Patent Publication Number: US-7591447-B2

Title: Wall block, system and mold for making the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. application Ser. No. 10/273,631, filed Oct. 18, 2002, now U.S. Pat. No. 7,328,537, which claims priority to U.S. Provisional Application No. 60/344,549, filed Oct. 18, 2001. This application is also a continuation-in-part of U.S. application Ser. No. 10/091,039, filed Mar. 4, 2002, now U.S. Pat. No. 7,100,886. 

   FIELD 
   The present invention relates to blocks, such as concrete blocks, for constructing walls, and more particularly to blocks employing a pin and slot system for interconnecting blocks stacked on top of each other in a wall, and to a mold for making such blocks. 
   BACKGROUND 
   Natural stone blocks cut from quarries have been used for a number of years to assemble walls of various types, including ornamental walls for landscaping purposes. Natural blocks have unique sizes, differences in shape and differences in appearance. However, construction of walls using such blocks requires significant skill to match, align, and place blocks so that the wall is erected with substantially uniform courses. While such walls provide an attractive ornamental appearance, the cost of quarried stone and the labor to assemble the stone blocks are generally cost prohibitive for most applications. 
   An attractive, low cost alternative to natural stone blocks are molded concrete blocks. In fact, there are several, perhaps hundreds, of utility and design patents which relate to molded blocks and/or retaining walls made from such blocks. Most prior art walls, however, are constructed from dimensionally identical blocks which can only be positioned in one orientation within the wall. Thus, a wall made from such molded or cast blocks does not have the same random and natural appearance of a wall made from natural stone blocks. 
   Accordingly, there is a need for new and improved molded blocks, methods for forming blocks, and block systems and methods, for constructing walls that have a more natural appearance than walls constructed using molded blocks, block systems, and molded block methods of the prior art. 
   SUMMARY 
   According to one aspect, the present disclosure relates to embodiments of a wall block and block systems employing a pin and slot connection system for interconnecting blocks stacked on top of each other in a wall. 
   A wall block, according to one embodiment, includes an upper surface spaced apart from a substantially parallel lower surface, first and second, substantially parallel faces, and first and second, substantially straight side surfaces extending between respective ends of the first and second faces. The first face of the block has a surface area greater than the second face. The block is adapted to be “reversible” in a wall, that is, either the first face or the second face can serve as the exposed face in one side of the wall, thereby giving the appearance that the wall is constructed from two differently sized blocks. In certain embodiments, both faces have a roughened or split look resembling natural stone. 
   To interconnect vertically adjacent blocks (i.e., blocks stacked on top of each other in a wall), the upper surface of the block is formed with at least two pin holes and the lower surface is formed with at least one pin-receiving slot or channel. A first pin hole is spaced a first distance from a longitudinal axis extending between the side surfaces and bisecting the upper surface. A second pin hole is located on the same side of the longitudinal axis as the first pin hole, but is spaced a second distance, greater than the first distance, from the longitudinal axis. Also, the first pin hole is offset from the second pin hole in the direction of the longitudinal axis so as to minimize breakage of the concrete between the pin holes if the block is tumbled. 
   In particular embodiments, the lower surface of the block is formed with a first pin-receiving slot and a second pin-receiving slot extending parallel to the first pin-receiving slot. The pin-receiving slots are located on opposite sides of a longitudinal axis extending between the side surfaces and bisecting the lower surface. The upper surface of the block further includes third and fourth pin holes located on the opposite side of the longitudinal axis from the first and second pin holes. The fourth pin hole is spaced farther from the longitudinal axis than the third pin hole and is offset from the third pin hole in the direction of the longitudinal axis. The pin holes and the pin-receiving slots permits vertical, set forward, or set back placement of blocks in a course relative to blocks in an adjacent lower course. 
   According to another aspect, a block system can be provided that includes plural similarly shaped, but differently sized blocks. In one embodiment, for example, such a block system includes a small, medium, and large block. Each block has the same depth and height, but different lengths. Each block has converging side walls and is reversible so that each block can be used to provide at least two different sized faces in the surface of a wall. The angles of convergence of the side walls of each block are substantially the same so that placing blocks of any size side-by-side in a course, with every other block being reversed 180 degrees forms a substantially straight wall. Additionally, the opposing faces of each block can be provided with a roughened surface texture. 
   The small, medium, and large blocks can be formed in a mold that does not require splitting of the blocks or removing sacrificial portions from the blocks to achieve a roughened surface texture resembling natural stone on two opposing faces of each block. In an illustrated embodiment, the mold has first and second end walls, first and second side walls extending between respective ends of the end walls, and a first divider wall extending between the first and second side walls and separating the mold into a first mold portion and a second mold portion. The first mold portion comprises a first cavity for forming the large block. A second divider wall in the second mold portion extends between the first end wall and the first divider wall so as to define a second cavity for forming the medium block and a third cavity for forming the small block. The end walls and the first divider wall are configured to form roughened surface textures on two surfaces of each of the small, medium, and large block as the blocks are removed from the mold cavities in an uncured state. 
   In particular embodiments, the first end wall has inwardly extending projections for contacting adjacent block surfaces of the medium block in the second mold cavity and the small block in the third cavity. The second end wall has inwardly extending projections for contacting an adjacent block surface of the large block in the first cavity. One surface of the first divider wall has inwardly extending projections for contacting an adjacent block surface of the large block in the first cavity. Another surface of the first divider wall has inwardly extending projections for contacting adjacent block surfaces of the medium and small blocks in the second and third cavities. As the mold is moved vertically with respect to the uncured blocks for removing them from the mold cavities, the projections on the mold walls scour or abrade the adjacent block surfaces, thereby creating an irregularly roughened surface for those sides of the blocks. 
   The foregoing and other features and advantages of the invention will become more apparent from the following detailed description of several embodiments, which proceeds with reference to the accompanying figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a bottom perspective view of a wall block, according to one embodiment. 
       FIG. 2  is a bottom plan view of the block of  FIG. 1 . 
       FIG. 3  is a side elevational view of the block of  FIG. 1 . 
       FIG. 4  is a bottom plan view of another embodiment of a wall block. 
       FIG. 5  is a side elevational view of the block of  FIG. 4 . 
       FIG. 6  is a bottom plan view of yet another embodiment of a wall block. 
       FIG. 7  is a side elevation view of the block of  FIG. 6 . 
       FIG. 8  is a vertical sectional view of a wall, from front to back, constructed from like blocks having the configuration of the blocks shown in  FIGS. 1-3 . 
       FIG. 9  is a bottom perspective view of another embodiment of a wall block. 
       FIG. 10  is a top plan view of the block of  FIG. 9 . 
       FIG. 11  is a vertical sectional view of a wall constructed from like blocks having the configuration of the blocks of  FIGS. 9 and 10 , wherein one such block is positioned in a vertical orientation as a jumper. 
