Members of ASTM Subcommittee C9.49 are attempting to standardize the testing methods for pervious concrete. There is much interest in this topic, as committee secretary Jenny Hitch reports more than 120 people are members of this committee, making this one of the largest groups in C-9.
When it formed last summer, subcommittee leaders established five work groups. Leaders of these work groups reported their progress at their meeting in DecemberField Permeability
Dr. Heather Brown reported that the task group had considered four methods, but has focused on the field permeability test method developed by Middle Tennessee State University (MTSU) since it corresponded well with similar tests.
Members conducted a round robin test using the MTSU method, and initial results suggested that it worked well. The method may be revised to include a section for pre-wetting the test area, reducing the head pressure from 1 inch to 1 cm to reflect the true rain event, and a necessary flow.
The task group plans to review the round-robin test data and ballot some questions in February. For more, e-mail firstname.lastname@example.org.Compressive Strength
The task group, led by Mark Kurtz, is attempting to develop a standardized compressive strength test for pervious concrete. The procedure is difficult because of the challenges of standardizing consolidation techniques, capping material, and choosing an appropriate cylinder size.
Kurtz presented a table reflecting a series of round robin tests. He also showed a short summary of tests studying the consolidation techniques. Kurtz hopes to conduct a second group of round robin testing in the next few months. E-mail email@example.com.Flexural Strength
In a report given on behalf of Stefan Bernard, the task group presented some very preliminary ideas on a flexural test procedure.
The group believes that a new beam test that does not radically differ from existing methods should be developed for pervious concrete. It proposes that the direction of bending should correspond with the direction of placement. And the new test should be developed for low-density, high-permeability mixes.
It also proposes that the new pervious beam tests should have two versions: a simple section for plain pervious concrete and a more complex section for fiber-reinforced pervious concrete.
The task group is working on three questions: What span length should be used? What spreader beam width should be used? And should there be a post-crack assessment in the test for fiber-reinforced concrete? For more information, e-mail firstname.lastname@example.org.Fresh Concrete Density and Voids Content
Michael Davy reported the task group conducted a round robin lab test outlined in a written procedure based on using a standard Proctor Hammer for freshly mixed pervious concrete. Initial results indicated that the method using 20 blows per lift, with two lift sample size, yielded a high degree of repeatability. E-mail email@example.com.Hardened Concrete Density and Porosity
In brief report given on behalf of Michael Leming, (firstname.lastname@example.org), the group learned that the task group was in the midst of evaluating historical information based on a field test developed by staff at the University of South Carolina, and a BASF draft specification, perhaps using ASTM C140. More information will be presented at the June meeting. Related Article