Molds for producing concrete blocks with roughened surfaces; blocks made therefrom; and methods of use

A mold for making dry cast concrete blocks includes a pair of vertical shoulder forming sections, one along each of the opposite sides of the mold to form vertical front shoulders of a block. Each shoulder forming section has a shoulder roughening arrangement to result in molded, roughened shoulders of the block. Methods of making such blocks and the resulting block are included.

TECHNICAL FIELD

This disclosure concerns molds for concrete products. In particular, this disclosure concerns molds for making dry cast concrete blocks, in which surfaces of the resulting block are roughened.

BACKGROUND

Concrete units are available in a wide range of sizes and shapes, and are used for a variety of applications ranging from concrete blocks and bricks for building construction to landscaping units, including segmental retaining wall blocks (the latter are sometimes called “SRW” blocks).

Depending on the intended end-use application of the concrete units being produced, the surface appearance of the units may be important, and the marketplace has come to expect various decorative or cosmetic surface finishes for many units. Such surface finishes include those commonly described as broken or split, striped, striated, simulated broken, and smooth (alone or in combination with one of the other surface finishes). One such surface finish is a texture that resembles the appearance of a “split” rock. A “split” surface finish on a concrete unit may be achieved by mechanically splitting away a portion of a face of the masonry unit. This is typically achieved with a mechanical splitting blade similar to a guillotine, and the splitting is performed on the units after they have been cured or hardened. To avoid waste, this is often done by first forming the units as “Siamese” twins and then splitting them apart. The resulting fracture surface on the front face of both blocks is generally thought to be aesthetically pleasing and decorative.

The mechanical splitting of units is an added cost of processing. This cost provides an incentive to develop new methods of roughening the surface of concrete units to create a desirable surface finish without the need to mechanically split the masonry units. Although some approaches have involved processing steps to be performed on the green or uncured masonry units immediately after they are discharged from the mold, one common approach has been to modify the mold in some fashion so that a roughened surface is produced on the concrete units as they are ejected from the mold (i.e. the units are roughened in the mold cavity).

At times, it is desired to produce a more modest or fine roughening of a masonry unit than is typically produced when mechanically splitting a block. Unfortunately, the molds used to produce pronounced roughening are often unsuited for the more modest roughening. If they are scaled down to produce more moderate roughening, they often have more delicate features that lack the desired strength and wearability. Modest roughening of one or more surfaces of a concrete unit such as a brick or block is useful not only as the only surface finish, but it is useful in combination with mechanical splitting where the modest roughening can be performed on surfaces of the block which are not to be mechanically split, but which may be visible to the observer when the products are used, for example, to create a retaining wall. By roughening the surfaces immediately adjacent to the mechanically split surface(s), light striking the adjacent surfaces is scattered and the reflections associated with smooth reflective surfaces are avoided.

SUMMARY

This disclosure relates to an improved mold that is well suited for making concrete products having roughened vertical front shoulders.

In accordance with principles of this disclosure, a mold for making dry cast concrete blocks includes opposed side walls, opposed end walls, and an open top and bottom. The mold includes a pair of vertical shoulder forming sections, one along each of the side walls across the mold from each other in position to form the vertical front shoulders of a dry cast concrete block. Each shoulder forming section is concave about a vertical axis to form a rounded front vertical shoulder on a block. Each shoulder forming section has a recess starting adjacent the lower edge of the mold and extending upward between about 25% and about 50% of the side wall height of the side wall of the mold. One or more ribs is formed in each of the recesses. Each rib extends in a direction across the width of the recess, and the one or more ribs together extend across at least a majority of the width of the recess.

In another aspect, a presplit molded dry cast concrete block pair is provided. The block pair includes a first block form having a rear surface and first and second opposite side walls extending from the rear surface. The block pair further includes a second block form having a rear surface and first and second opposite side walls extending from the rear surface in a direct toward the first block form. A top surface is between the first rear surface and the second rear surface. A bottom surface, opposite of the top surface, is between the first rear surface and the second rear surface. First and second rounded, roughened shoulders are provided defining a gap therebetween. The first shoulder is at the end of the first block form first side wall, and the second shoulder is at the end of the second block form first side wall. There are further third and fourth rounded, roughened shoulders defining a gap therebetween. The third shoulder is at the end of the first block form second side wall, and the fourth shoulder is at the end of the second block form second side wall.