       FIG. 12  is a perspective view of a connecting pin, according to one embodiment, that can be used to interconnect vertically adjacent blocks. 
       FIG. 13  is a partial, schematic plan view of the upper surface of a block showing a connecting pin inserted in a pin hole of the block. 
       FIGS. 14A-14D  are front elevational views of walls constructed from different combinations of the blocks shown in  FIGS. 1-7 . 
       FIG. 15  is a top plan view of a curvilinear wall constructed from the blocks shown in  FIGS. 1-7 . 
       FIG. 16  is a top plan view of a wall constructed from the blocks shown in  FIGS. 1-7  and having two straight wall portions intersecting at a 90 degree corner. 
       FIG. 17  is a top plan view of a corner block, according to one embodiment, that can be used for forming 90 degree corners in walls. 
       FIG. 18  is a front elevational view of a wall constructed from various blocks of a block system comprising a first set of small, medium, and large blocks and a second set of small, medium, and large blocks, wherein the blocks of second set have a height that is greater than the height of the blocks of the first set. 
       FIG. 19  is a top plan view of a three-block module that comprises a small, medium, and large block. 
       FIG. 20  is a top plan view of mold that can be used to form a small, medium, and large block, according to one embodiment. 
       FIG. 21  is a front elevational view of one of the end walls of the mold shown in  FIG. 20 . 
       FIG. 22  is a cross-sectional view of the end wall of  FIG. 21  taken along line  22 - 22  of  FIG. 21 . 
       FIG. 23  is a cross-sectional view of the end wall of  FIG. 21  taken along line  23 - 23  of  FIG. 21 . 
       FIG. 24  is a schematic, vertical sectional view of the mold of  FIG. 21  illustrating a method for forming a small, medium, and large block with the mold. 
       FIG. 25  is a schematic, vertical sectional view similar to  FIG. 24  showing blocks being removed from the mold. 
       FIG. 26  is a front elevational view of a mold wall for creating a roughened surface texture on a block surface, according to another embodiment. 
   

   DETAILED DESCRIPTION 
   As used herein, the singular forms “a,” “an,” and “the” refer to one or more than one, unless the context clearly dictates otherwise. As used herein, the term “includes” means “comprises.” 
   In the following description, “upper” and “lower” refer to the placement of a block in a retaining wall. The lower, or bottom, surface of a block is placed such that it faces the ground. In a retaining wall, one row of blocks is laid down, forming a lowermost course or tier. An upper course or tier is formed on top of this lower course by positioning the lower surface of one block on the upper surface of another block. Additional course may be added until a desired height of the wall is achieved. Typically, earth is retained behind a retaining wall so that only a front surface of the wall is exposed. A free-standing wall (i.e., one which does not serve to retain earth) having two exposed surfaces may be referred to as a “fence.” 
   According to a first aspect, a block for constructing a wall is configured to be reversible, that is, the block has at least two surfaces of different dimensions, each of which can be used as the exposed face in a surface of a wall. According to another aspect, a pin and slot connection system for interconnecting blocks of adjacent courses permits alignment of blocks directly over one another, set forward, or set backward relative to one another so that either vertical or non-vertical walls may be constructed. 
   Referring first to  FIGS. 1-3 , there is shown a block  10  according to one representative embodiment.  FIG. 1  is a bottom perspective view of the block  10 ,  FIG. 2  is a bottom plan view of the block  10 , and  FIG. 3  is a side elevational view of the block  10 . The illustrated block  10  is generally trapezoidal and comprises opposed side walls or side surfaces  12 , generally parallel bottom and top surfaces  14 ,  16 , respectively, and generally parallel first and second faces  18 ,  20 , respectively. The side walls  12  taper inwardly, or converge, as they extend from the first face  18  to the second face  20  so that acute angles  8  are formed between the first face  18  and side walls  12  and obtuse angles  6  are formed between the second face  20  and side walls  12 . Hence, the surface area of the first face  18  is greater than the surface area of the second face  20 . Alternatively, the block can have one side wall that is generally perpendicular to the first and second faces. In other embodiments, the block can have other geometric shapes, such as a square or rectangle. 
   Desirably, the surface texture of the first face  18  is the same as that for the second face  20 . In this manner, the block  10  is “reversible,” that is, either the first face  18  or the second face  20  can serve as the exposed face on one side of a wall. Since the first face  18  is larger than the second face  20 , a wall constructed from such blocks takes on a more random, natural appearance, than a wall in which the exposed faces of all blocks are equal in size. In the illustrated embodiment, for example, both the first face  18  and the second face  20  are provided with a roughened, or split look (known as a “split face” or “rock face”) (as shown in  FIG. 1 ) to contribute to the natural appearance of the wall. As used herein, a “roughened” block surface refers to a surface texture that can be formed by splitting two conjoined blocks or splitting a sacrificial portion from a block, or by creating such a surface texture on an uncured block as it is removed from a mold, such as described in detail below. The block also may be “tumbled” to round the edges and corners of the block, as generally known in the art. Alternatively, the block  10  may be molded so that one or both of faces  18 ,  20  have a smooth, rather than a rough, surface. 
   Pin-receiving slots (also referred to herein as troughs or channels)  22 ,  24  formed in the bottom surface  14  extend longitudinally of the block between the side walls  12 , but terminate short of the side walls as shown. This minimizes breakage of the blocks if they are tumbled. The slots  22 ,  24  allow a block to be shifted longitudinally in a course either to the left or the right so that the block is longitudinally offset from a block in an adjacent lower course. Thus, a block in an upper course can be positioned to span two blocks in a lower course and be connected to them with a connected pin extending into one of the slots from one or both of the blocks in the lower course. 
   In other embodiments, a block can be provided with slots that extend completely across the length of the block between the side walls (such as slots  322 ,  324  of block  300  shown in  FIGS. 9 and 10 ). This allows the block to be stacked on its side in a wall as a “vertical jumper,” as further described below. 
   The block  10  may also have a centrally located core (not shown) between the channels  22 ,  24  to reduce the overall weight of the block  10 . The core can be a semi-hollow or partial core that extends from the bottom surface partially through the block (e.g., core  328  of block  300  shown in  FIGS. 9 and 10 ). Alternatively, the core may be a full core, that is, a core that extends completely through the block. When forming courses with blocks having full cores, the cores can be filled with a fill material, such as gravel, to prevent migration of earth into the core. In addition, the block  10  may have optional hand holds or handles  30  defined in the bottom surface  14  at each side wall  12  to facilitate carrying or placement of the block  10 . 
