Geocomposite

Geocomposites bond two or more geosynthetics into a single manufactured product, combining functions that would otherwise require separate layers installed one at a time. The most common configuration pairs a drainage core with a filter fabric on one or both faces: the core carries water within its own plane, while the fabric keeps soil out of it. Other combinations pair reinforcement with separation, or a barrier with a protection layer.

The value is largely economic. A few millimeters of engineered material can replace a foot or more of sand or gravel, which means less excavation, less imported aggregate, less weight bearing on the structure below, and fewer passes to install. Flow capacity is also a specified, tested property rather than something inferred from the aggregate a contractor happened to source. Typical uses include landfill leachate collection and cap drainage, retaining wall backdrains, roof and plaza decks, and drainage behind structures where space is tight.