Patent Publication Number: US-10316485-B1

Title: Retaining wall block

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to blocks used for the construction of retaining walls. More specifically, the invention relates to a cementitious block that is easier to place into a secure block retaining wall than existing blocks while also being able to be offer alternative methods for increasing the retaining strength of the wall made from the blocks. 
     2. Description of Related Art 
     Retaining walls made from dry stacked concrete blocks have become widely accepted for both landscaping and construction projects. These concrete blocks are mass produced, which makes them relatively inexpensive, and are available in several colors and textures. These blocks offer the durability of concrete with the attractiveness of various architectural features. Due to their significant weight, when the blocks are assembled to form a wall, they have the ability to retain soil and earth while aesthetically defining walkways, property lines, and other landscaping features. It is possible to build a wall from such blocks quickly and without the need for special skilled labor, and how quickly the wall is constructed depends on the size of the blocks used and ease of stacking the blocks for the workers. 
     To increase the structural integrity of the wall made from these blocks, various methods have been introduced to provide features on the blocks to interlock them together. Furthermore, walls formed from blocks that have been interlocked look more professional as the blocks are uniformly and consistently arranged. One example of an interlocking feature is a lip or protrusion extending along the lower rear edge of each block. As each successive course is laid over an underlying course, the lips of the blocks in the new course are fitted over the rear upper edge of the underlying course of blocks, which interlocks the blocks and also sets the new course back from the lower course it is resting on a predetermined distance. Another interlocking method is the use of pins extending vertically between courses of blocks to resist lateral shifting or movement between adjacent blocks and courses. Similar to the lip discussed above, pins also provide a registry function, by assuring that the front faces of the blocks are vertically aligned or setback a predetermined distance. 
     As the use of these concrete retaining wall blocks becomes prevalent in commercial and large-scale projects, additional soil-reinforcing materials and methods are needed to ensure that the retaining wall can prevent lateral displacement of the soil and toppling of the wall. One material that is used is a geogrid, which are commonly used to reinforce retaining walls by preventing the soils from moving by transferring the forces to a larger area of soil other than just the soil in contact with the wall. Alternatively, soil anchors or metal ribbed or wave-shaped strips can be attached to the wall and then buried in the backfilled area to provide additional strength to the retaining wall. Additionally, several of these larger commercial projects have specifications requiring engineered backfill rather than just retaining the native soil to ensure the wall maintains its integrity. 
     It is therefore desirable to have relatively lightweight block that allows easier and quicker installation while allowing the use of various soil-reinforcing methods and materials with increased room for more engineered backfill in contact with the individual blocks of the wall. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a retaining wall block that includes a number of features making it easier to place the block into a secure block retaining wall than existing blocks while also being able to be offer alternative methods for increasing the retaining strength of the wall made from the blocks. The invention provides for a wall block generally comprising a block body having a front face with a plurality of support legs extending rearward therefrom, opposed first and second side surfaces, and opposed and substantially parallel upper and lower surfaces. The rearward extending legs of the block increase the depth of the lower surface, which provides a more stable base for the block, while also providing a reduced weight compared to a rectangle block having the same depth. Significantly lowering the weight of the concrete blocks by removing large portions of the blocks behind the front face make for much easier handling by the installer. It also saves cementitious material without compromising the strength and structural integrity of the block. 
     Additionally, the use of the legs to provide a stable base rather than a fully rectangular block allows more space for engineered backfill to be added to the area between the legs and behind the wall to increase drainage and stability of the retained area. In the preferred embodiment, the contour of the legs provide additional soil retaining capabilities and serve as hand holds to ease in installation. Specifically, the legs taper as they extend away from the block but terminate in a larger than the narrowed taper diameter cylinder shape. This larger termination-point shape of the legs allows the engineered backfill or soil to be compacted between the legs while also providing an anchor to help to increase the retaining strength of the blocks. 
