIG. 26  is a top plan view similar to  FIG. 24  showing an alternative mechanism for coupling soil reinforcing straps to the block. 
         FIG. 27  is a side view of the coupling mechanism and the soil reinforcing strap shown in  FIG. 26 . 
         FIG. 28  is a side view of the coupling mechanism of  FIG. 26 , showing an alternative way of securing a soil reinforcing strap to the coupling mechanism. 
         FIGS. 29-32  are various views of a face block, according to one embodiment. 
         FIGS. 33-36  are various views of a trunk block, according to one embodiment. 
         FIGS. 37-40  are various views of a block assembly comprising the face block of  FIGS. 29-32  and the trunk block of  FIGS. 33-36 , according to one embodiment. 
         FIGS. 41-43  are various views of two courses of a curved retaining wall formed from multiple block assemblies of the type shown in  FIGS. 37-40 . 
         FIGS. 44-47  are various views of another embodiment of a block assembly comprising the face block of  FIGS. 29-33  and two of the trunk block of  FIGS. 33-36 . 
         FIGS. 48-51  show different embodiments of a connecting element being used to connect a face block and a trunk block. 
         FIG. 52  shows a top plan view of a course of a wall comprising a plurality of blocks, according to one embodiment. 
         FIG. 53  shows a top plan view of a course of a wall comprising a plurality of blocks, according to another embodiment. 
         FIG. 54  shows a top plan view of a course of a wall comprising a plurality of blocks, according to another embodiment. 
         FIG. 55  shows a top plan view of a course of a wall comprising a plurality of blocks, according to another embodiment. 
         FIG. 56  shows a top plan view of a wall block, according to one embodiment. 
         FIG. 57  shows a perspective view of a block alignment device, according to one embodiment. 
         FIG. 58  shows a top plan view of the block alignment device of  FIG. 57 . 
         FIG. 59  shows the block alignment device of  FIGS. 57-58  positioned so as to establish a positive batter between two blocks in adjacent courses. 
         FIG. 60  shows the block alignment device of  FIGS. 57-58  positioned to establish a vertical alignment between two blocks in adjacent courses. 
     
    
    
     DETAILED DESCRIPTION 
     A retaining wall system, according to one embodiment, comprises a plurality of interlocking concrete blocks that are configured to be used together in forming block assemblies laid side-by-side in courses of a wall.  FIG. 1  shows a first block assembly  10 , according to one embodiment. The block assembly  10  comprises a face block  12 , one or more trunk blocks  14  connected to the face block, and one or more anchor, or tail, blocks  16  connected to each of the trunk blocks. Additional blocks can be added to an assembly to increase the depth of the assembly, as further described below. 
     As shown, the face block  12  has a face or front surface  18  that is exposed in the front surface of a wall. The front surface  18  can be formed with any of various desired textures and/or configurations that enhance the appearance of the block. In particular embodiments, the face block  12  is a wet-cast block, which allows virtually any pattern or surface design to be molded into the front surface  18  of the block. In other embodiments, the face block  12  is a dry-cast block formed from a conventional block-forming machine. Where a block-forming machine is used, the mold can be equipped with components that texture the front surface  18  of the block as it is stripped from the mold to provide a texture to the front surface that resembles a split block. Once such process for texturing dry-cast blocks is disclosed in U.S. Pat. No. 7,100,886, which is incorporated herein by reference. In addition, the front face  18  of the face block  12  is shown as being straight, although other configurations are possible with either wet casting or dry casting. For example, the front face  18  can have a convex curved surface, a single-faceted configuration, a two-faceted configuration comprising two angled surfaces, or a three-faceted configuration comprising a center facet and two angled side surfaces extending rearwardly from respective sides of the center facet. 
     Each trunk block  14  is attached to the rear face  20  of the face block  12  desirably at about the quarter points of the face block (i.e., at locations along the width of the block  12  that are spaced inwardly from the sides a distance equal to about ¼ the width of the block). Each trunk block  14  extends perpendicularly from the face block  12  in the rearward direction. Each anchor block  16  is attached to the rearward end of a respective trunk block  14  so that it is parallel to the face block  12  and perpendicular to the trunk block, with the trunk block being attached to the anchor block at a vertical medial junction of the anchor block. 
     When constructing a wall, the face block  12 , trunk blocks  14 , and anchor blocks  16  are assembled to provide a block assembly  10 , as depicted in  FIG. 1 . In the interconnected state, the components of the assembly  10  may not be disconnected or separated in any lateral direction (i.e., side-to-side or front-to-back in a wall) without breakage. The block components in the illustrated embodiment are not merely held in place by frictional forces and the presence of adjacent unconnected blocks. Each block component is securely mechanically engaged to at least one other adjacent block component of the same block assembly  10 . 
     In particular embodiments, the face block  12 , trunk blocks  14 , and anchor blocks  16  are interconnected by dovetail joints so that they may be separated only by vertically sliding one block component with respect to an attached block component. A dovetail joint may be formed in any of a wide variety of geometries as long as the block components are connected against lateral separation. Dovetail joints generally have a male key or tongue  24  that mates with a female slot or groove  22 . Typically, the tongue is wider at some position toward its free end than at another position closer to its root. The female groove  22  is configured to closely conform to the male shape of a tongue  24 . In the illustrated embodiment, the face block  12  and anchor block  16  define the vertical grooves  22 , which are generally trapezoidal, with the face being wider than the aperture at the surface of each block. Compatible male tongues  24  are integrally formed on the ends of the trunk block  14 , with the free end being wider than the root. The grooves  22  on the face block  12  can be formed in respective projections  26  extending vertically the height of the block and rearwardly from the rear face  20 . In other embodiments, the grooves  22  can be formed directly in the rear face  20  of the block (such as with the corner block  200  shown in  FIG. 6 ). 
     Although less desirable, the face block and the trunk blocks can be formed as a single unit that is connected to a separable anchor block(s). In a similar manner, each trunk block and a respective anchor block can be formed as a single unit that is connected to a separable face block. 
     The groove  22  desirably does not pass entirely through the block, but terminates at an upwardly facing lower surface  28 . Thus, the lower portion of the face block  12  is solid and unbroken by the groove  22 , thereby increasing the strength of the block and decreasing the risk of breakage at the groove  22 . The lower surface  28  desirably is sloped such that it faces generally upward and rearwardly of the block. 
       FIG. 4  shows the trunk block  14  with a male tongue  24  at each end of the block. Each tongue  24  desirably has a sloped lower surface corresponding to the lower surface  28  of a corresponding female groove  22  in the face block  12  or an anchor block  16 .  FIG. 5  is a top view of an anchor block  16 . The illustrated anchor block  16  desirably is formed with a female groove  22  centrally defined on the front and rear faces according to the configuration of the grooves  22  formed in the face block  12 . The grooves  22  are oriented back-to-back and spaced apart by a solid web  30  of block material to provide adequate strength. The anchor block  16  also may be formed with a male tongue  24  on each end, as depicted in  FIG. 5 . This allows the anchor block  16  to be optionally used as a trunk block to provide a block assembly having an overall depth that is shorter than the depth of the block assembly  10  shown in  FIG. 1 . The tongues  24  and grooves  22  can all be similarly tapered along their vertical lengths so that each dovetail joint is secured against excess motion and slippage by the respective tongue  24  being wedged into the respective groove  22 . 
     Referring to  FIGS. 1-3 , the face block  12  can be formed with a channel  32  in its lower surface  34 . The channel  32  extends parallel to the width of the block and desirably extends the entire block width, thereby opening at the sides  36  of the block. The face block  12  can also be formed with one or more alignment nubs, or projections,  38  that are configured to be received by and extend into a channel  32  of an overlying block in a wall. In other words, when face blocks  12  are stacked on top of each other to form the courses of a wall, the alignment nubs  38  of a block extend into a channel  32  of an overlying block. The channel  32  and the nubs  38  serve two main purposes: they assist in achieving the desired alignment of blocks in the vertical direction and serve as a connection between two vertically adjacent blocks that resists lateral shear forces acting on the blocks. The nubs  38  desirably are offset toward the rear face  20  of the face block in order to create a set back or positive batter wall. Referring to  FIG. 7 , for example, a wall comprises multiple courses  50   a ,  50   b ,  50   c ,  50   d ,  50   e . As can be seen with respect to the first and second courses  50   a ,  50   b , respectively, the nub  38  of the face block  12  in the first course  50   a  extends into the channel  32  of the face block  12  of the second course. Since the nub is offset toward the rear of the block, the face block  12  of the second course  50   b  is slightly set back with respect to the face block  12  of the first course  50   a , creating a positive batter. 