   As best shown in  FIG. 2 , the block  10  has a plurality of pin-receiving apertures such as pin holes  26   a - 26   l  formed in the upper surface  16 . The pin holes  26   a - 26   l  are shown as extending completely through the block, although this is not a requirement. In an alternative embodiment, the pin holes  26   a - 26   l  extend partially through the block from the upper surface  16 . In any event, the pin holes  26   a - 26   l  are arranged in four rows extending substantially parallel to the first and second faces  18 ,  20 . Each row in the illustrated embodiment has three such pin holes  26 , although the number of pins holes  26  in each row, as well as the number of rows of pin holes  26 , may vary. 
   The pin holes in the illustrated embodiment have a rectangular cross-sectional profile. Also, the pin holes desirably are elongated in the direction of the length of the block. This allows the position of a pin within a pin hole to be shifted longitudinally toward either side wall  12  so that the pin can be easily aligned with a channel of an overlying block. 
   In other embodiments, the pin holes can have other geometric shapes such as circles, ovals, squares, triangles, or various combinations thereof. It has been found that when forming blocks having circular pin holes, concrete tends to build up or collect in the pin holes. On the other hand, rectangular pin holes, such as shown in the illustrated embodiments, and square pin holes are advantageous in that they minimize or totally prevent the build up of concrete in the pin holes. 
   Pins holes  26   a ,  26   b  and  26   c  comprise an outer row  58  of pin holes which are vertically aligned with the channel  24 . Pin holes  26   j ,  26   k  and  26   l  comprise an outer row  60  of pin holes which are vertically aligned with the channel  22 . Desirably, pin holes  26   a ,  26   b ,  26   c  and  26   j ,  26   k ,  26   l  are positioned so as to have one side tangent to the inner wall of a respective channel  24 ,  22 . This, as explained in greater detail below, prevents earth retained behind the wall, which exerts forward pressure on the wall, from upsetting the vertical alignment of the blocks in the wall. The outer rows  58 ,  60  of pin holes are equally spaced a predetermined first distance from a longitudinal axis, or plane, L, extending through the block halfway between the first and second faces  18 ,  20  (that is, plane L bisects the block between its faces  18 ,  20 ). Pin holes  26   d ,  26   e  and  26   f  comprise an inner row  62  of pin holes between the outer row  58  and the plane L. Pin holes  26   g ,  26   h  and  26   i  comprise an inner row  64  of pin holes between the outer row  60  and the plane L. The inner rows  62 ,  64  are equally spaced from the plane L a predetermined second distance that is less than the distance between each outer row  55 ,  60  and the plane L. 
   As further shown in  FIG. 2 , the pin holes  26   a ,  26   b , and  26   c  of outer row  58  are longitudinally offset from the pins holes  26   d ,  26   e , and  26   f , respectively, of inner row  62 . In a similar fashion, the pin holes  26   j ,  26   k , and  26   l  of outer row  60  are longitudinally offset from the pin holes  26   g ,  26   h , and  26   i , respectively, of inner row  64 . Advantageously, staggering the placement of pin holes in the manner shown in  FIG. 2  minimizes breakage of the concrete separating pairs of adjacent pin holes (e.g., pin hole  26   a  and pin hole  26   d ) when the block is subjected to tumbling. 
     FIG. 12  illustrates a pin  32 , according to one embodiment, that can be used to interconnect blocks in a wall. The illustrated pin  32  includes a generally cylindrical upper portion, or head,  80 , and a generally cylindrical lower portion  82 . The lower portion  82  can include a plurality of circumferentially spaced, elongate ribs  84  that extend longitudinally of the pin. The pin  32  also can be formed with radially extending, annular rib, or apron,  86  adjacent the upper ends of ribs  84 . 
   When constructing a wall from a plurality of like blocks  10 , the lower portion  82  of a pin  32  is inserted into any one of pin holes  26  in the upper surface of a block. The upper portion  80  of the pin is positioned in one of the slots  22 ,  24  of an overlying block. As depicted in  FIG. 13 , the ribs  84  function to frictionally engage the front and rear vertical surfaces of the pin hole  26 . The apron  86  (not shown in  FIG. 13 ) of the pin is sized to engage the upper surface  16  of the block and therefore assists in maintaining the vertical position of the pin relative to the pin hole. Since the pin hole is elongated, the pin  32  can be shifted longitudinally in the pin hole to the left or the right to assist in aligning the pin with a slot  22 ,  24  of an overlying block. 
     FIG. 8  illustrates a vertical cross-sectional, side elevational view of a wall made from a plurality of like blocks having the same general shape as block  10  shown in  FIGS. 1-3 . The wall has a front, exposed surface  54  and a rear surface  56 , behind which earth may be retained. Of course, if the wall is a freestanding wall, then both the first and second surfaces  54 ,  56  are exposed. The first, lowermost course  36  of such a wall typically is laid in a trench (not shown) and successive courses  40 ,  44 ,  48  and  52  are laid one on top of the other. Either the first or second face  18 ,  20  of any one block may be used to form the front surface  54  of the wall. Pins  32  can be used to hold the courses of blocks in place, although in some applications, such as where a wall is relatively short in height, the weight of the blocks may be sufficient to hold the blocks in place without the use of pins. 
   When constructing engineered or structural walls (e.g., walls typically built above a height of about four feet), a suitable geogrid can be placed between courses of blocks to extend into the hillside or earth behind the wall to give the wall sufficient strength and stability. Blocks having full cores (i.e., a core extending completely through the block) are preferred (although not required) when using geogrid because the fill material placed in the cores assists in retaining the geogrid between adjacent courses. 
   As mentioned, the pin and slot connection system permits vertical, set forward, or set back placement of blocks in a course relative to the blocks in an adjacent lower course. As shown in  FIG. 8 , for example, a block  38  in the second course  40  is vertically aligned with a block  34  in the first, lowermost course  36 . The lower portion of a pin  32   a  in this illustration is positioned in a pin hole  26  of the outer row  58  of block  34 . The head of pin  32   a  is positioned in the slot  24  of block  38 . As noted above, the pin holes of the outer rows  58 ,  60  of pin holes are positioned so as to have one side tangent to the inner wall of a channel  22 ,  24  (as best shown in  FIG. 2 ). As depicted in  FIG. 8 , this allows the head of pin  32   a  to contact an inner surface of the slot  24 . This contact between the head of the pin and the inner surface of the slot resists any forward movement of block  38  caused by the pressure of earth retained behind the wall so as to maintain the desired vertical alignment of block  38  with respect to block  34 . To ensure that the wall is sufficiently stable, at least one pin is used to interconnect each block of one course with a block of an adjacent lower course (as shown in  FIG. 8 ), although more than one pin may be used for redundancy or for interconnecting a lower block with two overlying blocks. 