     Preferably, the blocks of the present invention have three rearward extending support legs. The two side legs are not adjacent to either of the side edges of the block and are spaced an equidistance apart from the center leg. The center leg does not extend rearward from the middle of the block, but is rather offset from the middle to allow for increased manufacturing efficiency. Because the side legs are spaced equidistance apart from the center leg, which is offset, the side legs are also offset the same amount (i.e., the distance from one side leg to the side of the block nearest it is greater than the distance from the other side leg to the side of the block nearest it. The distance between the center points of the two side legs is the same as the total distance from the center point of both side legs and the respective edge of the block nearest each. This preferred leg spacing of the side legs allows the side legs of each successive course of blocks to rest on the side legs of the prior-laid rows, while allowing the center legs to float freely (i.e., not resting on the course below) as will be discussed fully below. The free-floating center leg allows for attachment of additional stabilization means to the bottom of the center leg without preventing the blocks from resting directly on the course below. The third center leg also balances the weight of the block such that the block is not front heavy, and the use of the two side legs makes the block better balanced from side-to-side than other prior art blocks. Because the weight of the block is better balanced, the block is easier to move and install and less likely to be dropped or broken during installation. 
     The blocks also employ a retaining pin system adapted to align and secure the blocks together. At least one retaining pin extends vertically from a bore on the upper surface of each block. Instead of relying upon a singular bore or a relatively small cavity into which the pin is to be located, longitudinal channels are provided in the bottom face of the blocks. This enables an upper block to be slid into a proper position over a lower block, where the pin in the lower block merely enters the channel in the upper block, rather than having to be located with a discrete bore or cavity. Additionally, two or more retaining pins may also be employed, for additional interlocking strength, with each pin easily being accommodated within a channel of the overlying blocks. In one embodiment, the bores and channels in the blocks are axially coincident with the center line of the block, and located an identical distance from the rear face of each block. This arrangement effects a co-planar alignment for the front faces of the blocks (i.e., the blocks form a vertical wall when interlocked). Alternatively, the upper pin bore holes may be located closer to the rear face of each block than the longitudinal channel, effecting a setback for the front face of each successively higher course of blocks. 
     An alternative, novel retaining pin system is provided for as well. In this embodiment, the retaining pin has a head portion and then shoulders down to a smaller diameter body section. The pin is placed in a bore that extends through the entire height of the block and shoulder of the pin rests on the shoulder of the bore to prevent the pin from falling through the bore. The head of the pin is sized so as to not protrude through the top of the block when resting on the shoulder of the bore. The body of the pin is long enough so that when resting in the block, the pin extends vertically downward from the bottom surface of the block. The downward extending portion of the pin rests behind and adjacent to the rear surface of the block in the course below, which prevents the upper block from moving forward with respect to the lower block and creates a setback for the front face of the upper block. Instead of relying upon a singular bore or a channels in the bottom face of the upper blocks that have to be aligned, this retaining pin system allows the blocks to be slid into a greater ranges of position, limited only by the distance between the rearward extending legs of the lower block. This system also allows easier installation as the upper block can be set upon the lower block and the retaining pins can be placed in the bores. Because the bottom of the upper block is resting on the top of the lower block, the pins will not be able to seat completely and extend from the bottom until the upper block is slid back into place. Once the bottom of the bore hole passes behind the top of the lower block, the pins will fall the remaining distance into place and lock the block in place. 
     A parapet wall block is also provided for that can be used in conjunction with the retaining wall block of the present invention to create a parapet wall. The parapet wall block generally comprises a block body having a front face, a rear face with a plurality of recesses shaped and spaced to accept the rearwardly extending support legs of the retaining wall block, opposed first and second side surfaces, and opposed and substantially parallel upper and lower surfaces. The parapet wall block has less depth than the retaining wall block, and when used in conjunction with the retaining wall blocks allows the construction of a narrower freestanding wall or fence. The preferred embodiment of the parapet wall block has a pin-receiving channel located on the upper surface to receive and engage the retaining pins used to anchor the retaining wall blocks. To construct a parapet wall, a retaining wall block is placed on a level surface, and then a parapet wall block is placed with its rearward side engaging the legs extending the rearward side of the retaining wall block. For the next course above, the parapet wall block is placed on the retaining wall block of the first course, and the retaining wall block of the second course is placed on the parapet wall block of the first course. This altering layout is used to create additional stability when coupled with the retaining pin system. 
     For the purposes of this application “upper” and “lower” refer to the placement of the block in a retaining wall, wherein the lower surface faces down towards the ground. To create a retaining wall, a row of blocks is placed in a first course. Subsequently, a second course is laid on top of this by positioning the lower surface of one block on the upper surface of the blocks in the first course. This process continues until the desired height of the retaining wall is achieved. The blocks of this invention are preferably made from concrete, but other suitable materials may be used. The front face of the blocks may be smooth or may have a roughened appearance to appear more like natural stone as the blocks are formed in a mold and various textures can be formed on the surface, which is known in the art. 
     The novel features and construction of the present invention, as well as additional objects thereof, will be understood more fully from the following description when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The improved process of the invention is further described and explained in relation to the following figures of the drawings wherein: 
         FIG. 1  is a perspective view of the upper surface of the retaining wall block of the present invention. 
         FIG. 2  is a perspective view of the lower surface with leveling pads of the retaining wall block of the present invention. 
         FIG. 3  is a top view of a retaining wall created with the retaining wall blocks of the present invention. 
         FIG. 4  is a perspective view of the front side of a retaining wall created with the retaining wall blocks of the present invention. 
         FIG. 5  is a perspective view of the of rear side of a retaining wall created with the retaining wall blocks of the present invention. 
         FIG. 6  is a perspective view of the rear side of the retaining wall block of the present invention for use with an alternate retaining pin system. 
         FIG. 7A  is a side view of the retaining wall block of the present invention for use with an alternate retaining pin system. 
         FIG. 7B  is a side view of the retaining wall block of the present invention for use with an alternate retaining pin system. 
         FIG. 8  is a top view of the retaining wall block of the present invention for use with an alternate retaining pin system. 
         FIG. 9  is a perspective view of the rear side of a parapet wall block for use in conjunction with the wall block of the present invention. 
         FIG. 10  is a top view of a parapet wall created with the parapet wall block of  FIG. 9  and the retaining wall block of the present invention. 
         FIG. 11  is a perspective view of a parapet wall created with the parapet wall block of  FIG. 9  and the retaining wall block of the present invention. 
         FIG. 12  is a side view of a parapet wall created with the parapet wall block of  FIG. 9  and the retaining wall block of the present invention. 
         FIG. 13  is a top view of the manufacturing mold layout of the retaining wall block of the present invention. 
     
    
    
     Like reference numerals are used to describe like parts in all figures of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , retaining wall block  10  of the present invention is shown. Retaining wall block  10  comprises a block body having front face  12  with a plurality of support legs  20 ,  22  extending rearward therefrom, opposed first and second side surfaces  14  (only one side surface shown), and opposed and substantially parallel upper surface  16  and lower surface  18 . Preferably first and second side surfaces  14  are tapered inward as they extend rearward from front face  12 , which decreases the material needed to make block  10  and reduces the weight of block  10 . When one block  10  is placed adjacent to another block  10  in the forming of a retaining wall, the edge of front face  12  and side surface  14  of one block  10  will be in contact with the edge of front face  12  and side surface  14  of the adjacent block  10 , which creates a continuous rock appearance across the front of the retaining wall in both straight walls and concave walls. Due to the tapering side surfaces  14 , convex walls can be built as well as the blocks  10  can be angled backwards up to the angle that the tapered side surfaces  14  of adjacent blocks  10  touch. 