     For purposes of illustration, the face block  12  is also shown with a channel  40  in its upper surface  42 . The channel  40  is adapted to receive a separate block-connecting element  100  ( FIGS. 11-16 ) that can be used as an alignment device and for interconnecting vertically adjacent blocks, in lieu of or in addition to the alignment nubs  38 . The use of block-connecting elements  100  in the construction of a wall is described in detail below. Where alignment nubs  38  are provided, the channel  40  in the upper surface and the block-connecting elements  100  can be optional. Conversely, where block-connecting elements  100  are used, the nubs  38  can be optional. 
     In the embodiment of  FIG. 1 , the trunk blocks  14  are longer than the anchor blocks  16 , although this need not be the case.  FIG. 10 , for example, shows a block assembly  80  in which the trunk blocks  14  and the anchor the blocks  16  have the same length. Thus, the block assembly  80  has a depth D 1  that is less than the depth D 1  of the block assembly  10  shown in  FIG. 1 . Shorter trunk blocks may be utilized when less stabilization is required. In particular embodiments, a single block can be utilized as a trunk block and an anchor block, so long as it is provided with male tongues  24  on its opposite ends (for use as a trunk block) and female grooves  22  on opposite sides (for use as an anchor block). 
       FIG. 6  shows an example of a corner face block  200  that can be used in place of a standard face block  12  in the block assembly. The corner block  200  can be used to form 90-degree corners in a wall. The corner block  200  has a front face  202 , a rear face  204 , and opposing side walls  206  extending between respective ends of the front face and the rear face at right angles with respect to the front and rear faces. The rear face  204  can be formed with a centrally located female groove  22  adapted to receive the male tongue  24  of a trunk block  14 . The upper surface  208  of the corner block can be formed with a main channel  210  extending lengthwise of the block and two side channels  212  extending from the ends of the main channel to the rear face  204  of the block. The block  200  can also be formed with similar channels (not shown) in the lower surface of the block. The channels in the upper and lower surfaces can be used with a block-connecting element (e.g., block-connecting element  100  of  FIGS. 11-16 ) to interconnect a corner face block  200  with other corner face blocks or other standard face blocks  12  in an overlying or underlying course. Alternatively, the corner face block  200  optionally can be formed with nubs  38  on its upper surface (similar to block  12 ) that are received in the channel in the lower surface of another block  200  or a block  12 . 
       FIG. 8  shows the construction of a wall using multiple block assemblies  10 . As shown, the block assemblies  10  are placed side-by-side with respect to each other in each course so that their trunk blocks  14  are generally parallel and the face blocks  12  are positioned side-by-side in a continuous line. Each pair of trunk blocks  14  of a single block assembly  10  defines a generally rectangular void or chamber  44  suitable for filling with a suitable backfill material (desirably aggregate and/or earth) to provide stability and drainage. In addition, each pair of adjacent assemblies  10  defines another generally rectangular void or chamber  46  suitable for filling with a suitable backfill material. Each chamber  46  is defined at its sides by trunk blocks  14  of adjacent assemblies  10  and at its front and rear by the face blocks  12  and anchor blocks  16  of the respective assemblies. 
     As noted above, each course may be set back by a small distance with respect to an adjacent lower course to create a slightly sloping wall face, although in other implementations the successive courses can be vertically aligned to form a vertical wall without a setback. Nonetheless, each face block  12  rests on two face blocks  12  of a lower layer in a running bond pattern, each trunk block  14  rests on a trunk block  14  of a lower layer, and each anchor block  16  rests on an anchor block  16  of a lower layer.  FIG. 8  also shows the use of a corner face block  200  in the block assemblies at the corner of the wall, which forms a 90-degree corner where the two sides of the wall meet. 
     As best shown in  FIG. 1 , the block assembly  10  has a width W 1  at the front of the assembly equal to width of the front surface  18  of face block  12  and defined between the side surfaces  36 . The block assembly  10  has a width W 2  at the rear of the assembly defined between the outermost tongues  24  of the two anchor blocks  16 . The width W 1  desirably is greater than the width W 2  so that convex curved walls may be formed by bringing together anchor blocks  16  of adjacent block assemblies  10  in a course closer than a parallel spacing would ordinarily dictate. A convex wall formed from block assemblies  10  is shown in  FIG. 9 . To form a concave wall, the anchor blocks  16  in adjacent assemblies  10  are spaced apart wider than ordinarily dictated when forming a straight wall. 
     As further shown in  FIG. 1 , each block assembly  10  has a depth D 1  defined by the distance between the front surface  18  of the front block  12  and the rear surface of anchor blocks  16 . For additional anchoring stability in a wall, particularly in the lower layers of walls having several layers, the depths of the assemblies  10  may be extended in the rearward direction by attaching one or more additional blocks to the anchor blocks  16 . As can be seen, each anchor block  16  includes an additional groove  22  on its rear surface opposite the trunk block  14 . An additional trunk block  14  can be connected to each anchor block by inserting the tongue  24  of the additional trunk block in the unoccupied groove  22  of the anchor block. An additional anchor block  16  can be connected to each newly added trunk block by inserting the rear tongue  24  of each newly added trunk block into a groove  22  of the additional anchor block. The depth of the block assembly  10  can be extended as needed by adding additional trunk blocks and anchor blocks as needed to satisfy the engineering requirements of the wall. U.S. Pat. No. 7,503,729, which is incorporated herein by reference, further illustrates the technique of extending the depth of a block assembly. 
     As noted above, the face block  12  can be a wet-cast block, which allows the block to have dimensions much larger than a dry-cast block produced by a conventional block-forming machine. For example, in a specific embodiment, the face block  12  has a height H 1  ( FIG. 3 ) of about 24 inches, a width W 1  ( FIG. 1 ) of about 48 inches, an overall depth D 3  ( FIG. 2 ) of about 12 inches and depth D 2  ( FIG. 3 ) (between the front and rear faces) of about 10 inches. Since the face block  12  is exposed in the front surface of a wall, providing a wet-cast face block provides the additional advantage of enhanced freeze-thaw resistance compared to a dry-cast block. On the other hand, the trunk and anchor blocks need not be as massive as the face block to serve their function of anchoring the block assembly in its respective course in the wall. The anchor and trunk blocks therefore can be much smaller and lighter than the face block. Furthermore, since the anchor and trunk blocks are buried within the earth behind the face blocks, the anchor and trunk blocks are much less susceptible to damage caused by freeze-thaw conditions. As such, the anchor and trunk blocks desirably comprise dry-cast blocks that are manufactured using a conventional block-forming machine. In this manner, the block assembly  10  effectively combines the advantages of wet-cast and dry-cast blocks by utilizing a wet-cast face block and dry-cast anchor and trunk blocks. 
     In a specific embodiment, the trunk blocks  14  have a spacing S of about 24 inches, which typically corresponds to the maximum spacing allowed by most building codes. Additionally, the spacing between trunk blocks  14  of adjacent block assemblies is about 24 inches. In this manner, the block system provides for more efficient wall construction since the trunk blocks will automatically achieve the proper spacing between trunk blocks connected to the same face block  12  and between trunk blocks of adjacent block assemblies  10 . Similarly, most codes would allow for a 24-inch vertical spacing between trunk blocks. Providing a face block  12  having a height H 1  of 24 inches assists the installer achieve the proper vertical spacing between trunk blocks  14 . 
     In particular embodiments, the face block  12  has a height H 1  that is greater than the height H 2  ( FIG. 7 ) of the trunk blocks  14  and the anchor blocks  16 . In certain embodiments, the height H 1  is at least 1.3 times, at least 2.0 times, at least 3.0 times, or at least 4.0 times the height H 2 . In a specific implementation, the face block  12  has a height H 1  of about 24 inches, and the anchor and trunk blocks  14 ,  16  have a height H 2  of about 8 inches. 