In another aspect, a method of molding a dry cast concrete block is provided. The method includes providing a mold having a cavity defined by opposed side walls, opposed end walls, an open top, an open bottom, and a pair of vertical shoulder forming sections, one along each of the side walls across the mold from each other. Each shoulder forming section is concave about a vertical axis to form a rounded front vertical shoulder on a block. Each shoulder forming section has a recess starting adjacent the lower edge of the mold and extending upward between about 25% and about 50% of the height of the mold. One or more ribs is formed in each of the recesses, each rib extending in a direction across the width of the recess, the one or more ribs together extending across at least a majority of the width of the recess. The mold has a pallet underneath to temporarily close the open bottom. The method further includes depositing dry cast concrete in the mold cavity. Next, there is a step of compacting the concrete in the mold cavity by introducing a stripper shoe through the open top of the mold box including forming vertical front shoulders having roughened surfaces by contact between the concrete and the ribs in the recesses of the shoulder forming sections. Next, there is a step of discharging an uncured concrete block through the open bottom of the mold box onto the pallet.

DETAILED DESCRIPTION

A. Overview of Example Molded Block and Block Pair, FIGS.1-3

The present disclosure provides a mold for making a block, the resulting block, and methods of use. The resulting block includes a roughened front face and roughened rounded front shoulders, to provide the appearance of a natural rock or stone surface. The mold used to make the block includes shoulder forming sections with an arrangement for providing the roughness on the vertical shoulders of the resulting molded block.

Referring now toFIG. 1, one example embodiment of a dry cast concrete block according to principles of this disclosure is shown generally at15. In the example shown, the block15includes a block body20including a front surface22and a back surface24, which are substantially parallel to each other. The front22and back24surfaces are separated by a distance comprising the depth of the block. The block has an upper surface26and a lower surface28separated by a distance comprising the height of the block15. InFIG. 1, the block15is depicted upside-down from the orientation it has in use. In use, the lower surface28is the base surface.

The block has a first30and second31side wall separated by a distance comprising the width of the block. The side walls30,31join the block upper and lower surfaces26,28. At the intersection between the front surface22and first side wall30is a first shoulder32. At the intersection between the front surface22and the second side wall31is a second shoulder33. The first and second shoulders32,33extend vertically between the lower surface28and upper surface26. In one embodiment, the radius of the first shoulder32and second shoulder33is the same and ranges between 1.00-1.10 inch, preferably about 1.099 inch. In the embodiment shown, the first shoulder32extends between the point34where the front surface22stops and the point35where the first side wall30stops. Similarly, the second shoulder33extends between point36where the front surface22stops and point37where the second side wall31stops.

In the embodiment shown, the first side wall30and second side wall31are angled and converge as they extend from the front surface22to the back surface24. These converging side walls30,31result in blocks15that can be manipulated to form curved walls.

The block15has a flange40spanning the width of the block back surface24and extending from the block back surface24past the height of the block. Generally, the flange40comprises a set back surface42and a locking surface44. The set back surface42extends from the lower edge of the flange40in a plane parallel to the block upper26and lower28surfaces towards the block front surface22. The locking surface44extends from the plane of the block lower surface28to the set back surface42.

The block body20provides weight and physical structure to the system in which the block15is used. Landscaping elements, such as retaining walls, often must be constructed of units that not only provide a structural impediment to resist the natural flow of soil, but must also provide the shear weight to withstand these forces. Moreover, the body of the block15functions to provide the supporting surfaces that may be used to provide an aesthetically pleasing pattern such as that found on the front surface22of the block15. The body20of the block15may also provide a substrate for holding elements that help form an interlocking matrix with other blocks when used in a structure such as a wall. In particular, the block15includes flange40, which assists in the interlocking function of the block15.

The block front surface22preferably has a roughened appearance to enhance the aesthetic appeal of the block. The roughened appearance is preferably formed by splitting two face-to-face concrete blocks molded into a block pair. One example of a molded block pair is shown inFIGS. 2 and 3.

Referring now toFIGS. 2 and 3, a molded block pair is shown generally at50. The molded block pair50depicted inFIGS. 2 and 3is pre-split. That is, the molded block pair50, in the pre-split form as shown inFIGS. 2 and 3, is an intermediate form before appearing as block15with the roughened front surface22. Generally, the molded block pair50is split along a split line52(FIG. 2), which bisects the block pair50. The splitting can be done by using a conventional block splitter having a splitting blade, and may include splitters such as those described in U.S. Pat. No. 6,874,494, incorporated by reference herein. After splitting the molded block pair50, the result is two individual blocks15, each block having a roughened front surface22, resulting from the split. In accordance with principles of this disclosure, the block15, after splitting, also has roughened first and second shoulders32,33.

