After more than a year of laboratory research work, NRMCA (National Ready Mix Concrete Association) engineers have developed a mixture proportioning software program for pervious concrete.
Proportioning pervious concrete mixtures is different compared to procedures used for conventional concrete. When developing pervious concrete mixtures, the goal is to obtain a design void content that will allow for the percolation of water. The challenge when proportioning a pervious concrete mixture is to ensure that when a design void content is targeted, a value that is close to that is attained. The other goal is to achieve an optimum paste of appropriate consistency to provide a mixture that is neither too dry nor too wet.
This software program helps the user establish mixture proportions for pervious concrete for a design void content and optimum consistency. Along with the software, two documents are included in the CD. The first document is a guideline that details the pervious concrete mixture proportioning methodology. The second document is a research report that provides experimental validation of the mixture proportioning methodology based on testing conducted at the NRMCA Research Laboratory.
A special feature of this software program is that the mixtures can be designed for a void content that is close to that measured by the newly standardized ASTM C1688 Standard Test Method for Density and Void Content of Pervious Concrete.
Pervious concrete is used for pavement applications to allow water to pass through the pavement structure thereby minimizing runoff and helping groundwater recharge. Its environmental properties are a prime reason why concrete should be considered a green building material.
NRMCA, based in Silver Spring, MD, represents the producers of ready mixed concrete and the companies that provide materials, equipment and support to the industry. It conducts education, training, promotion, research, engineering, safety, environmental, technological, lobbying and regulatory programs. For more information: http://www.nrmca.org