     Rearward extending legs  20 ,  22  of retaining wall block  10  provide a stable base for block  10  by increasing the overall footprint depth of block  10 . The use of rearward extending legs  20 ,  22  rather than a solid rectangular block provides a significant savings in the weight of the block and the materials necessary to form the block while still providing a significant footprint depth to increase the stability of block  10 . Significantly lowering the weight of block  10  by the use of legs  20 ,  22  and foregoing a solid block makes block  10  much easier to handle and install. It also saves cementitious material without compromising the strength and structural integrity of block  10 . Furthermore, the use of rearward extending legs  20 ,  22  to provide a stable base allows more space for engineered backfill to be added to the area between legs  20 ,  22  and behind the wall to increase drainage and stability of the retained area. Preferably, rearward extending legs  20 ,  22  are contoured and taper as they extend rearward from block  10  before terminating in a cylindrical shape. As shown in  FIG. 1 , the diameter of the cylindrical shape termination of legs  20 ,  22  is larger than the width of tapered legs  20 ,  22  at the point where the cylindrical shape termination begins. This shape of legs  20 ,  22  provides additional soil retaining capabilities by allowing the engineered backfill or soil to be compacted between and around legs  20 ,  22 , while also providing an anchor to help to increase the retaining strength of block  10 . The cylindrical termination of legs  20 ,  22  also provides a hand hold to aid the workers when moving and installing block  10 . 
     In the preferred embodiment, block  10  of the present invention has three rearward extending support legs: center leg  20  and two side legs  22 . Center leg  20  extends rearward from block  10 , but not directly from the middle of block  10  as it is offset to allow for increased manufacturing efficiency, as will be discussed below and shown in  FIG. 13 . Side legs  22  are symmetrically spaced apart from center leg  20  and the distance between the center points of side legs  22  is defined as “c” as shown in  FIG. 1 . Because side legs  22  are equidistant from center leg  20 , which does not extend rearwardly from the middle of block  10 , the distance between left side leg  22  and left side surface  14  of block  10  is not the same as the distance between right side leg  22  and right side surface  14  of block  10 . The distance between left side leg  22  and left side surface  14  is defined as “a” as shown in  FIG. 1 , and the distance between right side leg  22  and right side surface  14  is defined as “b” also as shown in  FIG. 1 . The distance between the center points of side legs  22  (or “c”) is the same as the sum of the distances from the center point of both side legs  22  and the respective edges  14  nearest each (or “a” and “b”). In other words, “a”+“b”=“c.” This preferred leg spacing of side legs  22  allows side legs  22  of each successive course of blocks to rest on side legs  22  of the prior-laid rows, while allowing center leg  20  to float freely (i.e., not resting on the course below) as will be discussed fully below in reference to  FIG. 4 . Importantly, neither of side legs  22  are located adjacent to either of side surfaces  14  of block  10 . Pin apertures  30  are cylindrical bores that extend through the entirety of block  10  from upper surface  16  to lower surface  18  (as shown in  FIG. 2 ). 
     Referring to  FIG. 2 , the preferred embodiment of retaining wall block  10  of the present invention is shown in a position with lower surface  18  displayed. Block  10  in  FIG. 2  has been is flipped upside down from the view shown in  FIG. 1 . Located on lower surface  18  of block  10  is are three leveling pads—large leveling pad  24  located congruent with and along one side leg  22 , small leveling pad  26  is located at the termination point of opposite side leg  22 , and small leveling pad  27  located on lower surface  18  in line with same side leg  22  that small leveling pad  26  is located on. Leveling pads  24 ,  26  and  27  are used in conjunction with each other to create a three point leveling system for block  10 . Leveling pads  24 ,  26  and  27  are thin plateaus that extend from the surface of lower surface  18  and/or legs  22 . Because leveling pads  24 ,  26  and  27  extend slightly from the surface of block  10 , they serve as the load-bearing points for the entire block, and the entire weight of block  10  is dispersed only on the surface area of leveling pads  24 ,  26  and  27  rather than across the entire surface area of lower surface  18  and lower surface of legs  20 ,  22 . 
