Bunyan; Pervious

Pervious Slabs

Pervious concrete is designed to contain little or no fine aggregate. This leaves open space between course aggregate; up to 20% open space. The water/cement ratio is below .3 in an open matrix, drying at an accelerated rate. These conditions cause pervious concrete to be unusually delicate in the need for curing. We recommend the time available for placement and installation of poly sheeting of pervious slabs is fifteen minutes or less.

The Bunyan Striker cuts elevation and compresses the concrete at the same time. As it presses downward and forward, material is either swept forward or pressed down to elevation. Areas appearing to have less than 80% density are seeded with more pervious material. The tube runs back over it for another cut, compressing and shearing the surface. Once the strike is complete, poly sheeting is placed on the surface and cross rollers are used to compress the surface.

Many builders find pervious concrete difficult to handle because of it's non slump and it's open crumbling texture. The object is to reach a uniform fullness and density, a task made easy by the Bunyan Striker. Other methods of strike-off require the use of an elevated strike and a compression step to reach the desired density. Never use shims on formwork for elevated strike because there simply is not enough time.

Pervious paving has unique properties used to trap and treat contaminants carried by rain water. Water and Oxygen enter the pavement freely which enables hydrocarbons to digest in the slab and the gravel base material. Pervious concrete pavement has the potential to greatly enhance downstream water quality in our environment. The extra effort requited by ready mix producers and builders to pave pervious is an investment in our mother earth. Join with us as we hug a tree, think green and pave pervious.