Durability of Transverse Sawcut Joints in Mid-Western Jointed Concrete Pavements
Dr. Dan Zollinger, PI, Texas A&M University
Dr. Jenny Liu, Co-PI, Missouri University of Science & Technology
This proposed project is comprised of an investigation into the role and extent that joint sealant effectiveness plays on the durability of sealed transverse sawcut joints in jointed concrete pavement that are subjected to deicing salts and freeze-thaw conditions. Specifically, this research will address the circumstances associated with the deterioration that occurs under the effect of oxychloride formation. This type of deterioration has been most prevalent in concrete pavements placed in the Midwestern parts of the US. This distress (Figure 1) is so extensive throughout Midwestern concrete pavements that it threatens the marketability of concrete pavements in the region. This proposed research will focus on aspects of the lesser-known distress in concrete (calcium oxychloride formation) that is caused by a chemical reaction between the chloride-based deicers and the calcium hydroxide (Ca(OH)2, (also denoted as CH). This reaction leads to the formation of calcium oxychloride, a deleterious reaction product that causes expansive pressures that damages a concrete pavement. As a consequence, the industry has a high level of interest in economic and effective solutions to prevent or minimize this distress type and has committed to in-kind contributions towards this research effort. Research has shown that some of the key factors in the incidence of calcium oxychloride formation are salt concentration and temperature which govern the threshold that must be exceeded in order to initiate the reaction. This research will seek to formulate a modeling approach to ascertain if the conditions in-situ warrant measures beyond the routine sealing of the joint to prevent damage from the formation of calcium oxychloride in the vicinity of a joint. The conditions will be characterized in terms of salt condition and temperature of the pore water in the concrete relative to the threshold or the activation energy for the reaction to occur.
Dr. Dan Zollinger
Dr. Jenny Liu