   Block  42  of the third course  44  is in a set back relation to block  38  of the second course  40 . In this position, slot  24  of block  42  is aligned over the inner row  62  of pin holes of block  38  with the lower portion of a pin  32   b  received in a pin hole  26  of block  38  and the head of pin  32   b  received in slot  24  of block  42 . Block  46  of the fourth course  48  is in a set forward relation to block  42  of the third course  44  with slot  24  of block  46  being aligned over an inner row  64  of pin holes  26  of block  42 . Block  46  is also reversed in the wall so that its second face  20  is exposed in the first surface  54  of the wall and its first face  18  forms part of the second surface  56  of the wall. A pin  32   c  is partially received in a pin hole  26  of block  42  and slot  24  of block  46  to hold these blocks together. Block  50  of the fifth course  52  is in a set forward position with respect to block  46  of the fourth course  48 , with slot  22  of block  50  being aligned over an inner row  62  of pin holes  26  of block  46 . A pin  32   d  is partially received in a pin hole  26  in the upper surface  16  of block  46  and slot  22  of block  50 . 
     FIGS. 9 and 10  illustrate a block  300 , according to another embodiment, having first and second faces  318  and  320 , respectively, bottom and top surfaces  314  and  316 , respectively, and side surfaces  312  extending between respective ends of the first and second faces  318 ,  320 . The block  300  includes a first outer row  358  of pin holes  326   a ,  326   b , and  326   c , a second outer row  360  of pin holes  326   j ,  326   k , and  326   l , a first inner row  362  of pin holes  326   d ,  326   e , and  326   f , and a second inner row  364  of pin holes  326   g ,  326   h , and  326   i . In this embodiment, the pin holes are aligned in rows extending from a first face  318  to a second face  320 . Thus, pin holes  326   a ,  326   d ,  326   g , and  326   j  are aligned in a first row; pin holes  326   b ,  326   e ,  326   h , and  326   k  are aligned in a second row; and pin holes  326   c ,  326   f ,  326   i , and  326   l  are aligned in a third row. 
   The block  300  is formed with channels  322  and  324  that extend longitudinally of the block and intersect the side walls  312  as shown. The block  300  also is formed with a centrally located core  328  that extends from the bottom surface  314  partially through the block, and hand holds  330  defined in the bottom surface  314  at each side wall to facilitate carrying or placement of the block. 
   The block  300  may be configured to be placed in a vertical orientation in a wall, as a “jumper” block. When used in this way, the side walls  312  serve as the top and bottom of the block in a wall and the bottom surface  314  and the top surface  316  serve as the side walls of the block in a wall. The length of the first face  318  therefore is the effective height of the block when used as a jumper. 
   Because the side walls  312  are angled with respect to the first and second surfaces  318 ,  320 , the block  300 , when used as a jumper, would be tilted slightly from a vertical plane of the wall. Also, a block placed on top of the upwardly facing side wall  312  of the jumper would be supported at an angle. Thus, to support the jumper and any overlying block in a vertically upright position, pin-receiving slots  366  and  368  are formed in the side walls  312  proximate the ends of channel  322 . The widths w 1  of pin-receiving slots  366  and  368  are desirably, although not necessarily, dimensioned to form a frictional fit with the lower portion  82  of a connecting pin  32 . When the block is turned on its side for vertical placement in a wall, pins are inserted into slots  366  and  368 , which then support the block and any overlying block in a vertically upright position. Pin-receiving slots  370  and  372  are similarly formed in the side walls  312  proximate the ends of channel  324 . Slot  370  serves as a pin hole for frictionally engaging the lower portion of a pin. Slot  372  has a width equal to that of channel  24  and serves as an extension of channel  324  to receive the upper portion of a pin. 
   Where a block is configured to be used as a jumper (such as block  300 ), the length of the first face  318  desirably is a multiple of the height of the block. For example, if the length of the first face  318  is twice the height of the block, then a jumper will span two horizontally oriented blocks, or courses, in the vertical direction. Thus, as explained below with respect to  FIG. 11 , it is still possible to achieve a level upper surface of the wall. 
     FIG. 11  illustrates the use of block  300  as a jumper. A wall in this illustration includes a first block  300 ′ in a first course, a second block  300 ″ in a second course and a third block  300 ′″ in a third course. Blocks  300 ′,  300 ″ and  300 ′″ are of the same general shape as block  300  of  FIGS. 9 and 10 . The second block  300 ″ is turned on its side so that one of its side walls  312  is adjacent the upper surface  316  of the first block  300 ′ and the other is adjacent the lower surface  314  of the third block  300 ′″. 
   As shown in  FIG. 11 , the lower portion  82  of a pin  32   a  is inserted into slot  368  of the second block  300 ″ and the head  80  of the pin  32   a  contacts the upper surface  316  of the first block  300 ′ to support the downwardly facing side wall  312  of block  300 ″ (i.e., the side wall  312  serving as the bottom of block  300 ″) at a position above the upper surface  316  of block  300 ′. The head  80  of the pin  32   a  is long enough to support the second block  300 ″ in a vertically upright position. 
   A pin  32   b  inserted into slot  366  of block  300 ″ supports block  300 ′″ in a level, vertically upright position. Since pin  32   b  is aligned with channel  322  of block  300 ′″, the head  80  of pin  32   b  should have a thickness or diameter greater than the width of channel  322  to prevent insertion of the pin therein. Alternatively, if pin  32   b  is a standard sized pin (i.e., a pin having a diameter that is less than the width of channel  322 ) a small section of pipe, having a diameter larger than the width of the channel  322 , can be placed over the head  80  of pin  32   b  to prevent insertion of pin  32   b  into channel  322  of block  300 ′″. In an alternative embodiment, slot  366  is offset slightly from channel  322  towards the first face  20  or second face  18  so that a pin inserted into slot  366  is not vertically aligned with a channel in an overlying block. 
   The lower portion  82  of a pin  32   c  is received in a pin hole in the upper surface of block  300 ′ and the head  80  of pin  32   c  is received in slot  372  of jumper block  300 ″ to connect blocks  300 ′ and  300 ″. The lower portion  82  of a pin  32   d  is received in slot  370  of block  300 ″ and the head  80  of pin  32   d  is received in a respective channel  324  in block  300 ′″ to connect blocks  300 ″ and  300 ′″. 
   As shown, a course may comprise blocks of different effective “heights,” thereby further contributing to the random appearance of the wall. In this illustration, the effective height of the jumper block  300 ″ (i.e., the length of the first face  318 ) is equal to the overall height of two horizontally oriented blocks stacked on top of each other. Because the height of the jumper block  300 ″ is a multiple of the height of the other blocks in the wall, it is possible to achieve a level upper surface of the wall. 