     The relatively shorter anchor and trunk blocks provide several advantages, as illustrated in  FIG. 7 . As shown, face blocks, which are the tallest units, define the lower and upper limits of each course. The anchor and trunk blocks, which are shorter than the height of a course, can be positioned at any vertical location of the corresponding course to accommodate the presence of utilities or other obstacles behind the wall. For example, the anchor and trunk blocks of the first course  50   a  are shown positioned at the very bottom of the course while the anchor and trunk blocks of the second course  50   b  are shown at the very top of the course. The anchor and trunk blocks can also be positioned at any vertical position between the top and bottom of the course. 
     A single face block  12  can be connected to multiple subassemblies of trunk and anchor blocks at different vertical locations in the same course. As shown with respect to course  50   d , the face block  12  in this course is connected to an upper subassembly  52  stacked on top of a lower subassembly  54 . Each subassembly  52 ,  54  comprises at least one pair of a trunk block  14  and an anchor block  16  as described above, and desirably includes at least two pairs of a trunk block  14  and an anchor block  16  (e.g., as shown in  FIG. 1 ). In the illustrated configuration, the face block  12  is tall enough to allow yet a third subassembly of trunk and anchor blocks to be connected to the face block in a stacked arrangement with the other subassemblies. Utilizing still taller face blocks  12  would allow even more anchor and trunk subassemblies to be connected to the same face block in a stacked configuration. If desired, the trunk and anchor block subassemblies in the same course need not be stacked directly on top of each other and instead can be separated in the vertical direction by backfill material that is used to fill the voids between the trunk and anchor blocks. For example, the lowermost subassembly  54  in course  50   d  can be placed at the lowermost location in the course and separated from the uppermost subassembly  52  by a layer of backfill material. In addition, each of the upper and lower subassemblies  52 ,  54  can have one or more additional sets of trunk and anchor blocks extending rearwardly to increase the overall depth of the block assembly. 
     Notably, the backfill used to fill in the voids between the trunk and anchor blocks need not be precisely compacted and leveled during wall construction. The face blocks  12 , which define the upper and lower limits of each course, are stacked on top of each other, not the backfill material. The trunk and anchor blocks are set on top of a layer of backfill material at the bottom of the course, the top of the course, or at a location between the top and bottom of the course. Typically, a wall under construction must be backfilled and compacted every 8 inches. For a wall having 24-inch tall face blocks and 8-inch tall trunk and anchor blocks, each course is backfilled three times, allowing the trunk and anchor blocks to be set on top of a layer of backfill material at the bottom of the course, the top of the course or at the middle of the course. Since the trunk and anchor blocks do not define the upper and lower limits of the course, and instead “float” on backfill material between the upper and lower limits of the course, the backfill material need not be precisely compacted and leveled to ensure that each course of the wall is level. 
     As noted above, the face block  12  can be molded in a wet-casting process, and therefore can have relatively large height and width dimensions. Such large wet-cast blocks may be desired for a particular job site for a number of reasons. For example, the number of individual blocks and courses increases as the overall height and length of the wall increase. Thus, for very tall walls, an installer may prefer to utilize tall blocks (e.g., blocks 24 inches in height or greater) and applicable construction techniques over much smaller dry-cast blocks. A significant disadvantage of large wet-cast blocks, of course, is that they are difficult to store and transport to a job site due to their massive size. Advantageously, the use of anchor and trunk blocks, which add depth to the block assembly and effectively anchor the block assemblies in their respective courses, can effectively minimize the overall size and weight of the face block  12 . In other words, the face block  12  can have a depth D 3  ( FIG. 2 ) that is much less than the height H 1  and width W 1  due to the presence of the anchor and trunk blocks, which effectively minimizes the overall size and weight of the block. Thus, the face block can satisfy the need of the installer to have a block with large height and width dimensions, yet the overall size and weight is reduced, which reduces manufacturing, storage and transportation costs and facilitates installation of the blocks. 
     In one specific implementation, for example, the face block  12  can have a height H 1  of about 24 inches, a width W 1  of about 48 inches, a depth D 3  of about 12 inches (measured from the front face to the rear surface of projections  26 ), and weighs about 970 lbs. Comparatively, a block having the same height and width dimensions that does not utilize anchor and trunk blocks for stabilization typically would require at least twice the depth and have at least twice the weight. 
     Referring again to  FIG. 7 , a wall can include a tie-back sheet  56  (also known as geogrid) to reinforce one or more courses of the wall. As shown, the tie-back sheet is positioned between two courses and extends rearwardly into the backfill material behind the wall. The tie-back sheet  56  typically comprises a flexible, polymeric sheet of material (e.g., a sheet of polyester) having preformed openings or strips of material assembled in a grid-like pattern. The front edge of the tie-back sheet  56  can be placed between the upper surface of one face block  12  and the lower surface of an overlying face block  12  and is held in place by the weight of the overlying face block. The nubs  38  of the lower face block can be positioned in openings in the front edge portion of the tie-back sheet  56  to assist in retaining the tie-back sheet in place. Where a tie-back sheet is used between two courses, the trunk and anchor blocks of the lower course (course  50   b  in this case) can be placed at the top of their respective course while the trunk and anchor blocks of the upper course (course  50   c  in this case) can be placed at the bottom of their respective course. In this manner, the tie-back sheet is also frictionally retained by the weight of the trunk and anchor blocks in course  50   c  bearing on the trunk and anchor blocks in course  50   b.    
     In some installations, some or all of the courses of a wall can be constructed from face blocks  12  without any trunk and anchor blocks. A tie-back sheet  56  typically is installed between selected adjacent courses to stabilize the wall. Providing face blocks  12  with a depth D 3  of at least 10 inches and preferably about 11-12 inches provides sufficient block surface area for contacting a tie-back sheet  56  placed between courses and sufficient block depth to allow various face patterns or geometries to be cast into the front surface of the block. 
     During construction of a wall, the voids or chambers  44 ,  46  formed by the blocks assemblies  10  typically are backfilled with aggregate material (e.g., crushed stone) to ensure sufficient drainage behind the front of the wall, while the space behind the block assemblies  10  and embankment is backfilled with soil. It is known to separate zones containing aggregate material and soil with a sheet of flexible material commonly referred to as filter fabric, typically made of porous fabric material. Referring to  FIG. 7 , the anchor blocks  16  provide a convenient support on which a separating sheet  60  can be placed or draped to separate the zone of each course filled with aggregate (within voids  44 ,  46 ) and the zone behind the block assemblies  10  which is filled with soil. The horizontal spacing between adjacent anchor blocks  16  within the same course (e.g., about 12 inches) is such that anchor blocks can support the separating sheet  60  without it tearing. 
     As noted above, the face blocks  12  can be formed without nubs  38  and instead can be interconnected to each other using separate block-connecting elements, which can be made of a suitable polymer, composite (e.g., fiberglass or carbon fiber composite), metal, or various other suitable materials. In use, a block-connecting element is placed in the channel  40  of a face block  12 . A face block  12  in the next successive course is placed over the face block in the course below such that an upper portion of the block-connecting element extends into the channel  32  of the face block in the next successive course. 
       FIGS. 11-16  show one example of a block-connecting element that can be used with the block assembly  10  in the construction of a wall. The block-connecting element  100  can be referred to as a “three-way” block-connecting element (or “three-way” alignment plug) because it can be positioned in three different positions within an alignment core of a block to permit vertical, set forward, or set back placement of blocks in a course relative to the blocks in an adjacent lower course, as further described below. 
     As shown in  FIGS. 11-16 , the block-connecting element  100  comprises a lower portion, or projection,  102 , an upper portion, or projection,  104 , and an intermediate flange portion  106  separating the upper and lower portions. The lower portion  102  can be formed with vertically extending, spaced-apart ribs  108  that extend outwardly from one or more sides of the lower portion (e.g., in the illustrated embodiment, the ribs  108  are formed on three sides of the lower portion). The ribs  108  desirably taper in height extending in a direction from the flange portion  106  to the lower end of the lower portion  102 . When inserted into a block, the ribs  108  can contact one or more inner surfaces of a core or channel of the block to assist in frictionally retaining the block-connecting element within the block. Likewise, the upper portion  104  can be formed with vertically extending, spaced-apart ribs  110  that extend outwardly from one or more sides of the upper portion (e.g., in the illustrated embodiment, the ribs  110  are formed on three sides of the upper portion). The ribs  110  desirably taper in height extending in a direction from the flange portion  106  to the upper end of the upper portion  104 . When inserted into a block, the ribs  110  can contact one or more inner surfaces of a core or channel of the block to assist in frictionally retaining the block-connecting element within the block. 