     Leveling pads  24 ,  26  and  27  help prevent the rocking of block  10  when placed in a retaining wall on top of other courses of blocks due to any manufacturing imperfections, such as a block that is bowed or twisted. Blocks without leveling pads that are bowed or banana-shaped from side surface to side surface have a tendency to break vertically through the face of the block when placed in a wall due to the vertical forces all being concentrated in the one point at the apex of the curve. The use of leveling pads  24 ,  26  and  27  accounts for and corrects any slight bowing that would be present due to their extension from the surface and spreads the weight of block  10  out over leveling pads  24 ,  26  and  27  rather than it being concentrated in the one bowed point. Similarly, blocks that have a slight twist (i.e., where two of the four corners of the block would be floating when placed on a flat surface) tend to break diagonally through the face due to a torsion load as the weight of the blocks above put undue pressure on the floating corners. The use of leveling pads  24 ,  26  and  27  accounts for and corrects and slight twisting that would be present due to their extension form the surface and by spreading the weight of the block  10  out over leveling pads  24 ,  26  and  27 . Additionally, blocks with leveling pads are capable of holding geogrid materials in place better than blocks without leveling pads due to the entire weight of the block being located in the three load-bearing points rather than dispersed across the entire bottom surface area. 
     Referring to  FIG. 3 , a top view of a 2-course stack of blocks is shown revealing the alignment of leveling pads  24 ,  26  and  27  of one block in relation to other blocks. When the second course of blocks is stacked in brick formation (i.e., set where the center of the front face of the top block is aligned with the adjacent edges of the two lower blocks from the prior course), outside legs  22  align over outside legs  22  of the prior course of blocks. Because leveling pads  24 ,  26  and  27  are the load-bearing points of each block and overlap the leveling pads on the blocks below creating a vertical alignment, the full weight of each block to be transferred down and through the load-bearing points of the blocks below it. For example, for the top block in  FIG. 3 , left larger leveling pad  24  overlaps smaller leveling pads  26  and  27  of the block in the lower course of blocks. As all the weight is borne by leveling pads  24 ,  26  and  27 , this ensures that the free-floating center leg (as will be discussed below) bears no weight. 
     Referring back to  FIG. 2 , pin apertures  30  and pin-receiving channels  28  are shown in lower surface  18  of block  10 . Pin apertures  30  are cylindrical bores that extend through the entirety of block  10  from upper surface  16  (as shown in  FIG. 1 ) to lower surface  18 . Pin-receiving channels  28  are shallow, longitudinal channels that run horizontally across lower surface of block  10 . In one embodiment, pins extend vertically from pin aperture  30  on upper surface  16  of block  10  and enters pin-channel  28  in an additional block that is placed in the course above. The use of pin-receiving channel  28  rather than a discrete bore or cavity enables an upper block to be slid into a proper position over a lower block and allows more side-to-side freedom in block placement. 
     In this embodiment, there are two pin apertures  30  and two pin-receiving channels  28  per block, and pin apertures  30  are located further away from face  12  of block  10  than pin-receiving channels  28 , which effects a setback for the front face of each successively higher course of blocks equivalent to the offset distance between pin-receiving channels  28  and pin apertures  30 . In an alternate embodiment of this pinning system, pin-receiving channels  28  and pin apertures  30  are not offset and are axially coincident with the center line of block  10 , which creates co-planar alignment for the front faces of the blocks (i.e., the blocks form a vertical wall) when interlocked. 
