This information in this guide is intended to assist the builder in placing Mechanical Concrete ® as a base for a road or to stabilize a site. It is not a construction specification. When this information is in conflict with an engineer’s specification, the conflict should be resolved before construction begins.
STEP 1: Site Preparation
The site should be prepared to receive the tire-derived-cylinders, TDC, by removing surface materials to the required depth. The Mechanical Concrete ® process, with 8 inches of TDC and 2 inches of stone cover, is a approximately 10 inches thick on average when using standard auto tire-derived-cylinders. The subgrade should be suitable to withstand the anticipated loadings. If clay, sand or other soft materials are the subgrade, a layer of woven separation fabric with an additional layer of grid material should be placed on the subgrade before placing the TDC.
STEP 2: Placing TIRE-DERIVED-CYLINDERS, TDC
TDC are placed on the subgrade so each cylinder is in contact with the cylinders surrounding it. Due to the randomness in tire diameters precise circular arrangements are not possible. However, TDC should be placed so that each is circular and not squashed into an oval shape. It is preferable but not essential that each TDC is in touch with 4 other cylinders. A TDC should contact a minimum of 3 other cylinders. A placement should look like this photo.
STEP 3: Nailing TIRE-DERIVED-CYLINDERS, TDC to each other
When filling the TDC with a front end loader, a bull dozer or a grader, there is a tendency for the stone fill to collapse the side of the cylinder. To maintain their geometric integrity during the stone filling operation, each TDC is attached to the cylinders surrounding it at the point of contact. This attachment is the equivalent of wiring rebar before the placement of concrete. This attachment can be accomplished by a variety of methods. The simplest is to use a nail gun to drive a nail through adjacent cylinders where they come in contact. This means that each cylinder will be attached to three or four adjacent cylinders. The cylinders can also be screwed together or tied together with a string or wire. If the TDC are being filled by hand adjacent cylinder attachment is not necessary since cylinder geometry can easily be maintained. The following video shows how this TDC attachment process is accomplished with a nail gun.
STEP 4: Filling TIRE-DERIVED-CYLINDERS, TDC with Stone
The final step in placing Mechanical Concrete ® is filling the TDC with graded crushed stone material. The material specified is usually AASHTO #57 or AASHTO #3 for auto TDC. These stone particle gradations are specified since they are composed of stone particles of approximately the same size. This allows the stone to flow into the cylinder filling it completely without the need for compaction. It also maintains the void ratio necessary to allow water to freely drain through the material.
Motorized equipment can be used fill the cylinders from a bulldozer to a Gradall. The preferred method of filling is to use a suitably sized front end loader to fill the cylinders. The size of the loader will depend on the volume of stone to be placed and the efficiencies needed. The following video attachment shows how the TDC stone filling process is accomplished with a front end loader.
STEP 5: Mechanical Concrete ®Functioning—How it works
Live Loads applied to materials during the construction process are often greater than those experienced in day-to-day functioning. The following video shows Mechanical Concrete ® supporting the loads of heavy construction equipment easily due to its “rugged” qualities.