     The upper portion  104  is horizontally offset from the lower portion  102 ; thus, the upper portion  104  is located closer to a forward edge  112  of the flange portion  106  and the lower portion  102  is located closer to a rear edge  114  of the flange portion  106 . In the illustrated embodiment, the upper portion  104  is aligned with the forward edge  112  while the lower portion  102  is spaced slightly from the rear edge  114  by a distance d. 
       FIG. 2  shows the three positions of the block-connecting element  100  in a face block  12 . Block-connecting element  100 ′ is in a neutral position in which the upper portion  104  is vertically aligned with the channel  40  for constructing a substantially vertical wall (all of the courses are vertically aligned without a batter). Although not shown, the upper surface  42  of the block can be formed with a shallow recess on either side of the channel  40  so that the flange portion  106  sits flush or slightly below the upper surface  42  of the block. When constructing a vertical wall, one or more block-connecting elements  100  are positioned in a neutral position in the channel  40  of each face block  12  of the previously laid course. When forming the next course of blocks, each face block  12  being added to the wall is placed over two face blocks in the adjacent lower course in a running bond such that the upper portion  104  of each block-connecting element extends upwardly into a channel  32  of a block in the newly formed course. Because the lower portion  102  and the upper portion  104  of each block-connecting element  100  are vertically aligned with respective channels of a block below and of a block above, the blocks interconnected by the block-connecting elements are vertically aligned.  FIG. 7 , for example, shows course  50   d  vertically aligned with course  50   e.    
     Block-connecting element  100 ″ in  FIG. 2  is in a forward position in which the upper portion  104  is offset from the channel  40  toward the front face  18  of the block for constructing a wall with negative batter. When constructing a wall with a negative batter, one or more block-connecting elements  100  are positioned in a forward position in the channel  40  of each face block  12  of the previously laid course. When forming the next course of blocks, each face block  12  being added to the wall is placed over two face blocks in the adjacent lower course in a running bond such that the upper portion  104  of each block-connecting element extends upwardly into a channel  32  of a block in the newly formed course. Because the upper portion  104  of each block-connecting element  100  is offset from the channel  40  of the previously laid course in a forward direction, the blocks of the newly formed course are set forward with respect to the blocks of the adjacent lower course. 
     Block-connecting element  100 ′″ in  FIG. 2  is in a rearward position in which the upper portion  104  is offset toward the rear of the face block for constructing a wall with positive batter. When constructing a wall with a positive batter, one or more block-connecting elements  100  are positioned in a rearward position in the channel  40  of each face block  12  of the previously laid course. When forming the next course of blocks, each face block being added to the wall is placed over two blocks in the adjacent lower course in a running bond such that the upper portion  104  of each block-connecting element extends upwardly into a channel  32  of a block in the newly formed course. Because the upper portion  104  of each block-connecting element  100  is offset from the channels  40  of the previously laid course in a rearward direction, the blocks of the newly formed course are set back with respect to the blocks of the adjacent lower course.  FIG. 7 , for example, shows course  50   c  set back relative to course  50   b.    
       FIG. 17  shows an example of the construction of a pilaster or column using the blocks described above. In this example, the pilaster is formed from two corner blocks  200  placed back-to-back and interconnected by a block  16 . The male tongues  24  on the opposite ends of the block  16  are received in respective grooves  22  in the blocks  200 . Additional layers of blocks  200  interconnected by a block  16  can be stacked on top of each other to achieve the desired height of the pilaster. The space between the blocks  200  is sufficient to allow the ends of wall sections  302 ,  304 , each comprising stacked courses of face blocks  12 , to extend into the pilaster. 
       FIG. 18  shows another example of a pilaster construction. In this example, the pilaster is formed from two blocks  200  placed back-to-back and interconnected by a block  14 . The spacing between the blocks  200  is sufficient to allow the ends of wall sections  306 ,  308  to extend into the pilaster. Each wall section  306 ,  308  comprises stacked layers of two rows of face blocks  12 . The wall construction shown in  FIG. 18  can be used for a free-standing wall or fence (where both sides of the wall are visible). 
       FIG. 19  shows a block assembly  310  that can be a section of a free-standing wall or fence. The assembly  310  includes two face blocks  12  placed back-to-back and interconnected by two blocks  16 . A course of a wall can be formed by placing multiple block assemblies  310  side-by-side with respect to each other. Course  50   e  in  FIG. 7  comprises block assemblies  310 , which can extend into the embankment behind the wall or can be a barrier wall placed on top of the embankment. 
       FIGS. 20 and 21  show a wet cast block  400 , according to another embodiment. The block  400  comprises upper and lower surfaces  402  and  404 , respectively, opposed front and rear surfaces  406  and  408 , respectively, and opposed side surfaces  410  extending from respective ends of the front surface to respective ends of the rear surface. The lower surface  404  is formed with a channel  412  that desirably extends the entire width of the block (the width being measured from one side surface to the other). The upper surface  402  is formed with one or more recessed portions or pockets  414  (two in the illustrated embodiment) spaced apart from each other in the direction of the width of the block. Each recessed portion  414  is defined by a forward wall  416  and two opposed side walls  418 , and is open at the rear surface  408  of the block. 
     The block  400  is formed with a forward row of one or more vertical reinforcement members  420  (two in the illustrated embodiment) spaced apart from each in the direction of the width of the block and a rearward row of one or more vertical reinforcement members  422  (two in the illustrated embodiment). The rear reinforcement members  422  desirably are aligned directly behind respective forward reinforcement members  420  as shown. The forward reinforcement members  420  desirably extend substantially the entire height of the block from the upper surface  402  to a location just above the channel  412 . Each forward reinforcement member  420  has an upper portion  424  that extends upwardly into the recessed portion  418  but does not extend above the upper surface  402  of the block. The rear reinforcement members  422  can be much shorter than the forward reinforcement members  420 ; for example, in the illustrated embodiment, the rear reinforcement members  422  are about one fifth to about one third the overall height of the block. Each rear reinforcement member  422  has an upper portion  426  that extends upwardly into the recessed portion  418  but does not extend above the upper surface  402  of the block. The height of the forward reinforcement members  420  and the rear reinforcement members  422  within the block can be varied in other embodiments. For example, in one implementation, the rear reinforcement members  422  can be longer than the forward reinforcement members  420  and therefore extend closer to the lower surface of the block than the forward reinforcement members  420 . 
     The vertical reinforcement members desirably are made of a suitable metal, such as steel, although any suitable materials useful for reinforcing concrete can be used. In particular embodiments, the reinforcement members comprises square or rectangular tubing (as shown in  FIG. 22 ), although other types of elongated reinforcing members can be used, such as a length of pipe, a solid rod, or a length of channel having any of various cross-sections. An advantage of using a tubular, or hollow, member is that a post-tensioned member (e.g., an elongated cable or rod) can be inserted vertically through vertically aligned reinforcement members  420  of multiple blocks stacked on top of each other. The upper and lower ends of the post-tensioned member can be secured with plates at locations below the lowermost course and above the uppermost course and placed in tension so as exert a compressive force to the blocks between the ends of the post-tensioned member. In a specific embodiment, the vertical reinforcement members  420 ,  422  comprise tubing having a rectangular cross-section (as depicted in  FIG. 22 ) having a length L of about 1.5 inches and a width W 3  of about 1.0 inch, although these dimensions can vary. Each of the vertical reinforcement members desirably is positioned such that the length L of the cross-section is parallel to the front surface  406  of the block. 
     As best shown in  FIG. 21 , the vertical reinforcement members  420 ,  422  can be placed on the “quarter points” of the block, which are locations spaced from respective side surfaces  410  a distance equal to one-quarter the width of the block (the total distance between side surfaces  410 ). 
     The block  400  can also include a first set of horizontally disposed reinforcement members  432  and a second set of horizontally disposed reinforcement members  434 . The horizontal reinforcement members  432 ,  434  can be conventional steel rebar or any other suitable reinforcement members useful for reinforcing concrete. As best shown in  FIG. 21 , reinforcement members  432  extend in the direction of the width of the block. As best shown in  FIG. 20 , reinforcement members  434  extend in the direction of the depth of the block. 
