INSTALLING TDA
In civil engineering applications, TDA is usually installed in 18-inch layers. After kneeding and compaction (repeated as necessary until final elevation is achieved), a geotextile fabric may be used to cover TDA. On top of that, 18-24 inches of other aggregate is used to compress the compacted TDA. Then, depending on the project design specifications, the surface can be built as usual.
TDA can be easily spread and compacted with conventional construction equipment. Typically, the material is delivered to the job site using walking-floor trailers, and excavators and bulldozers are used to place the material. Once the TDA is spread over the site in lifts, it is compacted with a compactor or bulldozer by running over it several passes. (In some applications, a drum roller is used for compaction.) As these vehicles move over the fill, the pieces tend to interlock, orienting parallel to the horizontal shear plane as they form a snowshoe-like layer.
"Dribbling" of tire pieces is reduced significantly by isolating the equipment spreading the TDA from the equipment moving soil and keeping heavy equipment to the area holding the TDA. (Avoid moving this equipment in and out of other construction areas.) Simple maintenance of equipment such as cleaning tire pieces out of tracks ensures smoother operations, as well.
Remember that TDA will have elevation shrinkage when compressed with the 18-24 inches of soil. To achieve the correct design depth following compaction, engineers and designers recognize that approximately 50% more loose volume TDA is required compared to conventional aggregate.