InFIG. 2, the molded block pair50includes first and second block forms54,56that are molded as a single, continuous piece with the split line52therebetween. The first block form54has a rear surface58and first and second opposite side walls60,62extending from the rear surface58. The second block form56also has a rear surface64and first and second opposite side walls66,68extending from the second form rear surface64and in a direction toward the first block form54. The molded block pair50further includes a top surface70(FIG. 3) extending between the first block form rear surface58and the second block form rear surface64. A bottom surface72, opposite of the top surface70, extends between the first block form rear surface58and the second block form rear surface64. The block pair50ofFIGS. 2 and 3is depicted upside-down, with the bottom surface72facing up. After splitting, in normal use the two split blocks15will rest on bottom surface72.

InFIGS. 2 and 3, it can also be seen how in this embodiment, the first block form54has a flange74extending along the rear surface58and projecting above the bottom surface72. Similarly, the second block form has a flange76extending along the rear surface64and projecting above the bottom surface72.

The molded block pair50further includes first and second shoulders78,79defining a gap80therebetween. The first and second shoulders78,79are rounded and roughened. InFIG. 2, the first shoulder78is adjacent the split line52and at the end of the first block form first side wall60. The second shoulder79is adjacent to the split line52and is at the end of the second block form first side wall66. As used herein, the term “gap” refers to the distance between the outermost radius of each of the first and second shoulders78,79. The split line52bisects the gap80.

Analogously, at the opposite side of the molded block pair50, are a third and fourth shoulders82,83defining a gap84therebetween. The third shoulder82and the fourth should83are rounded and roughened. The third shoulder82is at the end of the first block form second side wall62, while the fourth shoulder83is at the end of the second block form second side wall68. Each of the third and fourth shoulders82,83are adjacent to the split line52, with the first shoulder78and third shoulder82being on the same side of the split line52as the rest of the first block form54. The second shoulder79and fourth shoulder83are on the same side of the split line52as the second block form56. The gap84is bisected by the split line82.

As mentioned above, the shoulders78,79,82,83are roughened. By the term “roughened”, it is meant that the surface texture is 3-dimensional and has a craggy appearance having a relief of between about 0.09 inch and about 0.125 inch.

As can also be seen inFIG. 2, in the preferred embodiment, the first and second side walls60,62converge as they extend from the second block form56and split line52toward the rear surface58. Similarly, the first and second side walls66,68converge as they extend from the first block form54and split line52toward the rear surface64. Stated another way, the first block form first and second side walls60,62diverge as they extend from the rear surface58toward the second block form56, and the second block form first and second side walls66,68diverge as they extend from the second block form rear surface64toward the first block form54. As described above with respect to block15, the converging side walls results in blocks15that can form curved or serpentine walls.

InFIGS. 1 and 2, it is also apparent that, in the preferred embodiment, there are core openings86. Specifically, the first block form54includes first and second core openings88,89, while the second block form56includes second block form first and second core openings91,92. The core openings88,89,91,92result in blocks15having less mass, than if molded without the core openings. This results in blocks15that are easier to manipulate since the weight is less then a block that does not have core openings.

Referring now toFIGS. 4 and 5, an embodiment of a mold100(FIG. 5) used for making dry cast concrete blocks, such as block15, is depicted.FIG. 4shows an assembled mold box102resting on a pallet104. InFIG. 5, the mold box102is shown in an exploded view, with additional mold parts as part of the overall mold100, described further below.

Referring now toFIG. 4, the mold box102includes first and second opposed side walls106,107. The mold box102further includes first and second opposed end walls108,109. Together, the side walls106,107and end walls108,109define a mold cavity110. The mold cavity110has an open top112and an open bottom114. InFIG. 4, the open bottom114is closed by the pallet104.

The mold box102further includes a pair of vertical shoulder forming sections, in the form of a first vertical shoulder forming section116and a second vertical shoulder forming section117. The vertical shoulder forming sections116,117are mirror-images of each other. There is one vertical shoulder forming section116,117along each of the side walls106,107across the mold box102from each other in position to form the vertical front shoulders, such as the first shoulder32and second shoulder33, of the dry cast concrete block15.