     Referring to  FIG. 4 , a partial example of a two course retaining wall is shown after having the blocks interlocked with pins  32 . In this embodiment, pins  32  have a larger diameter head portion that is shouldered-down to a narrower diameter body portion. Both the head portion and body portion of pins  32  are cylindrical in shape. Pin apertures  30  are large enough to accommodate the narrower diameter section of the body portion of pins  32 , but not large enough to accommodate the larger diameter section of the head portion of pins  32 . When pin  32  is inserted in pin aperture  30 , the entire narrower diameter body portion of pin  32  is in pin aperture  30 , and the shoulder of the pin between the head and body portion rests against upper surface  16  of block  10 . The head portion of pin  32  therefore extends upward from upper surface  16  of block  10 . When a block is installed on the wall as part of the next course, this exposed head portion of pin  32  fits into pin-receiving channel  28  in lower surface  14  of the newly placed upper block. Pin-receiving channel  28  has a width and depth sufficiently large to fit over and fully encompass the exposed head portion of pin  32 . Because the body portion of pin  32  is within pin aperture  30  of a lower block and the head portion of pin  32  is within pin-receiving channel  28  of an upper block, pin  32  interlocks the upper and lower blocks together while also providing precise front-to-back alignment between the two. 
     Referring to  FIG. 5 , a retaining wall using the retaining wall blocks of the present invention is shown. The first course of the wall (the lowest course on the bottom) is shown with four blocks placed side by side. As can be seen, when placed side by side, side legs  22  of adjacent blocks are spaced apart a distance of “a+b”, which is equivalent to distance “c” that side legs  22  are spaced apart on the same block. For a specific example, block  100  is placed next to block  110  in the first course and the distance between left side leg  101  of block  100  is spaced apart a distance of “a+b” from right side leg  111  of block  110 . 
     In general, when a second course of blocks is added on top of a first course, edge  14  of block  10  in the second course is aligned and placed in horizontal center of block  10  in the first course. This placement causes left side leg  22  of the upper block to align directly over right said leg  22  of the lower block. Specifically referring to  FIG. 5 , block  120  is placed half on top of block  100  and half on top of block  110 . Right side leg  121  of upper block  120  is aligned with and resting on left side leg  101  of lower block  100 , while left side leg  123  of upper block  120  is aligned with and resting on right side leg  111  of lower block  110 . This alignment is possible because the distance between the side legs of a single block is equivalent to the distance between the adjacent side legs of adjacent blocks. 
     Center leg  122  of upper block  120  is free-floating and not in contact with lower blocks  100  and  110  or any portion of the first course of blocks. As the wall is built, the center legs of the blocks never come into contact with the row below. This is by design, as having a free-floating center leg allows for attachment of additional stabilization means to the bottom of the center leg without preventing the blocks from resting directly on the course below. For example, soil anchors or metal ribbed or wave-shaped strips can be attached to the underside of the center legs that are not in contact with the other blocks and then buried in the backfilled area to provide additional strength to the retaining wall. Additionally, due to the cylindrical-shaped termination points of rearward extending legs  20 ,  22 , other wall and soil stabilization means can be attached that have an open socket shape that would slide down and fit around the cylindrical-shaped termination points. For example, concrete trunk blocks could be sized to run from the center leg of a block on one wall to a center leg of a block on an adjacent perpendicular wall (i.e., to stabilize a wall with a right angle corner). Alternatively, a “dead man” with an open socket shape could be slid over a cylindrical termination point of a leg and then buried in the backfilled area to provide additional strength. 
     Referring to  FIG. 6 , an alternative, novel pin-retaining system is shown. In this embodiment, block  10  has pin receiving bores  40  that are located outside of side legs  22 . Pin receiving bores  40  have a larger diameter opening on the upper side of block  10 , and then shoulder down to a narrower diameter bore that extends entirely through block  10 . This larger diameter opening on the upper side of the block affords the opportunity to use the same retaining pins with the same blocks and alternate the set back distance of the upper block. Referring to  FIGS. 7A and 7B , a side view of two course of a wall built with blocks  10  and locked in place with this novel pin-retaining system is shown with front face  12  of each block  10  on the left of both figures.  FIG. 7A  shows blocks  10  with a larger setback, and  FIG. 7B  shows blocks  10  with a smaller setback. 