   A block system can be provided that includes plural similarly shaped, but differently sized blocks. In one embodiment, for example, such a block system includes a large block comprising the block  10  shown in  FIGS. 1-3 , a medium block comprising the block  100  shown in  FIGS. 4 and 5 , and a small block comprising the block  200  shown in  FIGS. 6 and 7 . Each block is of the same general shape. The medium block  200  ( FIGS. 4 and 5 ), like the large block  10 , has a first face  118 , a second face  120  and converging side walls  112 . Similarly, the small block  200  ( FIGS. 6 and 7 ) has a first face  218 , a second face  220  and converging side walls  212 . 
   The surface area of the first face of each block is larger than the surface area of its second face. Desirably, although not necessarily, each block is the same in depth (i.e., the distance from the first face to the second face of a block, for example, between the first face  18  and the second face  20  of the large block  10 ) and in height (i.e., the distance from the upper surface to the lower surface of a block). The length of the first face  18  of the large block  10  (i.e., the distance the first face  18  extends between side walls  12 ) desirably is equal to or a multiple of the height of the blocks so that it is possible to achieve a level top surface of a wall if the large block is adapted to be used as a jumper. 
   As shown in  FIG. 4 , the medium block  100  is formed with a first row of pin holes  126   a  and  126   b ; a second row of pin holes  126   c  and  126   d ; a third row of pin holes  126   e  and  126   f ; and a fourth row of pin holes  126   g  and  126   h . As shown, the pin holes of each row can be positioned in a staggered or offset relationship with respect to the pin holes of an adjacent row. The medium block  100  in the illustrated embodiment also is formed with hand holds  130 , slots  122   a  and  122   b  adjacent the second face  120 , and slots  124   a  and  124   b  adjacent the first face  118 . 
   A splitting notch  132  extending in the direction of the block depth can be formed in the bottom surface  114 . The notch  132  in the illustrated block is positioned equidistant from the side walls  112  and can be used to split the block into two smaller blocks of equal size, each having a side wall that is perpendicular to its first and second faces. One or both of the resulting smaller blocks can be used as a corner block for forming 90 degree corners in a wall, as described in greater detail below. In an alternative embodiment, the notch can be positioned closer to one of the side walls  112  so that the block can be split into two blocks of unequal size. In another embodiment, a splitting notch is not provided, in which case the block can be formed with two continuous pin-receiving slots, in the same manner as the large block  10 , instead of four slots. Further, a splitting notch can be provided in one or both of the small and large blocks. 
   As shown in  FIG. 6 , the small block  200  in the illustrated embodiment is formed with hand holds  230 , slots  222  and  224 , and a pin hole  226 . In other embodiments, however, the small block can be provided with any number of pin holes arranged in one or more rows. 
   The block system can be used to construct various straight or curvilinear walls of various radii. The angles of convergence of the side walls of each block in the three-block system desirably are substantially the same. Thus, placing blocks of any size side-by-side in a course, with every other block being reversed 180°, forms a substantially straight wall. 
     FIG. 16 , for example, illustrates a top plan view of one example of a wall having two straight runs intersecting at a 90 degree angle. Each course is formed by placing small, medium and large blocks side-by-side with every other block being reversed so that the tapered side walls of each block is complemented by a side wall of an adjacent block to form a substantially straight wall. As shown, because the angle of convergence of the side walls of each block is the same, a closed joint is formed between the contacting side walls of adjacent blocks so that there are no spaces between adjacent blocks at the front and back surfaces of the wall. This allows the block system to be used for constructing a free-standing wall, or fence, where both sides of the wall are exposed. Blocks  140 , which can be formed by splitting a medium block  100 , are used to form a 90 degree corner at the intersection of the two sections of the wall. 
   Because the first face of each block is greater in surface area than the second face, each block can be used to provide at least two differently sized faces in the surface of a wall. Thus, a wall constructed from the small, medium, and large blocks has the appearance of a wall constructed from six differently sized blocks. The small, medium, and large blocks can be randomly positioned in each course, or alternatively, they can be used to create various patterns in the exposed surface of a wall.  FIGS. 14A-14D , for example, illustrate four different patterns that can be created in a wall using the small, medium, and large blocks. Although not apparent in  FIGS. 14A-14D , the walls may include blocks that are vertically aligned over one another, set forward or set back. See, for example,  FIG. 8 . 
     FIG. 15  shows a curved wall formed by repeating sequences of a large block  10 , a medium block  100 , and a small block  200 . Other block combinations can be used to form curved walls of different radii. For example, curved walls can be constructed using all small blocks  200 , all medium blocks  100 , or all large blocks  10 . Also, curved walls can be formed by alternating small blocks and large blocks, by alternating medium blocks and large blocks, or by alternating small blocks and medium blocks. 
   The dimensions of the small, medium and large blocks may vary. In one specific and exemplary embodiment of a three-block system, the first face  18  of the large block  10  is about 16 inches in length and the second face  20  is about 14 inches in length. The first and second faces  118 ,  120  respectively, of the medium block  100  are about 12 and 10 inches, respectively, in length. The first and second faces  218 ,  220 , respectively, of the small block  200  are about 6 and 4 inches, respectively, in length. The height of each block is about 6 inches. Generally, increasing the depth of a block increases wall stability and hence, the overall allowable height of the wall. Also, if geogrid is used, increasing block depth increases the connection strength between a sheet of geogrid and the two courses that are stacked directly above and below the geogrid sheet. The depth of each block desirably is at least about 10.25 inches, which typically allows construction of 3 foot high walls without the use of geogrid. In other embodiments, the depth of each block is at least about 11.5 inches for constructing walls up to at least 4 feet in height without the use of geogrid. In still other embodiments, the depth of each wall is at least 12 inches for even greater wall stability and geogrid connection strength. The foregoing dimensions have been found to permit ease of handling and withstand the impact forces of the tumbling process. Additionally, a small, medium, and large block having the foregoing dimensions can be formed together in a mold that can be used with a standard size block-making machine. 
   Of course, those skilled in the art will realize, these specific dimensions (as well as other dimensions provided in the present specification) are given to illustrate the invention and not to limit it. These dimensions can be modified as needed in different applications or situations. 
   In alterative embodiments, one or more of the small, medium, and large blocks can be adapted to be used as a vertical jumper. In one system, for example, the large block can comprise the block  300  shown in  FIGS. 9 and 10 , which can be used as a vertical jumper as described above. However, in other systems, it is contemplated that either the small block or the medium block, or both, are configured to be used as a vertical jumper. 