The first and second shoulder forming sections116,117are constructed and arranged to result in vertical shoulders on a molded block, such as shoulders32,33on block15, in which the shoulders are roughened.

Preferably, each shoulder forming section116,117is concave about a vertical axis, which is orthogonal to the pallet104. Certain preferred shoulder forming sections are described more fully below with respect toFIGS. 7-11. The first and second shoulder forming sections116,117are part of the overall mold100, shown in exploded view inFIG. 5.

The mold100shown inFIG. 5is a type of mold that would be used for making the molded block pair50ofFIGS. 2 and 3. In other embodiments, the mold100can be the type of mold that would result in a single block, rather than a block pair, and the single block would not then be subject to splitting. The single block, however, may be subject to other types of roughening after de-molding and curing, such as breaking off an end piece to form a roughened front face.

InFIG. 5, the mold cavity110is defined by first and second outside division plates122,123. In the assembled mold box102ofFIG. 4, these first and second division plates122,123correspond to the first and second end walls108,109. The mold cavity110is further defined by a plurality of wear plates124,125,126,127. Between the wear plates124and125is a center wear plate130. Between the wear plates126and127is another center wear plate131. Together, the wear plates124,125, and center wear plate130form the first side wall106of the mold box102ofFIG. 4. Similarly, the wear plates126,127and center wear plate131form the second side wall107of the mold box102. Therefore, inFIG. 5, the mold cavity110is defined by first and second division plates122,123; wear plates124,125,126,127; and center wear plates130,131. The center wear plates130,131form the first and second shoulder forming sections116,117. This is described further below in section C.

As can be seen inFIG. 5, the wear plates124-127are shaped such that they diverge from each other as they extend from the respective division plate122,123in a direction toward the respective center wear plate130,131.

The outside division plates122,123, as well as the wear plates124-127and center wear plates130,131are secured to first and second side bar assemblies134,135, which extend the length of the mold100. Specifically, in the embodiment ofFIG. 5, the first side bar assembly134is secured to the wear plate124,125and center wear plate130, while the second side bar assembly135is secured to the wear plates126,127and center wear plate131. A plurality of hold down blocks136are shown, and are useful for connecting the side bar assemblies134,135together.

Above the portions of the mold100forming the mold box102is a mold top plate assembly138. The mold top plate assembly138cooperates with the core bar assembly140, two of which are shown in theFIG. 5embodiment. Each of the core bar assemblies140helps to form core openings88,89,91,92. There is a cut off blade142, which is used for striking off the concrete mixture of the mold100during the molding process.

Above the top plate assembly138and core bar assemblies140is a stripper shoe arrangement144. The stripper shoe arrangement144includes outside stripper shoes146,147and center stripper shoe148. The stripper shoe arrangement144is arranged to slide past the core bar assemblies140and engage the concrete mixture through the open top112(FIG. 4) of the mold box102. The stripper shoe arrangement144presses the concrete mixture out of the mold box102and onto the pallet104(FIG. 4) as part of the molding process.

Above the stripper shoe arrangement144is a top plate150, a pair of outside plunger assemblies151,152, and a center plunger assembly153. The plunger assemblies151-153engage the stripper shoe arrangement144in order to push the stripper shoe arrangement144through the open top112of the mold box104and push out the uncured block pair out of the mold box onto the pallet104(FIG. 4).

Referring now toFIGS. 6-11, an example embodiment of center wear plate130is depicted. The center wear plate131is identical in construction, and description of the center wear plate130also applies to the center wear plate131. The center wear plate130includes at least one, and preferably two shoulder forming sections156,157. When the center wear plate130is assembled in mold box102, the shoulder forming sections156,157will be arranged to form the vertical shoulder forming sections116,117(FIG. 4).

Referring now toFIG. 9, it can be appreciated that each shoulder forming section156,157, is concave about a vertical axis that is orthogonal to the open top and open bottom112,114of the mold box102, when the wear plate130is operably installed therein. The concave shape helps to form rounded shoulders, such as shoulders78,79and82,83on the molded block pair50. After splitting the molded block pair50, rounded shoulders32,33result.

Referring now toFIGS. 6 and 10, the shoulder forming sections156,157each has a recess158,159. Each of the recesses158,159is near a bottom edge162of the wear plate130. When installed in the mold box102, each of the recesses158,159are adjacent the lower edge160(FIG. 4) of the mold box102. In the preferred embodiment depicted, each of the recesses158,159is between 0.25 and 0.35 inch from the bottom edge162of the center wear plate130.

