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A pervious concrete pour is a three-step process - placing to elevation, compaction and curing. Unlike traditional concrete which looks for a smooth, finished surface, pervious concrete contractors strive for compaction, aggregate interlock and a porous surface.

The pour
Like traditional concrete, there are many different methods and equipment for pouring pervious concrete. However, since pervious concrete is a low-slump mixture, it cannot be pumped into place like traditional concrete. The most common methods of placement are directly from a ready-mixed truck, with a concrete buggy or by conveyor.

Pervious concrete is commonly poured in formed-out strips, says Dale Fisher, CEO of PCI Systems, LLC. Strips are poured every other to allow the pervious the proper amount of curing time. Current documents specify contractors pour strips between 12 and 20 feet wide. However, this can be a challenge when pouring very large areas that have tight scheduling deadlines. New equipment, such as laser screeds, allows contractors to pour larger areas without strips for situations like these.

Some pervious concrete can be placed with a concrete slipform paver. Slipform pavers do not use forms when pouring, so Fisher says most pervious placements using this equipment is done on slabs that do not need a definite straight edge, such as trail pathways.

Fisher likens a pervious pour to that of a long assembly line with the only difference being the crew members are working much closer together during a pervious pour. "Everything happens at the same time with pervious concrete. With regular concrete it's spread out," Fisher says. "With traditional concrete the whole slab is placed before the finishing operation even begins. With pervious concrete your placement, finishing and curing is all done at the same time."