     The block  400  can be formed by placing the vertical and horizontal reinforcement members  420 ,  422 ,  432 ,  434  in a mold having a mold cavity sized and shaped to form the block in a wet-cast process. The forward vertical reinforcement members  420  can be supported on top of a portion of the mold that forms the channel  412  of the block. The horizontal reinforcement members  432 ,  434  can be supported by the vertical reinforcement members  420 , such as with conventional rebar ties or by inserting reinforcement members  432 ,  434  through corresponding openings in the vertical reinforcement members  420 . The rear vertical reinforcement members  422  can be supported on respective horizontal reinforcement members  434 , such as with conventional rebar ties or by inserting respective reinforcement members  434  through corresponding openings in the vertical reinforcement members  422 . After the reinforcement members are in place, concrete can be poured into the mold and allowed to cure, after which the hardened, cured block can be removed from the mold. 
     The upper portions  424 ,  426  of the vertical reinforcement members can serve as attachment locations for lifting elements for lifting the block. For example, a bolt  436  can be secured to each adjacent pair of vertical reinforcement members  420 ,  422 , such as by welding the bolt  436  to the upper portions  424 ,  426 , or by inserting the bolt  436  through corresponding openings in the upper portions  424 ,  426  and securing the ends of the bolt with nuts  438  as depicted in  FIG. 20 . The block  400  can be lifted and relocated by securing a lifting device (e.g., a chain with a hook or lifting straps) to each of the bolts  436  and to a vehicle or machine (e.g., such as the tines of a forklift or backhoe) that is capable of lifting the weight of the block. In this manner, the block can be easily lifted and relocated, such as when positioning the block for shipment or positioning the block within a course of a wall during construction of the wall. 
     The upper portions  424 ,  426  of the vertical reinforcement members can also be used as part of a block alignment and connection system for aligning and interconnecting vertically adjacent blocks. In the illustrated embodiment, for example, the upper portions  424 ,  426  are configured to receive a block-connecting element  440  in the form of a cap that fits on top of the upper portions  424 ,  426  of the vertical reinforcement members. The block-connecting element  440  is sized such that when placed on the upper portion of a vertical reinforcement member it can extend upwardly into a channel  412  in an overlying block.  FIG. 23 , for example, shows the construction of a wall having a positive batter in which a block  400   a  in a first course is connected to a block  400   b  in a second course in a set back position relative to the lower block  400   a . In this case, a connecting element  440  is placed on a rear vertical reinforcement member  422  of the lower block  400   a  and extends upwardly into the channel  412  of the upper block  400   b . It should be noted that a block connecting element  400  can be placed on each available reinforcement member  422 . In order to form a vertical wall without a batter, one or more connecting elements  440  are placed on respective forward vertical reinforcement members  420  of the lower block  400   a  such that when the channel  412  of upper block  400   b  is aligned over the connecting element, the two blocks are vertically aligned. 
     As further shown in  FIG. 23 , the vertical reinforcement members  420 ,  422  can be used as an anchor for securing a soil reinforcing strap  450  to the block  400 . The soil reinforcing strap  450  extends into the soil behind the wall to reinforce that course of the wall, much like the tie-back sheet  56  described above. As shown in  FIG. 23A , the soil reinforcing strap  450  can have an opening  452  that is sized to fit over the upper end portion of a vertical reinforcement member  420 ,  422 . The opening  452  can be also be large enough to fit over a connecting element  440  placed on a vertical reinforcement member. Alternatively, instead of an opening  452 , the forward end of the strap  450  can have a fitting or connection that fits on or connects to a vertical reinforcement member. The soil reinforcing strap  450  can be made of any of various suitable materials, such as natural or synthetic elastomers (e.g., rubber), metal (e.g., thin sheets or straps of aluminum or galvanized steel) and/or polymeric materials (e.g., synthetic fabric material or sheets of polymeric material). If non-metallic materials are used, the opening  452  can be reinforced with a metal grommet. 
     The block  400  in the illustrated embodiment is shown without any dovetail connections for connecting one or more trunk blocks  14  to the rear surface  408 . In alternative embodiments, the rear of block  400  can be formed with one or more dovetail connections, such as one or more female dovetail connections  22 , configured to engage one or more trunk blocks as described above. 
       FIGS. 24-25  show a block  500 , according to another embodiment, which desirably comprises a wet-cast block. The illustrated block  500  has an overall configuration similar to face block  12  described above. The block  500  can have overall dimensions that are the same as those described above for face block  12 . The block  500  comprises upper and lower surfaces  502  and  504 , respectively, opposed front and rear surfaces  506  and  508 , respectively, and opposed side surfaces  510  extending from respective ends of the front surface to respective ends of the rear surface. The lower surface  504  can be formed with a channel  512  that desirably extends the entire width of the block (the width being measured from one side surface to the other). The upper surface  502  can be formed with one or more recessed portions or pockets  514  (two in the illustrated embodiment) spaced apart from each other in the direction of the width of the block. 
     As further shown in  FIG. 24 , the block  500  can include vertical reinforcement members  520 ,  522 , which can have the same construction and function as the vertical reinforcement members  420 ,  422  of block  400  described above. The upper end portions of the reinforcement members  520 ,  522  extend into recesses  514  and are adapted to receive a block-connecting element  440  for connecting vertical adjacent blocks, as described in detail above. The block  500  can also be formed with one or more cores, such as a central core  524  positioned between the pairs of reinforcement members and two side cores  526 . The cores  524 ,  526  can extend the entire height of the block. 
     The rear surface  508  of the block can be formed with spaced apart female dovetail grooves  516  that extend partially or the entire height of the block. The grooves  516  can be used to mount a coupling mechanism for coupling one or more soil reinforcing straps to the block. In the embodiment of  FIGS. 24-25 , the coupling mechanism comprises a support bar  600  mounted on the rear surface  508  of the block. The support bar  600  can in turn be used to support reinforcing straps that extend rearwardly into the soil behind the block, as further described below. The support bar  600  can have male dovetail elements  602  mounted at its opposite ends. The male dovetail elements  602  are sized and shaped to be received in the female grooves  516 . 
     During construction of a wall, the support bar  600  can be positioned at a desired location along the height of the block by inserting the dovetail elements  602  in the grooves  516  and resting the dovetail elements  602  on soil that is backfilled behind the block to the desired height of the dovetail elements. The course formed from multiple blocks  500  can be reinforced in the horizontal direction by wrapping one or more soil reinforcing straps  610  around the support bar  600  and extending the straps  610  over the soil behind the wall. Additional soil is then backfilled over the straps  610  to hold them in place. 
     As best shown in  FIG. 25 , each strap  610  extends around the support bar  600  and has an upper layer  612  and a lower layer  614  that extend rearwardly into the soil behind the wall. The rear ends (not shown) of the layers  612 ,  614  can extend the same or different distances into the soil. Also, the layers  612 ,  614  can be arranged to extend at a 90-degree angle relative to the rear surface  508  of the block (like the strap  610  on the left in  FIG. 24 ). Alternatively, the upper and lower layers  612 ,  614  can be arranged to extend in different directions as they extend away from the rear surface  508  of the block. For example, the strap  610  on the right in  FIG. 24  has upper and lower layers  612 ,  614  extending in diverging directions as they extend away from the rear surface  508  of the block at about 45-degree angles relative to the rear surface  508 . 
     The soil reinforcing straps  610  can be conventional soil reinforcing straps and can be made of any of various suitable materials, such as natural or synthetic elastomers (e.g., rubber), metal (e.g., thin sheets or straps of aluminum or galvanized steel) and/or polymeric materials (e.g., synthetic fabric material or sheets of polymeric material). The support bar  600  and dovetail elements  602  can be made of metal (e.g., galvanized steel), polymeric materials, concrete, and/or composite materials. 
     In an alternative embodiment, the support bar  600  need not be used and one or more soil reinforcing straps  610  can be secured to the block by inserting the straps  610  through one or more of the cores  524 ,  526  of the block. 
       FIG. 26  shows an alternative use of the block  500 . In the embodiment of  FIG. 26 , each soil reinforcing strap  610  extends around a separate support ring  700 . Each support ring  700  includes an end portion  702  (which comprises a dovetail element in  FIG. 26 ) that is received within a groove  516  in the rear surface  508  of the block. As shown in  FIG. 27 , a soil reinforcing strap  610  can be arranged to extend through the ring  700  and can have upper and lower layers  612 ,  614  that extend rearwardly into the soil behind the wall a desired distance. In another implementation, as shown in  FIG. 28 , a soil reinforcing strap  610  can have a layer  616  that forms a loop  618  at its forward end that extends through the ring  700  and is folded back and secured to itself, such as with an adhesive, stitching, welding, mechanical fasteners, depending on the material used to fabricate the strap. 