     Referring specifically to  FIG. 7A , pin  44 , which has a larger diameter head portion before shouldering down to a narrower diameter body portion, is placed in bore  40  of block  10  in the upper course. As can be seen, bore  40  extends through the entire height of block  10  and the shoulder of the pin rests on shoulder  42  of bore  40  to prevent the pin from falling through bore  40 . The head of the pin is sized so as to not protrude out of the top of block  10  when resting on shoulder  42  of bore  40 . The narrower diameter body portion of pin  44  is sized to be long enough so that when on should  42  of bore  40  in block  10 , pin  44  extends vertically downward from the bottom surface of block  10 . The portion of pin  44  that extends downward from block  10  in the upper course rests behind and adjacent to rear surface  46  of block  10  in the lower course, which prevents block  10  in the upper course from moving forward with respect to block  10  in the lower course and creates a setback for front face  12  of block  10  in the upper course. 
     Referring specifically to  FIG. 7B , washer  45  is placed onto pin  44  below the larger diameter head, and pin  44  is placed in bore  40  of block  10  in the upper course. As can be seen, washer  45  rests on shoulder  42  of bore  40  to prevent the pin from falling through bore  40 , which effectively reduces the length of pin  44  extending vertically downward from the bottom surface of block  10 . Washer  45  is sized so as to not make the head of pin  44  protrude out of the top of block  10  when washer  45  is resting on shoulder  42  of bore  40 . The portion of pin  44  that extends downward from block  10  in the upper course rests in the larger diameter opening on the upper side of lower block  10  in the lower course, which prevents block  10  in the upper course from moving forward with respect to block  10  in the lower course and creates a setback for front face  12  of block  10  in the upper course. Because pin  44  in the upper block  10  is resting in the larger diameter opening of the upper side of lower block  10  rather than against rear surface  46  as in  FIG. 7A , upper block  10  sets forward in  FIG. 7B  than upper block  10  in  FIG. 7A . This setback variability allows the wall to be constructed with greater design flexibility using the same blocks and same pins. 
     Referring to  FIG. 8 , a top view of a 2-course stack of blocks is shown revealing the placement of pins  44  in the novel pin-retaining system. When the second course of blocks is stacked in brick formation (i.e., set where the center of the front face of the top block is aligned with the adjacent edges of the two lower blocks from the prior course), outside legs  22  align over outside legs  22  of the prior course of blocks. Pins  44  extend through bore  40  (as shown in  FIG. 7A ) outwardly below the block in the upper course. Pins  44  are shown resting against back surface  46  of the blocks in the lower course. Further, the block in the upper course is covering pins  44 ′ that were inserted in the blocks of the lower course, which is possible because pins  44  (and  44 ′) in this novel pin-retaining system do not extend outwardly from the top surface of the blocks. 
     As can be seen in  FIG. 8 , instead of relying upon a singular bore or channels in the bottom face of the upper blocks that have to be aligned, this pin-retaining system allows the blocks to be slid into a greater ranges of position, limited only by the distance between rearward extending legs  20  and  22  of the blocks in the lower course. This system also allows easier installation as the upper block can be set upon the lower block, and then retaining pins  44  can be placed in bores  40 . Because the bottom of the upper block is resting on the top of the lower block, pins  44  will not be able to seat completely and extend from the bottom until the upper block is slid back into place. Once the bottom of the bore hole passes behind the top of the block in the lower course, pins  44  will fall the remaining distance into place and lock the block in place. 
     Referring to  FIG. 9 , parapet wall block  60  is shown from the rear face side. Parapet wall block  60  generally comprises a block body having a front face, a rear face with a plurality of recesses  62 , which are shaped and spaced to accept the rearwardly extending support legs  20  and  22  as shown in  FIG. 1  of retaining wall block  10 . Parapet wall block  10  also has opposed first and second side surfaces, and opposed and substantially parallel upper and lower surfaces. Side surface  66  extends rearward from the front face and then tapers back at a relatively straight angle. Side surface  64  extends rearward from the front face and then curves back with a radius towards the rear face of parapet block  60 . In a preferred embodiment, parapet wall block  60  has pin-receiving channel located on the upper surface to receive and engage the retaining pins used to anchor the retaining wall blocks. 