     FIG. 17  illustrates one example of a corner block  400  that can be used in lieu of splitting a medium block  100  to form a 90 degree corner in a wall. The illustrated corner block  400  includes a first face  410  and a second face  412 , which extend perpendicularly to each other to form a 90 degree corner. The first and second faces  410 ,  412 , respectively, typically are exposed faces, and as such, they may be provided with a roughened, or split, surface, to contribute to the natural appearance of the wall. A third face  414  is oriented at an obtuse angle  418  relative to the second face  412 . A fourth face  416  is oriented at an acute angle  420  relative to the first face  410 . Angles  418  and  420  of the corner block  400  are equal to the included angles  6  and  8 , respectively, of the small, medium and large blocks to complement the tapered side wall of an adjacent block in a course. The corner block  400  also can include pin holes  426  in the upper surface and a generally L-shaped channel  428  in the lower surface. 
   A block system according to another embodiment comprises a first set of blocks comprising a small, medium, and large block and a second set of blocks comprising a small, medium, and large block. The small block of each set has the same configuration as the block  200  shown in  FIGS. 6 and 7 ; the medium block of each set has the same configuration as the block  100  shown in  FIGS. 4 and 5 ; and the large block has the same configuration as the block  10  shown in  FIGS. 1-3 . The dimensions of the small block, medium block, and large block of the first set are equal to the dimensions of the small block, medium block, and large block, respectively, of the second set, except that the blocks of the second set are greater in height than the blocks of the first set. Desirably, the height of the blocks of the second set is a multiple of the height of the blocks of the first set to permit the construction of a wall having a level or planar top surface. Within each set, the blocks have the same depth (i.e., the distance between the first face and the second face of a block) and height (i.e., the distance between the upper and lower surface of a block). Since each block can be used to provide at least two differently sized faces in the surface of a wall, a wall constructed from the small, medium and large blocks of both sets has the appearance of a wall constructed from twelve differently sized blocks. 
     FIG. 18  illustrates one example of a portion of a wall constructed from small, medium and large blocks  10 ,  100 ,  200 , respectively, of a first set of blocks and small, medium, and large blocks  10 ′,  100 ′, and  200 ′ of a second set of blocks. In this illustration, the height of the blocks of the second set is twice the height of the blocks of the first set. Thus, as shown in  FIG. 18 , the courses of a wall may comprise blocks of different heights so as to contribute to the random, natural appearance of the wall and a level upper surface of the wall can be achieved by selective stacking of the blocks. This also can be accomplished with any two sets of blocks in which the height of the blocks of one set is a multiple of the height of the blocks of another set. For example, the height of the blocks of the first set can be three times the height of the blocks of the second set. 
   In addition, any of the blocks of the first and second sets can be configured for use as a jumper block.  FIG. 18 , for example, shows two larges block  10  of the first set and a large block  10 ′ of the second set used as a jumper. The length of the first faces  18  and  18 ′ of large blocks  10  and  10 ′, respectively, desirably is equal to the overall height of several horizontally oriented blocks stacked on top of each other. In this illustration, for example, the length of the first faces of the large blocks is equal to the height of two horizontally stacked blocks of the second set or four horizontally stacked blocks of the first set. 
   In a specific and exemplary implementation of the present embodiment, a first set of blocks comprises a small, medium and large block having a height of about 8 inches, and a second set of blocks comprises a small, medium and large block having a height of about 4 inches. The first and second faces of the large block in each set are about 16 and 14 inches, respectively, in length. The first and second faces of the medium block in each set are about 12 and 10 inches, respectively, in length. The first and second faces of the small block in each set are about 6 and 4 inches, respectively, in length. The depth of each block of the first and second sets is about 11.5 inches. 
   Blocks  10 ,  100 , and  200  may be formed in a single mold as a three-block module, such as shown in  FIG. 19 . A substantially v-shaped notch  504  defines a groove or split line for separating the large block  10  from the small and medium blocks,  100 ,  200 , respectively. These blocks may be split along notch  504  in any conventional manner, such as with a conventional hammer and chisel or a block-splitting machine, as known in the art. Sacrificial portions (not shown) may be molded to faces  20 ,  120  and  218 , which are removed to provide the split look on those faces, as known in the art. During the casting process, a divider plate can be positioned between small block  200  and medium block  100  at  506  to provide a smooth surface on the abutting side wall  212  of block  200  and abutting side wall  112  of block  100 . 
   In another embodiment, blocks  10 ,  100 , and  200  can be formed in a mold that does not require splitting of the blocks or removing sacrificial portions from the blocks to achieve a “roughened” surface texture resembling natural stone or a split look on two opposing surfaces of each block.  FIG. 20  shows one embodiment of such a mold, indicated generally at  1000 , that can be used to form blocks  10 ,  100 , and  200 , with each block having their respective first and second faces roughened to resemble natural stone. 
   As shown in  FIG. 20 , the illustrated mold  1000  includes first and second end walls  1002  and  1004 , respectively, and first and second side walls  1006  and  1008 , respectively, extending between respective ends of the end walls. A divider wall  1010  extends between the side walls  1006  and  1008  so as to divide or partition the mold  1000  into two mold portions. Although not a requirement, the divider wall  1010  in the illustrated embodiment is positioned midway between the end walls  1006 ,  1008 , and therefore bisects the mold into two equal mold portions. The divider wall  1010  can comprise first and second plates  1012  and  1014 , respectively, placed in back-to-back relationship as shown, although in other embodiments the divider wall can have a unitary or one-piece construction. 
   A first mold portion is defined by the second plate  1014 , the first end wall  1002 , and the respective portions of side walls  1006 ,  1008  extending therebetween, and a second mold portion is defined by the first plate  1012 , the second end wall  1004 , and the respective portions of side walls  1006 ,  1008  extending therebetween. The first mold portion comprises a first mold cavity  1026  for forming the large block  10 . A divider wall  1016  extends between the first plate  1012  and the second end wall  1004  so as to define a second mold cavity  1028  for forming the medium block  100  and a third mold cavity  1030  for forming the small block  200 . The divider wall  1016  extends at an angle with respect to the plate  1012  and the end wall  1004  that is equal to angles  6  and  8  of the blocks ( FIGS. 2 ,  4 , and  6 ). 
   Mold inserts  1018  and  1020  can be positioned in the first mold cavity  1026  to form the converging side walls  12  of the large block  10 . Similarly, mold inserts  1022  and  1024  can be positioned in the second and third mold cavities  1028 ,  1030 , respectively to form respective side walls of the medium and small blocks. The mold  1000  has an open top through which block-forming material (e.g., concrete) may be introduced into the first, second, and third mold cavities, and an open bottom through which formed small, medium, and large blocks in an uncured state may be removed, or stripped, from the mold. 
   As shown, the mold in the illustrated embodiment is configured such that the end wall  1002  forms the first, or larger, face  18  of the large block  10 , and the end wall  1004  forms the second, or smaller, face  120  of the medium block  100  and the second, or larger, face  218  of the small block  200 . However, the mold also can be configured to mold the blocks in positions that are reversed from that shown in  FIG. 20  such that the second face  20  of the large block is formed by the end wall  1002 , and the first face  118  of the medium block and the second face  220  of the small block are formed by the end wall  1004 . 