     In alternative embodiments, a coupling mechanism for a soil reinforcing strap can be permanently secured to a block, such as block  500 . For example, the support bar  600  or support ring(s)  700  can be permanently mounted to the block  500  during the molding process. In this embodiment, it would not be necessary to form the grooves  516 . Instead, the end portions  602  of the bar  600  (which do not need to have a dovetail shape in this case) can be partially embedded in the concrete block to permanently secure the bar in place. Similarly, the end portion  702  of the ring  700  (which does not need to have a dovetail shape in this case) can be partially embedded in the concrete block to permanently secure the bar in place. 
     In alternative embodiments, blocks  500  can be used in combination with trunk blocks  14  and anchor blocks  16  to form larger block assemblies, which in turn are used to form the courses of a wall. In such embodiments, support devices for soil reinforcing straps  610 , such as a support bar  600  or support rings  700 , can be mounted to the grooves  22  of the anchor blocks  16  when soil reinforcing straps are needed to reinforce a course of block assemblies. 
       FIGS. 29-32  show various views of a face block  800 , according to another embodiment, which can be either a wet-cast or a dry-cast face block. The block  800  in the illustrated embodiment comprises a face portion  802  and two leg portions  804  formed integrally with and extending rearwardly from the face portion  802 . The face portion  802  in the illustrated embodiment includes a front surface  820 , two side surfaces  822 , a rear surface  824 , a top surface  828 , and a bottom surface  830 . The face portion  802  has a width W 4  extending between the two side surfaces  822 , a depth D 5  extending between the front surface  820  and the rear surface  824 , and a height H 4  extending between the top surface  828  and the bottom surface  830 . Also in the illustrated embodiment, beveled corners  826  link the front surface  820  to each of the side surfaces  822 . 
     As shown, the face portion  802  can also include two protrusions  832  extending rearwardly from the rear surface  824  of the face portion  802 . The protrusions  832  in the illustrated embodiment extend rearwardly from the quarter points of the face portion  802  (i.e., at locations along the width of the face portion  802  that are spaced inwardly from the side surfaces  822  a distance equal to about ¼ the width of the face portion  802 ), but in alternative embodiments need not extend from these locations. For example, in some alternative embodiments, the protrusions  832  extend rearwardly from points on the rear surface  824  closer to or farther from the side surfaces  822  than the quarter points of the face portion  802 . Additionally, in some alternative embodiments, the protrusions  832  need not be spaced apart from the side surfaces  822  by the same distance. 
     The top surface  828  of the face portion  802  can be formed with two recesses or pockets  806 , and the bottom surface  830  of the face portion  802  can be formed with two recesses or pockets  808 . In the illustrated embodiment, the pockets  806 ,  808  are aligned with the quarter points of the top surface  828  and the bottom surface  830 , respectively, and thus are also aligned with the protrusions  832 . In alternative embodiments, the pockets  806 ,  808  need not be so aligned. For example, the pockets  806 ,  808  in alternative embodiments can be located closer to or farther from the side surfaces  822  than the quarter points of the face portion  802 . Further, the pockets  806 ,  808  need not be aligned with the protrusions  832 , and need not be spaced apart from the side surfaces  822  by the same distance. As described in further detail below, aligning the pockets  806  with the pockets  808  vertically (i.e., so that at least a portion of the pockets  806  overlay at least a portion of the pockets  808  when the face portion  802  is viewed from a top plan view) facilitates stacking of multiple blocks  800  in a plurality of courses of blocks  800 . The pockets  806 ,  808  can be sized to receive alignment devices (e.g., block connecting elements  100  or alignment plugs  1500 , which are described in greater detail below) for interconnecting (when stacking) multiple blocks  800  in adjacent courses of blocks  800 , in a manner similar to that described above with regard to courses of block assemblies  10 . 
     Each leg portion  804  can include a front end portion  834  formed integrally with and extending rearwardly from a respective protrusion  832 , and a rear end portion  810  formed integrally with and extending rearwardly from the front end portion  834 . The front end portion  834  can have a height which is less than the height H 4  of the face portion  802 . Each protrusion  832  and respective front end portion  834  can together have an overall generally tapered shape having a width which decreases linearly from a maximum width at the rear surface  824  of the face portion  802  to a minimum width where the front end portion  834  is joined to its respective rear end portion  810 . Thus, the front end portion  834  of each leg portion  804  can couple each rear end portion  810  to a respective protrusion  832  while separating the rear end portion  810  from the respective protrusion  832  by a desired distance. 
     Each rear end portion  810  can include a pair of ridges  838  having a slot  812  between them. The slot  812  can be configured to receive a connecting member that couples the block  800  to another block placed at the rear of the leg portions, as further described below. For example, as shown in  FIGS. 29-32 , each rear end portion  810  can have an upper surface  836  from which the two ridges  838  extend. In the illustrated embodiment, the upper surface  836  is formed so as to be flush with a top surface of the front end portion  834  and the ridges  838  are formed so that they do not extend above the top surface  828  of the face portion  802 . The ridges  838  can be formed in any of various suitable configurations, such that the slot  812  is defined between them. As best shown in  FIG. 30 , each ridge can comprise a truncated pyramid  840  which tapers from a relatively large rectangular base at the upper surface  836  to a relatively small top surface  844 . Each ridge  838  can also comprise a gambrel portion  842  which extends outward from the rearmost portion of the truncated pyramid  840  toward the other ridge  838  of the rear end portion  810 . In this configuration, a tapered slot  812  is defined between the two ridges  838  and in particular between the two gambrel portions  842  of the rear end portion  810 . Additionally, a pocket  846  is created between the truncated pyramids  840  forward of the gambrel portions  842 , which can be occupied by an end portion (e.g., a flange) of a connecting member, as further described below. 
     The block  800  can be formed with any of various desired textures and/or configurations that enhance the appearance of the block  800 , for example on the front surface  820  of the face portion  802 . For example, the front surface  820  can be provided with any of the textures, patterns, designs, or configurations described above with regard to face block  12 . As shown in  FIG. 30 , a lifting ring  814  can be cast into the rear surface  824  of the face portion  802  to facilitate lifting and placement of the block  800 , such as with a backhoe or other suitable equipment. 
     In particular embodiments, the block  800  is a wet-cast block has a weight of less than 1,500 lbs., more desirably less 1,000 lbs., and even more desirably less than 800 lbs.; a front face area of at least 4.0 sq. feet, and more desirably at least sq. 5.0 feet, and even more desirably at least sq. 5.33 feet; and a face area ratio of less than 2.0 feet, more desirably less 1.5 feet, and even more desirably less than 1.0 foot. The “face area ratio” of a block is defined as the ratio of the volume of concrete needed to form the block divided by the face area of the block. 
     In one specific implementation, the block  800  can have an overall width W 4  of about 48 inches, an overall depth D 4  of about 24 inches, and an overall height H 4  of about 16 inches. The face portion  802  can have a depth D 5  of about 6 inches, the protrusions can have a depth of about 2 inches, the leg portions  804  can have a depth of about 16 inches, the rear end portions  810  can have a width W 5  of about 8 inches, the top surface  844  of the truncated pyramid  840  can have a width W 6  of about 2 inches and a depth D 7  of about 3.5 inches, and the gambrel portion  842  can have a depth D 6  of about 3 inches. In such an implementation, the block  800  is a wet-cast block having a weight of about 746 lbs., a front face area of 5.33 sq. feet (48 inches×16 inches), a volume of about 5.15 cubic feet, and a face area ratio of about 0.966. 
     Multiple blocks  800  of this size can be used to form a wall up to about 5 feet in height without additional earth retention mechanisms (such as geogrid) and without additional blocks that extend the depth of each course. The depth of the void  816  defined between the two leg portions  804  in the illustrated embodiment is about 18 inches. During construction of a wall, the voids  816  of each block in a course and each void between adjacent blocks  800  can be backfilled with gravel. Most building codes require at least 12 inches of gravel behind each course of a wall for sufficient drainage. Thus, backfilling the voids  816  and the voids between adjacent blocks with gravel can satisfy the backfill requirement without additional gravel placed behind the rear of the blocks (i.e., behind the leg portions  804 ). 
