Not applicable.
Not applicable.
The invention relates to a process casting concrete wall blocks having a central passage for securing a geogrid fabric to the wall block, and to wall blocks cast according to the process.
Geogrid systems are commonly used for stabilizing retain walls. In one such system, a retaining wall is formed from stacked large concrete blocks. Passages or openings are formed to extend vertically through each block. In constructing a retaining wall, a first tier of blocks is set in place. Geogrid webs are positioned to stabilize the blocks in this tier. Each web extends from behind the blocks and upwardly through a vertical opening in a block. Backfill is then placed over the web and compacted, and the web is then positioned to extend from the top of the block over the compacted backfill. After each block in the tier is secured with one or more webs and backfill is added behind the tier, a second tier of blocks may be stacked on the first tier of blocks. The blocks are then secured with geogrid webs and backfill is added behind the second tier of blocks. This process is continued until the retaining wall extends to a desired height and width. This retaining wall system is shown, for example, in U.S. Pat. No. 6,565,289 wherein two geogrid webs anchor each wall block.
The invention is directed to a method of casting concrete retaining wall blocks and to the cast blocks for use with a geogrid system which stabilizes a wall constructed with the blocks. Mold inserts are used to form a passage between top and bottom surfaces of the block, a recess in the block top between the top of the passage and the rear of the block and a recess in the bottom of the block between the bottom of the passage and the rear of the block. When constructing a retaining wall with the blocks, a web of geogrid fabric is passed from the rear of the block through one of the recesses, through the passage and back through the other recess to the rear of the block. The geogrid fabric is anchored in backfill behind the retaining wall. According to the invention, the recesses and the passage are formed by a plurality of mold inserts to provide smooth contact surfaces for the geogrid fabric. The recesses and passage are designed so that corners are rounded and so that any concrete flashing formed between abutting mold inserts is not contacted by the geogrid fabric.
Various objects and advantages of the invention will become apparent from the following detailed description of the invention and the accompanying drawings.
An exemplary concrete wall block 10 is illustrated in
In the illustrated embodiment of the block 10, two knobs 17 and 18 project from the block top 15. The knobs 17 and 18 are spaced apart and are equally spaced from the block face 11. Two complimentary recesses 19 are formed in the block bottom 16. When a number of blocks 10 are stacked, the recesses 19 on an upper block in the stack receive the knobs 17 and 18 from two adjacent lower blocks for securing the blocks together and preventing movement of the blocks. In an alternate embodiment, the recesses 19 may be replaced with a groove extending the width of the block bottom 16 which is shaped to receive the knobs from adjacent lower blocks in the stack. The groove facilitates angling adjacent blocks in each tier for forming a bend or a curve in a retaining wall.
A passage 20 extends a generally vertical direction through the center of the block 10 between the knobs 17 and 18. A recess 21 is formed in the block top 15 to connect the passage 20 to the block back 12, and a recess 22 is formed in the block bottom 16 to connect the passage 20 to the block back 12. The recess 21, the passage 20 and the recess 22 sized to receive a geogrid strap or web for securing the block 10 to backfill behind a retaining wall which includes the block 10.
In
In manufacturing the block 10, the recesses 21 and 22 and the passage 20 are formed by inserts which are positioned in the form in which the block 10 is cast. The inserts are withdrawn from the block after the concrete has cured. In order to form the desired shapes of the recesses 21 and 22 and the passage 20, a plurality of inserts are used. When the concrete block is cast, a limited amount of cement may flow into seams between the abutting mold inserts. When this cement hardens, it can form rough flashing in the recesses and the passage. If the geogrid fabric comes into contact with the flashing, it can cut or weaken the geogrid, and possibly adversely affect the stability of the retaining wall. According to the invention, the recesses 21 and 22 and the passage 20 are designed so that the geogrid web contacts only smooth surfaces and cannot come into contact with sharp corner or with any flashing produced during the block casting process.
The passage 20 and the recesses 21 and 21 have a width greater than the width of the geogrid web. When looking in the direction of the cross section shown in
Various modifications and changes may be made to the above described process and block without departing from the scope of the following claims.
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