   In the illustrated embodiment, the interior surfaces  1032  and  1034  of the end walls  1002 ,  1004  and the surfaces  1036  and  1038  of the plates  1012 ,  1014  are configured to texture adjacent surfaces of the small, medium and large blocks as they are removed from their respective mold cavities, as described in greater detail below.  FIGS. 21-23  illustrate in greater detail the end wall  1002  of the mold  1000  shown in  FIG. 20 . The end wall  1004  and the plates  1012 ,  1014  have a construction that is similar to that of the end wall  1002 . Thus, the following description, which proceeds in reference to the end wall  1002 , is also applicable to the end wall  1004  and the plates  1012 ,  1014 . 
   As best shown in  FIG. 21 , the interior surface  1032  of the end wall  1002  is formed with a plurality of abutting block-texturing members, or projections,  1056  that extend into the first mold cavity  1026  and contact an adjacent surface of an uncured, large block. The interior surfaces  1034 ,  1036 ,  1038  also are formed with projections  1056  that contact adjacent block surfaces of uncured blocks in the mold cavities. As the mold  1000  is moved vertically with respect to the small, medium, and large blocks for removing them from their respective mold cavities, as indicated by arrow A in  FIG. 21 , the projections  1056  produce a “scraping,” or “tearing,” action on the respective adjacent block surfaces, thereby creating an irregularly roughened surface for those sides of the blocks. A horizontally extending screed  1086  ( FIG. 22 ) can be provided at the bottom edge of the end walls  1002 ,  1004  and the plates  1012 ,  1014 . Each screed desirably extends horizontally a distance approximately equal to the height of the projections  1056 . The screed functions to flatten or smooth out any high points on the adjacent block surface as the mold moves vertically relative to the blocks. 
   As shown in  FIGS. 21-23 , the projections  1056  desirably taper as they extend outwardly from the wall  1002 . In the illustrated embodiment, for example, each projection  1056  is generally “frust-pyramidal” in shape, that is, each projection  1056  has a square-shaped base  1066  at the surface  1032  of the wall, a flattened, square-shaped end surface or crest  1068  spaced from the base  1066 , and four flat side surfaces  1058 ,  1060 ,  1062  and  1064  that converge as they extend from the base  1066  to the end surface  1068 . However, it is contemplated that other tapered or non-tapered shapes may be used for the projections  1056 . For example, the projections may be pyramidal, conical, frust-conical, rectangular, square, cylindrical, or any of other various shapes. 
   Desirably, the projections  1056  are distributed uniformly throughout the surface area of the interior surface  1032 , except at side portions  1040  and  1042  that abut against the mold inserts  1018 ,  1020  ( FIG. 20 ). As best shown in  FIG. 21 , the projections  1056  desirably are arranged side-by-side in diagonal rows (with the base  1066  of each projection sharing a common side with an adjacent projection) extending across the surface  1032  without spacing between projections or between adjacent rows of projections. In the illustrated embodiment, the diagonal rows extend at 45 degree angles with respect to the edges of the wall. However, in other embodiments (such as shown in  FIG. 26 , described below), the projections can be arranged in rows that form angles that are less than or greater than 45 degrees with respect to the edges. Arranging the projections in diagonally extending rows minimizes the retention of block-forming material on the end wall  1002  and maximizes contact between the projections and the adjacent block surface to achieve a consistent texture across the surface. 
   In other embodiments, the rows of projections  1056  may extend horizontally across the first surface so as to form a “checkerboard” pattern of projections. In addition, in other embodiments, the projections  1056  may be spaced apart in the direction of the rows of projections. In still other embodiments, the rows of projections may be spaced from each other. 
   As shown in  FIG. 21  and except for those projections bordering side portions  1040 ,  1042  of the interior surface  1032 , the base  1066  of each projection  1056  adjoins the base  1066  of an adjacent projection to minimize spacing between the crests  1068  of adjacent projections. The side surfaces  1058 ,  1060  of each projection  1056  face in a generally upward direction and the side surfaces  1062 ,  1064  of each projection  1056  face in a generally downward direction. Thus, it can be seen that the side surfaces  1058 ,  1060 , along with the end surface or crest  1068 , of each projection  1056  produce the scraping action against the adjacent surface of a large block in the first mold cavity as the mold  1000  is moved vertically with respect to the block in the direction of arrow A. 
   In the illustrated embodiment, the side surfaces  1058 ,  1060  of the projections  1056  have slopes that are less than the slopes of the side surfaces  1062 ,  1064 . This minimizes the likelihood of fill material being retained in the spaces between adjacent projections as the block is being removed from the mold cavity. In other embodiments, the side surfaces of each projection can be oriented at the same angle with respect to the interior surface  1032 . 
   The wall  1002  and the projections  1056  can have a unitary, monolithic construction, and may be formed by machining the projections  1056  into one surface of a piece of material used to form the wall. The end wall  1004  and plates  1012 ,  1014  can be made in a similar manner. In one specific and exemplary implementation, the projections  1056  are machined in a ½ inch thick piece of material (e.g., steel) to a depth of about ¼ inch. The width of each projection is about 0.87 inch at their respective bases  1066  and about 0.19 inch at their respective end surfaces  1068 . 
   In other embodiments, the projections may be separately formed and then coupled or otherwise mounted to the mold wall, such as by welding or with conventional releasable fasteners (e.g., bolts). If releasable fasteners are used, projections that are worn-out can be removed and replaced with new projections. 
   In still other embodiments, the end walls  1002 ,  1004  can be used as “inserts” that are attached to the flat end walls of an existing mold. Similarly, the plates  1012 ,  1014  can be used as inserts that are attached to an existing divider wall of a mold. 
   In one specific and exemplary implementation, the mold  1000  has a length L ( FIG. 20 ) of about 24 inches extending between the interior surfaces  1032 ,  1034  of the end walls, and a width W of about 18 inches extending between the interior surfaces of the side walls  1006 ,  1008 . These dimensions allow the mold  1000  to be used with a standard size block-forming machine, such as commonly used to form three, 8 inch×8 inch×16 inch concrete building blocks. Notably, the small, medium, and large blocks formed from the mold cavities  1026 ,  1028 ,  1030  have a minimum depth (the dimension extending between the first and second faces of a block) of at least 11.5 inches, and more preferably, at least 12 inches, and hence are suitable for constructing walls up to at least 4 feet in height without geogrid. In contrast, conventional molding techniques cannot be used to form blocks of this size in a standard size mold because either sacrificial portions must be molded to the blocks or additional concrete must be retained in the mold to form the roughened surfaces of each block. Unlike conventional techniques, the mold  1000  is used to form roughened surfaces on two opposing faces of each block without retaining concrete in the mold and without forming any sacrificial portions on the blocks. The height of the mold  1000  can vary and depends on the final desired height of the blocks. 