       FIGS. 33-36  show various views of a trunk block  900  that can be used in combination with the block  800  in various configurations to increase the strength or other desirable characteristics of a course of blocks. The trunk block  900  can be either a wet-cast or a dry-cast trunk block. The trunk block  900  can have opposite end portions  902  and an intermediate portion  908  which interconnects the two end portions  902 . The intermediate portion  908  can have a depth which is less than a depth of the end portions  902 , a height which approximates the height H 4  of the face block  800 , and a length which serves to separate the end portions  902  by about the same distance as that which separates the rear end portions  810  of the leg portions  804  of the block  800 . 
     Each of the end portions  902  can be formed with one or more slots  904   a ,  904   b ,  904   c  (three in the illustrated embodiment) in the upper surface of the end portion  902  and can have a recess or pocket  906  formed between and which interconnects the slots  904   a ,  904   b ,  904   c  in the upper surface of the end portion  902 . Each end portion  902  can comprise a wall  912  formed integrally with the intermediate portion  908  and two upwardly extending protrusions  910   a ,  910   b , between which is formed the slot  904   c . The protrusions  910   a ,  910   b  can be positioned such that slot  904   a  is defined between wall  912  and protrusion  910   a  and such that slot  904   b  is defined between wall  912  and protrusion  910   b . As shown, the protrusions  910   a ,  910   b  and the wall  912  can each include two gambrel-shaped portions resembling the gambrel portions  842  of block  800 , such that each of the slots  904   a ,  904   b ,  904   c  have a width which tapers from a maximum width at the top of the block  900  to a minimum width at the bottom of the slot. 
     In one specific implementation, the block  900  can have an overall width W 8  of about 32 inches, an overall depth D 8  of about 8 inches, and an overall height H 8  of about 16 inches. Each end portion  902  can have a width W 9  of about 8 inches and a depth D 8  of about 8 inches, and the intermediate portion  908  can have a depth D 9  of about 6 inches. In such a configuration, the block  900  is a wet-cast block and can have a weight of about 286 lbs. 
       FIGS. 37-40  show various views of a block assembly formed with one block  800  and a block  900  placed in a perpendicular relationship with respect to the leg portions  804  of the block  800 . As shown, the block  900  can be positioned such that the end portions  902  of the block  900  are placed against the rear end portions  810  of the block  800  and the slots  904   b  are aligned with slots  812  of the end portions  810 . Connection devices (described below) can be placed in respective pairs of slots  812 ,  904   b  to interconnect the blocks  800 ,  900 . The block  900  can serve as an anchor block and can extend the effective depth of the block  800  to permit construction of taller walls. The block assembly defines an enclosed space in a horizontal plane extending through the blocks  800 ,  900 . In other words, the space defined by the blocks  800 ,  900  in the illustrated embodiment is enclosed on all sides expect at the top and bottom of the blocks. When forming courses of a wall from multiple block assemblies, backfill material, such as gravel, can be placed in the enclosed space. 
     In one specific implementation, the block assembly shown in  FIGS. 37-40  can have an overall width of about 48 inches, an overall depth of about 32 inches, and an overall height of about 16 inches. The ridges  838  and protrusions  910 , and thus the slots  812 ,  904   a ,  904   b , and  904   c  can have a height H 9  of about 4 inches. In the embodiment illustrated in  FIGS. 37-40 , the block  800  is formed integrally with protrusions or nubs  848  for interconnecting the block  800  with another block in an adjacent course of blocks, as illustrated in  FIGS. 41-43 . Multiple block assemblies of this size can be used to form a wall up to about 7 feet in height without additional earth retention mechanisms (such as geogrid). 
       FIGS. 41-43  show various views of two partial courses of a curvilinear wall constructed from multiple block assemblies of the type shown in  FIG. 37 . The block assemblies of the upper course can be placed in a running bond pattern with respect to the block assemblies of the lower course. In this manner, the front portion  802  of each block  800  in the upper course can straddle the front portions  802  of two adjacent blocks  800  in the lower course. By virtue of the leg portions  804  being at the quarter points of the block, each leg portion  804  in the upper course can be vertically stacked on top of a leg portion  804  in the lower course. 
       FIGS. 44-47  show various views of a block assembly comprising one block  800  and two blocks  900 , wherein each of the blocks  900  is placed end-to-end with a leg portion  804  of the block  800  to extend the effective depth of the block  800 . The blocks  900  can be aligned with the leg portions  904  such that a slot  904   c  of each block  900  is aligned with a respective slot  812  of a leg portion  804 . Connection devices (described below) can be placed in respective pairs of slots  812 ,  904   c  to interconnect the blocks. In the embodiment illustrated in  FIGS. 44-47 , the block  800  is formed integrally with protrusions or nubs  848  for interconnecting the block  800  with another block in an adjacent course of blocks. 
     In one specific implementation, the block assembly shown in  FIGS. 44-47  can have an overall width of about 48 inches, an overall depth of about 56 inches, and an overall height of about 16 inches. Multiple block assemblies of this size can be used to form a wall up to about 12 feet in height without additional earth retention mechanisms (such as geogrid). In some applications, a 12-foot high wall can comprise three lower courses formed from multiple block assemblies of the type shown in  FIGS. 44-47 , two or more intermediate courses formed from multiple block assemblies of the type shown in  FIGS. 37-40 , and two or more courses formed from multiple blocks  800 . 
     Integral protrusions  848 , block-connecting elements  100  ( FIGS. 11-16 ), or block connecting elements  1500  ( FIGS. 57-60 ) can be used to interconnect blocks  800  in adjacent courses that are stacked vertically, with a positive batter, or with a negative batter, as described in connection with the block shown in  FIG. 2 . For example, when laying a new course on a previously laid course, the lower portion  1502  of a block-connecting element  1500  is placed within a pocket  806  in a block in the previously laid course and the upper portion  1504  is inserted into the pocket  808  of a block of the newly formed course. 
       FIGS. 48-51  show various embodiments of connecting elements that can be used to interconnect one end portion  902  of a block  900  to a rear end portion  810  of a leg portion  804  of a block  800 .  FIG. 48  shows a connecting element in the form of a bolt or screw  1000  placed in a slot  812  of a rear end portion  810  of a leg portion  804  and a slot  904   b  of a block  900 . A head portion  1002  of the bolt  1000  can be placed in the pocket  906  of the block  900  and a nut  1004  screwed onto the bolt  1000  can be placed in a pocket  818  of the rear end portion  810  so as to restrict separation of the blocks  800 ,  900  front to back (in the direction of the depth of the block assembly). In an alternative embodiment, the head portion  1002  can be positioned in the pocket  818  and the nut  1004  can be positioned in the pocket  906 . In another alternative embodiment, the connecting element can be a threaded piece of rebar that has a nut threaded onto each end of the piece of rebar. In any case, the enlarged end portions of the connecting element are positioned to bear against adjacent surface portions of the pockets  818 ,  906  to resist separation of the blocks. 
       FIG. 49  shows a connecting element in the form of an I-shaped section of material  1010  having opposite end portions, or flanges,  1012  disposed in pockets  818 ,  906  and a web  1014  disposed within slots  812 ,  904   b . Any of various suitable materials can be used to form the I-shaped section of material  1010 , for example, any of various commercially available structural steel I-beams.  FIG. 50  shows a connecting element in the form of a C-shaped section of material  1020  having opposite end portions, or flanges,  1022  disposed in pockets  818 ,  906  and a web  1024  disposed within slots  812 ,  904   b . Any of various suitable materials can be used to form the C-shaped section of material  1020 , for example, any of various commercially available structural steel channel sections.  FIG. 51  shows a connecting element in the form of an S-shaped section of material  1030  having opposite end portions, or flanges,  1032  disposed in pockets  818 ,  906  and a web  1034  disposed within slots  812 ,  904   b . The connecting elements  1010 ,  1020 ,  1030  can be made from any of various suitable materials, such as metals (e.g., stainless or galvanized steel, aluminum), polymers or composite materials, such as carbon-fiber- or fiberglass-reinforced steel. Although not illustrated, any of the connecting elements  1000 ,  1010 ,  1020 ,  1030  can be used in the same manner to interconnect a slot  904   c  of a block  900  with a slot  812  of a rear end portion  810  of a block  800  where a block  900  is placed end-to-end with a leg portion  804  of a block  800  as shown in  FIG. 45 . 
