Concrete Block And Method Of Making Same

Molds and processes that permit high-speed, mass production of retaining wall blocks having patterned or other processed front faces, as well as retaining wall blocks formed by such processes. The invention permits the front face of the block to be impressed with a pattern or otherwise directly processed, to allow the formation of pre-determined concrete brick machine front faces, while at the same time facilitating high-speed, high-volume production of blocks.

A mirror image of the desired pattern can be created on a stripper shoe by selecting a desired three-dimensional surface from a naturally occurring or man made object and digitally scanning the selected three-dimensional pattern to create scanned data. The scanned data can then be used to machine a face of the stripper shoe that is the mirror image of the selected pattern.

A method of making a concrete block having a three dimensional patterned face, comprising the steps of: selecting a three-dimensional pattern of one or more existingobjects; digitally scanning the selected three-dimensional pattern to create scanned data in XYZ coordinates that is representative of the selected three-dimensional pattern; creating from the scanned data in the XYZ coordinates a digital data set thatis representative of a desired three dimensional patterned face of the concrete block based on the scarmed data of the three-dimensional pattern; using the digital data set to create a mold surface with a three-dimensional pattern that is the mirrorimage of the desired three dimensional patterned concrete block face, the three-dimensional pattern on the mold surface having a maximum relief of at least about 0.5 inches; providing a mold having a plurality of side walls defining a mold cavity, themold including the mold surface with the mirror image of the desired three-dimensional pattern concrete block face; introducing dry cast concrete into the mold cavity; compacting the dry cast concrete to form a pre-cured concrete block, wherein duringcompaction, the desired three-dimensional patterned face is imparted to the pre-cured concrete block by the mold surface with the mirror image of the desired three dimensional patterned concrete block face; discharging the pre-cured concrete block fromthe mold cavity; and curing the pre-cured concrete block.

The invention relates generally to concrete blocks and the manufacture thereof. More specifically, the invention relates to concrete blocks suitable for use in landscaping applications, such as retaining walls, and manufacturing processes usefulin the production of such blocks.

Modern, high speed, automated concrete block plants and concrete paver plants make use of molds that are open at the top and bottom. These molds are mounted in machines which cyclically station a pallet below the mold to close the bottom of themold, deliver dry cast concrete into the mold through the open top of the mold, densify and compact the concrete by a combination of vibration and pressure, and strip the mold by a relative vertical movement of the mold and the pallet.

Due to the nature of such plants and the equipment used to perform this process, it is difficult to impart a natural appearance to the face of a concrete block, particularly if the block needs to include other features, such as converging sidewalls, and an integral locator and shear flange(s) formed on the top and/or bottom face of the block. U.S. Pat. No. 5,827,015, which is incorporated herein by reference, discloses such a concrete block suitable for use as a retaining wall block, andthe common method for producing such a block in a high speed, automated concrete block plant.

There is demand for a pre-formed concrete unit, particularly a retaining wall block with converging side walls and/or an integral locator and shear flange formed on the top and/or bottom face, and having a more natural appearing face than isachievable by the splitting process described in U.S. Pat. No. 5,827,015, or by the splitting process described in U.S. Pat. No. 6,321,740, which is also incorporated herein by reference. In particular, there is a demand for processes and toolingthat will create such blocks with such faces in high-speed, automated fashion on the type of equipment commonly available in a concrete block or concrete paver plant.

The invention relates to molds and processes that permit high speed, mass production of concrete units, and, in particular, retaining wall blocks. These molds and processes can be used to create relatively simple decorative front faces on suchblocks, similar to the split faces described in U.S. Pat. No. 5,827,015. These molds and processes can also be used to create more complex front faces on such blocks, similar to the split and distressed faces produced by conventional tumbling orhammermill processing, or by the process described in U.S. Pat. No. 6,321,740. These molds and processes can also be used to create unique blocks that have heretofore not been available: retaining wall blocks with converging side walls and/or integrallocator and shear flanges and with front faces with significantly more complex faces, including faces with significant detail and relief not heretofore available in dry cast concrete block technology.

In a preferred embodiment, the resulting blocks have patterned front faces that simulate natural stone, as well as upper and lower faces, a rear face, opposed converging side faces, and a flange extending below the lower face. Blocks having thisconstruction, when stacked in multiple courses with other similarly constructed retaining wall blocks, permits construction of serpentine or curved retaining walls that appear to have been constructed with naturally-occurring, rather than man-made,materials.

One aspect of this invention is that a mold made in accordance with the invention is arranged so that the portion of the block that will be the front face when the block is laid is facing the open top of the mold cavity during the moldingprocess. This orientation permits the front face of the block to be formed by the action of a patterned pressure plate ("stripper shoe") in a high-speed, concrete block or paver plant. The stripper shoe can be provided with a very simple pattern, amoderately complex pattern, or a highly detailed, three-dimensional pattern with significant relief, simulating naturally occurring stone. Molding the block in this orientation also makes the block face readily accessible for other processing to affectthe appearance of the face, including the application of specially-selected aggregate and/or color pigments to the face.

Another aspect of this invention is that a side wall of the mold has an undercut portion adjacent the open bottom of the mold cavity. This undercut portion cooperates with the pallet that is positioned under the mold to form a subcavity of themold. In a preferred embodiment, this subcavity forms the locator and shear flange on the surface of the block that will be the bottom of the block machine as laid.