     Referring to  FIG. 10 , a top view of one course of a parapet wall built with retaining wall blocks  10  and parapet wall blocks  60  is shown. As can be seen, parapet wall block  60  has less depth than retaining wall block  10 , which when used in conjunction with each other allows the construction of narrower freestanding walls or fences. Rearward extending legs  20  and  22  of retaining wall blocks  10  fit into recesses  62  of parapet wall blocks  60 . Where two parapet wall blocks meet and are adjacent to each other, tapered side surface  66  and curved side surface  64  combine to create a recess for center leg of  20  of retaining wall block  10 . Recesses  62  are spaced appropriately in parapet wall block  60  to correspond to the location of side legs  22  from adjacent retaining wall blocks  10 , which as discussed above in reference to  FIGS. 1 and 5 , is a distance equal to “c” or “a+b.” 
     Referring to  FIG. 11 , a parapet wall constructed from retaining wall blocks  10  and parapet wall blocks  60  is shown. Each course of a parapet wall should alternate which side has parapet wall blocks  60  and retaining wall blocks  10 . In this example, the lowest course has parapet wall blocks  60  on the near side of the wall and retaining wall blocks  10  on the far side. The middle course is opposite—retaining wall blocks  10  are on the near side and parapet wall blocks  60  are on the far side. This allows for increased stability and interlocking of the blocks as will be discussed regarding  FIG. 12 . 
     Referring to  FIG. 12 , a side view of a parapet wall constructed from retaining wall blocks  10  and parapet wall blocks  60  is shown. The lowest course of the wall has retaining wall block  10  on the left side and parapet wall block  60  on the right side. The blocks in the second course have been reversed, and parapet wall block  60  is on the left side with retaining wall block  10  on the right side. Pin  44  is seated in bore hole of retaining wall block  10  in the middle course with the portion of pin  44  that extends below bottom of retaining wall block  10  seated into channel  68  of parapet wall block  60  in the lowest course. Pin  44  locks retaining wall block  10  from the middle course to parapet wall block  60  of the lowest course and keeps retaining wall block  10  in vertical alignment with the front face of parapet wall block  60  below. And because parapet wall block  60  of the middle course is interlocked via its recesses with the legs of retaining wall block  10  of the middle course (as shown in  FIG. 10 ), parapet wall block  60  also stays in alignment with the front face of retaining wall block  10  from the course below. As courses are added to the wall, the pins  44  lock or tie the blocks to the course below and the legs in conjunction with the recesses keep the blocks on the same course in alignment. In addition to allowing dry stack with pins (as shown), the blocks can be locked into place with adhesives, core filling, steel reinforcement core filling, post tensioning systems, or a combination of these installation methods could be used in constructing the wall depending on engineering specifications. Additionally, the two block parapet wall design affords the ability to change colors, textures, and designs to the faces of the free standing wall or fence. For example, the wall could be constructed with a different color and texture on the inside of the wall versus the outside of the wall, as the two units combine to build a single width wall. 
     Referring to  FIG. 13 , the layout of how two retaining wall blocks  10  can be made in one mold cavity. Because legs  20  and  22  are offset from the center of face  12  of block  10 , the blocks can effectively mate together while maintaining similar edge terminations, which allows two blocks to be made at once. If the legs were symmetrically spaced from the center of the block, then to nest the legs together as shown in  FIG. 13 , the edges of the blocks would not be as close in alignment as is possible with the offset legs of the present invention. Being able to make two blocks with one mold increases production efficiency and also allows the space on shipping pallets to be packed more efficiently. 
     Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading the present disclosure, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.