       FIG. 52  is a top plan view of a course of a wall comprising blocks  1100  and corner blocks  1200 . Blocks  1100  and the corner blocks  1200  can be either wet-cast or dry-cast blocks. The blocks  1100  have an overall configuration, size and weight similar to that of blocks  800  ( FIGS. 29-32 ). A block  1100  can include a face portion  1106  having a pair of pockets  1102  formed in its upper surface and a corresponding pair of pockets (not shown) formed in its lower surface. The pockets formed in the upper and lower surfaces of the face portion  1106  can be configured to receive a block connecting element  100  ( FIG. 11-16 ) or  1500  ( FIGS. 57-60 ) for interconnecting multiple blocks  1100  in adjacent courses that are vertically stacked. The block  1100  can also include a pair of legs  1108  having respective rear end portions  1110  with slots  1104  formed therein. In the illustrated embodiment, the pockets  1102  are situated at the quarter points of the face portion  1106  and the legs  1108  are coupled to the face portion  1106  at the quarter points of the face portion  1106 . In alternative embodiments, however, the pockets  1102  need not be situated at the quarter points of the face portion  1106  and the legs  1108  need not be coupled to the face portion  1106  at its quarter points. 
     In the illustrated embodiment, the face portion  1106  can have a generally rectangular configuration in plan view with two beveled corners  1112 . Each rear end portion  1110  can have a generally rectangular configuration in plan view with two beveled corners  1114 . Each leg  1108  can have a generally hourglass-shaped configuration and can couple a rear end portion  1110  to the face portion  1106  while separating the rear end portion  1110  from the face portion  1106  by a desired distance. 
     The overall configuration and size of corner blocks  1200  is illustrated in  FIG. 52 , where the corner blocks  1200  are illustrated adjacent to the blocks  1100 , which have an overall configuration, size and weight similar to that of blocks  800 . A corner block  1200  in the illustrated embodiment comprises a face portion  1202  which includes two pockets  1212  formed in its upper surface and a corresponding pair of pockets (not shown) formed in its lower surface. The pockets formed in the upper and lower surfaces of the face portion  1202  can be configured to receive a block connecting element  100  ( FIG. 11-16 ) or  1500  ( FIGS. 57-60 ) for interconnecting multiple blocks  1200  in adjacent courses that are vertically stacked. 
     The corner block  1200  can also include a leg portion  1204  which includes a slot  1214  and extends from a quarter point of the face portion  1202 , and a corner piece  1206  at the end of the face portion  1202  farthest from the leg portion  1204 . In the illustrated embodiment, the corner piece  1206  has a side surface  1208  that is perpendicular to the front face  1210  of the block  1200 . Thus, when placed at the intersection of two wall sections, the corner block  1200  can form a 90-degree corner in the wall. In alternative embodiments, the leg portion  1204  need not be coupled to the face portion  1202  at its quarter point, the pockets  1212  can be situated in any of various suitable locations on the surface of the corner block  1200 , and the angle formed between the side surface  1208  and the front face  1210  can be any of various suitable angles. 
       FIG. 53  is a top plan view of a course of a wall comprising blocks  1100 ,  1200 ,  1300 , showing various possible positions of the blocks relative to each other. Blocks  1300  in the illustrated embodiment have an overall configuration, size and weight similar to that of blocks  900  ( FIGS. 33-36 ). The blocks  1300  can be either wet-cast or dry-cast blocks. The blocks  1300  can each have two end portions  1304  having slots  1302  formed therein, and an intermediate portion  1306  which interconnects and separates the two end portions  1304 . The blocks  800  and  900  can be placed in the same positions as blocks  1100  and  1300 , respectively, and can be used with the corner blocks  1200  in the manner shown in  FIG. 53 . As shown, the slots  1104 ,  1214 , and  1302  of the blocks  1100 ,  1200 , and  1300 , respectively, can be configured to receive a connecting element such as connecting element  1000 ,  1010 ,  1020 , or  1030 . 
       FIG. 54  is a top plan view showing multiple blocks  1100  placed back-to-back with the leg portions  1108  nested within each other to form a barrier wall or bench wall. Blocks  800  can be positioned in the same manner to form a barrier wall or bench wall.  FIG. 55  is a top plan view showing multiple blocks  1100  and blocks  1300  being used to interconnect the leg portions  1108  of adjacent blocks  1100 . Blocks  800  and  900  can be positioned in the same manner as blocks  1100  and  1300 , respectively, as shown in  FIG. 55 . 
       FIG. 56  is a top plan view of another embodiment of a block  1400  comprising a face portion  1402 , a rear portion  1406  that extends parallel to the face portion  1402 , and two leg portions  1404  extending from the face portion to the rear portion  1406  and forming an enclosed space  1412  between them. The face portion  1402  and the rear portion  1406  can each include four beveled corners  1410 . The leg portions  1404  in the illustrated embodiment extend rearwardly from the quarter points of the face portion  1402 . A block  1400  in the illustrated embodiment comprises two pockets  1408  formed in the upper surface and at the quarter points of the face portion  1402  and a corresponding pair of pockets (not shown) formed in the lower surface of the face portion  1402 . The pockets formed in the upper and lower surfaces of the face portion  1402  can be configured to receive a block connecting element  100  ( FIG. 11-16 ) or  1500  ( FIGS. 57-60 ) for interconnecting multiple blocks  1400  in adjacent courses that are vertically stacked. In a specific implementation, the block  1400  has an overall width W 11  of about 48 inches, an overall depth D 11  of about 18 inches, and a height of about 16 inches. In alternative embodiments, pockets can be formed in the upper and/or lower surfaces of the rear portion in addition to or instead of the pockets formed in the face portion  1402 . In other alternative embodiments, the leg portions  1404  and the pockets  1408  can be situated at locations other than the quarter points of the face portion  1402  and the rear portion  1406 . 
       FIG. 57  shows a perspective view and  FIG. 58  shows a top plan view of another embodiment of an alignment plug  1500  (also referred to as an alignment device or connection device) that can be used to interconnect multiple blocks  800 , multiple blocks  1100 , multiple blocks  1200 , or multiple blocks  1400 , stacked on top of each other in courses of a wall. The plug  1500  comprises a lower portion  1502  and an upper portion  1504 . The lower portion  1502  is sized to be placed in a pocket  806  in the upper surface of a first block  800  (or a corresponding pocket in any of blocks  1100 ,  1200 , or  1400 ) and the upper portion  1504  is sized to be placed in a pocket  808  in the lower surface of a second block  800  (or a corresponding pocket in any of blocks  1100 ,  1200 , or  1400 ) stacked on top of the first block. In particular embodiments, the plug  1500  can be made of concrete, although other suitable materials, such as polymers, composites, or metals can be used to form the plug  1500 . 
       FIG. 59  shows the placement of a plug  1500  in pockets  806 ,  808  to form a wall having a 4.5-degree setback (a positive batter). As shown, the lower portion  1502  of the plug  1500  is placed in a pocket  806  in the upper surface of a first, lower block  800  such that the upper portion  1504  is in a rearward position. The pocket  808  in the lower surface of a second, upper block  800  is placed over the upper portion  1504 , which positions the second block in a setback relationship relative to the first block. 
       FIG. 60  shows the placement of a plug  1500  in pockets  806 ,  808  to form a vertical wall. As shown, the lower portion  1502  of the plug  1500  is placed in a pocket  806  in the upper surface of a first, lower block  800  such that the upper portion  1504  is in a forward position. The pocket  808  in the lower surface of a second, upper block  800  is placed over the upper portion  1504 , which aligns the second block vertically with respect to the first block. 
     Embodiments of wall blocks described herein can be fabricated in some cases from approximately half the material, while retaining full functionality, as compared to many traditional wall blocks. Except where physically impossible, any of the features of any of the embodiments described herein can be used with any of the other embodiments described herein. Any of the concrete components described herein can be fabricated as wet-cast or dry-cast concrete components. As used herein, the term “integral” or “integrally” means that the components referred to are formed and cured together in the same mold (from wet-cast concrete or dry-cast concrete) rather than formed separately and then attached to one another at a later time. 
     In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.