Pervious concrete pavement, also know as porous concrete, is a unique concrete construction method that addresses environmental issues and supports green, sustainable growth. By capturing storm water and allowing it to filter into the ground, pervious concrete is an instrumental practice in recharging groundwater and reducing storm runoff. See how pervious concrete works below:
In pervious concrete, specific amounts of water and cementitious materials are mixed to create a paste that forms a thick coating around aggregate particles. Pervious concrete mixtures contain little or no sand, creating a substantial void content. Using sufficient paste to bind the aggregate particles creates a system of highly permeable, interconnected voids that drains quickly. Below is a test to check the readiness of a pervious concrete mix:
The pervious concrete project consists of three different concrete slabs constructed by the CIV 202 class during spring term 2013. Two slabs were were constructed outside, one with plastic lining enclosing the concrete slab and aggregate base to collect all of the stormwater entering the system, and the other lined with plastic around only the side walls of the concrete and base, allowing the stormwater to filter naturally into the soil. These two concrete slabs provide a control group and test study, respectively, to examine the pervious concrete slabs on the Oregon Tech campus.
The third portion of the project is an indoor pervious concrete slab. A wood frame was constructed by students to contain the same aggregate base and coarse pervious concrete layer as the outdoor slabs. In addition, half of the indoor slab has a fine grain pervious concrete layer laid on top of the coarse layer. The indoor slab is also equipped with faucets in order to regulate water flow for any studies performed on the pervious concrete in a controlled environment.
Below you will find more detailed descriptions of the three concrete slabs, including the materials used, and pictures and videos documenting the construction process of each of these pervious concrete slabs.
Outdoor Concrete Slabs
The two outdoor pervious concrete slabs were constructed simultaneously. First, two holes were dug out to 3' deep, 8' long and 2' wide. Next, the plastic was placed in both holes and perforated PVC pipe was placed in the center of those holes. They were then filled with coarse aggregate up to 2'-6". Frameworks for the concrete were placed over the aggregate in each of the foundations. Finally, the pervious concrete was placed, compacted, rolled and etched for a nice finish. The following videos document the construction process of the two outdoor pervious concrete slabs:
Indoor Concrete Slab
The indoor pervious concrete slab was casted in a wood frame constructed by the CIV 202 students in the Civil Engineering department. The reasons for constructing an indoor frame include that this configuration allows for concrete testing in a controlled environment and the frame can be moved to any location. The indoor frame was constructed using wood, screws, pvc pipe and faucets. The pvc pipes and faucets serve as an internal drainage system for testing water infiltration. The concrete was casted similarly to the outdoor slabs, with the addition of a fine grain pervious concrete covering half of the indoor slab. With the indoor slab containing two types of pervious concrete, infiltration tests can be conducted to analyze the efficiency of coarse grain and fine grain pervious concretes. You can see the construction of the indoor concrete slab in the pictures below: