By: Richard B. Rogers, PE
During the recent Transportation Research Board meeting, Katie A. Larsen, University of Texas at Austin, reported some interesting findings regarding her studies in asphalt-rubber permeable friction courses (PFC). During the Distress Analysis Work Group Committee meeting her preliminary findings indicated that unacceptably high levels of zinc were present in the runoff water.
These elevated zinc levels were not found in an adjacent PFC that did not contain rubber. Apparently the zinc leaches out of the rubber in the PFC and exceeded maximum thresholds after prolonged dry periods. This creates a problematic issue, because it is my understanding that the rubber/latex is needed to improve the noise reduction and the long-term performance that the asphalt-rubber PFC is touted for.
"This blog was previously posted in the Cement Council of Texas' "Texas Cement and Concrete Blog" (now inactive) and was carried forward to the current blog ("Cementx Pavement Blog") as it contains content that may be of interest to the reader".
The Cementx Pavement Blog seeks to make pavement owners, engineers and contractors smarter about selecting, designing, constructing and maintaining pavements. New blog postings began February 1, 2017; however, we carried over pavement-related blog postings from our older blog, the "Texas Cement and Concrete Blog," which ran until December 2016.