Each recess158,159extends upwardly from the point164adjacent the bottom162(and when assembled in the mold box102, adjacent the lower edge160) to a top point165between about 25% and about 50% of the height of the center wear plate130. When the center wear plate130is assembled in the mold box102, the height of recesses158,159would also be between about 25% and about 50% of the height of the mold box102. The recesses158,159help to form shoulder roughening arrangements166,167, which result in roughened shoulders for a molded block. If the recesses158,159extend much more than 50% of the height of the wear plate130and mold box102, the molded shoulders tend to bulge at the bottom of the block as molded because of too much concrete being pushed through that location. If the recesses158,159are much less than 25% of the height of the wear plate130and mold box102, then the recesses158,159will tend to retain concrete (i.e., they are not self-cleaning), which may result in smooth shoulders unless the recesses158,159are manually cleaned.

InFIGS. 6,10, and11, it can be seen how the shoulder roughening arrangements166,167include projections170extending from a remaining portion of the shoulder forming sections156,157within each recess158,159. When the uncured block is stripped from the mold, the concrete retained in the recesses158,159and the projections170roughen the vertical shoulders78,79and82,83of the molded block pair50.

The projections170can include any structure extending or projecting from the recesses158,159. The projections can include, for example, a plurality of spaced segments or dots. In the example shown inFIGS. 6,10, and11, the projections170are ribs212-215. The ribs212-215are formed in the recesses158,159. The ribs212-215extend in a direction across the width174,175(FIG. 11) of the recesses158,159. Preferably, there are one or more ribs212-215formed in each of the recesses158,159. The one or more ribs212-215together extend across at least a majority of the width174,175of the recesses158,159. In preferred embodiments, the one or more ribs212-215extend across substantially the entire width174,175of the recesses158,159.

In the embodiment depicted inFIGS. 6-11, the center wear plate130includes a plate body180having a top edge181and bottom edge162. The body180includes a molding face184, which faces the mold cavity110and provides a surface against which the concrete mixture engages in order to mold the resulting structure. On a side of the body180opposite of the mold face184is an outside face186. The outside face186forms an outer surface187of the mold box102when assembled with the other mold parts.

The outside face186includes a projecting lug190, projecting away from a remaining portion of the outside face186and away from the molding face184. In the example shown, the lug190is generally rectangular and is spaced from both the top edge181and bottom edge162. The lug190further includes a fastener hole192(FIGS. 7 and 8) for accommodating a fastener in order to connect the center wear plate130with other portions of the mold, such as side bar assembly134,135(FIG. 5).

Extending between the top edge181and the bottom edge162and bridging the molding face184and outside face186are sides194,195. The sides194,195have at least two areas of thickness. The first area of thickness196(FIG. 6) extends from the top edge181to the top point165of the recesses158,159. The first area of thickness196is interrupted by the second area of thickness200(FIG. 6), and then resumes again extending from the point164at the bottom of the recesses158,159to the bottom edge162of the center wear plate130. The second area of thickness200extends between the top point165of the recesses158,159and point164, being the bottom end of the recesses158,159. The first area of thickness196is greater than the second area of thickness200. The difference between the first area of thickness196and second area of thickness200defines the depth of the recesses158,159. In one example, this depth is between 0.10 and 0.12 inch, for example about 0.109 inch.

The molding face184includes the shoulder forming sections156,157side by side or adjacent to each other. The shoulder forming sections156,157meet at a common, middle edge202. In the example shown, the middle edge202generally bisects the center wear plate130, being centered between the sides194,195. The middle edge202extends between the top edge181and bottom edge162. Extending between the middle edge202and each respective side194,195is concave shaped molding surfaces204,205(FIG. 11). Each of the concave molding surfaces204,205have a smooth section208,209(FIG. 11) and roughening sections210,211(FIG. 11). The roughening sections210,211are within the recesses158,159. The roughening section210,211each has a floor surface216,217(FIGS. 6 and 11).

The roughening section210includes the first and second ribs212,213projecting from the floor surface216. The ribs212,213are generally parallel to each other. The first rib212extends from the middle edge202at least partly across the roughening section210, and in the example shown, does not extend to the side194. The second rib213is spaced between the first rib212and the bottom164of the recess158. In the example shown inFIG. 11, the second rib213extends from the side194in a direction toward the middle edge202, and extends, in the embodiment shown, only partially toward the edge202. Each of the first and second ribs212,213has a height of about 0.09 inch, which is the distance between the floor surface216and the outer surface of the ribs212,213. Each of the first and second ribs212,213has a width220(FIG. 11) of about 0.104 inch. Other sizes can be used.