   The mold  1000  may be adapted for use with any conventional block-forming machine, such as those available from Columbia Machine (Vancouver, Wash.), Masa-USA, LLC (Green Bay, Wis.), Knauer Engineering (Germany), Besser, Inc. (Alpina, Mich.), Tiger Machine (Japan), or Hess Machinery (Ontario, Canada), to name a few. 
   Referring to  FIG. 24 , a method for using the mold  1000  for forming a small, medium, and large block, according to one embodiment, will now be described. As shown, the mold  1000  can be supported on a pallet  1080  or other support. To further minimize the retention of concrete in the mold, a concrete release agent can be applied to the interior surfaces  1032 ,  1034 ,  1036 ,  1038 . 
   The mold  1000  and the pallet  1080  can be moved into place under a first pusher plate (commonly known as the mold head), or stripper shoe,  1082 , a second pusher plate, or stripper shoe,  1084 , and a third pusher plate, or stripper shoe (not shown), such as by way of a conveyor (not shown). Forms (not shown) for forming the pin holes in each block can be inserted into the mold cavities  1026 ,  1028 ,  1030 . The forms can be supported by bars (not shown) that extend transversely across the open top of the mold  1000  and are supported by the side walls  1006 ,  1008  of the mold, as known in the art. 
   The first pusher plate  1082  is shaped so as to be able to fit slidably within the first mold cavity  1026 , the second pusher plate  1084  is shaped so as to be able to fit slidably within the second mold cavity  1028 , and the third pusher plate (not shown) is shaped so as to be able to fit slidably within the third mold cavity  1030 . The pusher plates may be coupled to any suitable mechanism for moving the pusher plates between raised and lowered positions and for pressing the pusher plates against the top surface of the blocks in the mold cavities. For example, the pusher plates may be coupled to a hydraulic ram, as generally known in the art. 
   The mold cavities  1026 ,  1028 ,  1030  are loaded with a flowable, composite cementitious fill material through the open top of the mold. Composite fill material generally comprises, for example, aggregate material (e.g., gravel or stone chippings), sand, mortar, cement, and water, as generally known in the art. The fill material also may comprise other ingredients, such as pigments, plasticizers, and other fill materials, depending upon the particular application. 
   The mold  1000 , or the pallet  1080 , or a combination of both, may be vibrated for a suitable period of time to assist in the loading of the mold with fill material. The pusher plates are then lowered into the mold cavities  1026 ,  1028 ,  1030 , against the top of the mass of fill material in each cavity. The pusher plates desirably are sized so as to provide a slight clearance with the projections  1056  when lowered into the mold cavities. Additional vibration, together with the pressure exerted by the pusher plates acts to densify the fill material and form the final shape of the blocks. 
   After a large block  10 , a medium block  100 , and a small block  200  are formed in the mold cavities, the blocks, in an uncured state, are removed from the mold such as by raising the mold  1000  (as indicated by arrow A in  FIG. 25 ), while maintaining the vertical position of the pusher plates and the pallet  1080  so that the blocks are pushed through the open bottom of the mold  1000 . As the mold moves upwardly relative to the uncured blocks, the projections  1056  pass upwardly through the uncured concrete as the concrete flows around the projections. 
   Alternatively, the blocks can be pushed through the mold  1000  by moving the pusher plates through the respective mold cavities, while simultaneously lowering the pallet and maintaining the vertical position of the mold  1000 . In either case, the action of stripping the blocks  10 ,  100 ,  200  from the mold  1000  creates a roughened surface texture on the first and second faces of each block. Since the mold is not configured to retain fill material for the purpose of creating the roughened surfaces of the block, unlike some prior art devices, the mold  1000  does not require frequent stoppages in production to clear material from the walls of the mold. 
   Additionally, because the projections  1056  do not retain fill material as the blocks are stripped from the mold, the blocks maintain their dimensional tolerances. Thus, the roughened surfaces of each block (e.g., the first and second faces  18 ,  20  of the large block  10 ) will be substantially perpendicular to the block upper and lower surface, and each block will have a substantially constant cross-sectional profile from top to bottom. 
   The mold filling time, the vibration times and the amount of pressure exerted by the pusher plates are determined by the particular block-forming machine being used, and the particular application. After the small, medium, and large blocks are removed from the mold, they may be transported to a suitable curing station, where they can be cured using any suitable curing technique, such as, air curing, autoclaving, steam curing, or mist curing. The foregoing cycle can then be repeated to form another small, medium, and large block using the mold  1000 . 
   An advantage of the foregoing method is that it minimizes waste material in at least two ways. First, the blocks do not have to be formed with any sacrificial portions (which typically are about 2 inches thick) that are subsequently removed to form split faces on the blocks. Second, the interior mold surfaces having projections  1056  are designed to minimize the retention of block-forming material in the mold as the uncured blocks are removed from the mold. Thus, the amount of waste material is significantly reduced compared to conventional techniques that are used to form roughened surfaces on blocks. 
     FIG. 26  illustrates a mold wall  1100 , according to another embodiment, for creating a roughened surface texture on a block surface. The wall  1100  can be used, for example, in lieu of the end wall  1002  in the mold  1000  ( FIGS. 20 ,  21 ). The wall  1100  is formed with a plurality of projections  1156  arranged in rows extending diagonally across the surface of the wall. The wall  1100  has the same construction as the wall  1002  ( FIGS. 20-23 ), except that the diagonal rows of projections  1156  extend at angles less than or greater than 45 degrees with respect to the edges of the wall. As shown, the rows extending upwardly left to right, such as row  1106 , form an angle  1102  with respect to the upper edge of the wall, and the rows extending upwardly right to left, such as row  1108 , form an angle  1104  with respect the upper edge of the wall. Consequently, the crests  1168  of the projections  1156 , unlike the projections  1053  of  FIG. 21 , are not vertically aligned from the upper edge to the lower edge of the wall. Advantageously, this provides for a more consistent surface texture on the face of a block. The end wall  1004  and the plates  1012  and  1014  ( FIG. 20 ) also can be provided with projections  1156  that are arranged in the manner shown in  FIG. 26 . 
   In particular embodiments, for example, the rows extending upwardly left to right, such as row  1106 , are oriented at an angle of about 60 degrees with respect to the wall upper edge, and the rows extending upwardly right to left, such as row  1108 , form an angle of about 30 degrees with respect the wall upper edge. 
   The invention has been described with respect to particular embodiments and modes of action for illustrative purposes only. The present invention may be subject to many modifications and changes without departing from the spirit or essential characteristics thereof. I therefore claim as our invention all such modifications as come within the scope of the following claims.