The roughening section211is analogous to the roughening section210. The roughening section211includes the first and second spaced ribs214,215projecting from floor surface217. Preferably, the first and second ribs214,215are generally parallel to each other. The first rib214extends from the middle edge202only partially in a direction toward the side195. The second rib215is spaced between the first rib214and the bottom point164of the recess159. The second rib214extends from the side195only partially in extension to the edge202. The first and second ribs214,215are generally at the same height and width220as the ribs212,213, which is preferably about 0.09 inch from the floor surface217for height and about 0.104 inch for width

In the example depicted inFIGS. 6-11, the first ribs212,214meet along the middle edge202. From the middle edge202, the ribs212,214form a V-shape, with the apex being at the edge202, and each rib212,214extends upwardly as they extend away from the middle edge202.

The second ribs213,215do not meet along the middle edge202, in the example shown. The second ribs213,215extend downwardly as they extend from their respective sides194,195toward the bottom edge162of the center wear plate130.

When the center wear plates130,131are operably assembled within the mold box102, the ribs212,213,214,215extend downwardly toward the bottom or lower edge160of the mold100as it extends from one edge of the recess158,159toward the other edge of the recess158,159. From a review ofFIG. 4, it can be seen that in the preferred embodiment, the height of each recess158,159is about 50% of the height of the mold box102.

The angle of the first ribs212,214and second ribs213,215relative to the middle edge202and sides194,195at least partially contribute to the wear plates130,131being self-cleaning, by forcing the concrete in the recesses158,159to the middle edge202as the block is stripped from the mold box102. In the example shown inFIG. 11, the ribs212-215are at an angle218of about 45° relative to respective sides194,195. Other angles can be used.

When the center wear plates130,131are assembled in the mold box102, the concave molding surfaces204of the center wear plates130,131are located across the mold from each other in position to form the first and third vertical front shoulders78,82(FIG. 2) of molded block pair50, which after splitting, results in front shoulders32,33of block15. Similarly, the concave molding surfaces205of the center wear plates130,131are located across the mold100from each other to form second and fourth shoulders79,83(FIG. 2) of molded block pair50, which after splitting, results in front shoulders32,33of block pair15.

It should be appreciated that in use, the mold100can be shaped to result in only a single block15in which the center wear plate130includes only a single concave mold surface.

The mold parts described herein can be used in methods for making a dry cast concrete block, such as block15.

In one example method, the mold100is provided. Dry cast concrete is deposited in the mold cavity110through the open top112. The concrete in the mold cavity110is compacted by introducing the stripper shoe arrangement144through the open top112. This step includes forming the rounded vertical front shoulders. Next, an uncured concrete block is discharged through the open bottom114of the mold box102and on to the pallet104. This step includes roughening the shoulders by the recesses158,159and ribs212-215as the uncured block is discharged from the mold.

The uncured concrete block discharged can be a single block having roughened first and second shoulders32,33. This single block can then have its front face22roughened through a post-molding technique such as using a hammer mill or a by breaking off a chunk of the mold block to form the front face22. Alternatively, the front face22can be formed within the mold itself.

In preferred embodiments, the step of discharging an uncured concrete block includes discharging a uncured concrete block comprising two face-to-face concrete blocks, such as the molded block pair50. In such a case, there are two adjacent vertical shoulders78,79and82,83midway along each side wall66,68. Each of the vertical shoulders78,79and82,83has roughened surfaces by contact between the concrete and the ribs172in the recesses158,159of the shoulder forming sections116,117of the mold100. This molded block pair50is then cured, and split along the split line52to result in two separate blocks15. Each block15has a pair of vertical shoulders32,33with the front face22therebetween. Each of the shoulders32,33and the front face22is roughened in appearance. In preferred methods, the molded block pair50is split using tooling as described in U.S. Pat. No. 6,874,494, incorporated herein by reference. The tooling in U.S. Pat. No. 6,874,494 has ridges along most of the central portion of the splitter and bullets at the corners of the blocks. The bullets help to break the small shoulder areas that are smooth at the bottom of the blocks as molded, to result in roughened shoulders the entire height of the split block.

The above description includes example principles which may be applied to make many embodiments.