Minimize Premature Distresses in CRCP (FHWA/TX-14-0-6687-1)
The long-term performance of continuously reinforced concrete pavement (CRCP) has been quite satisfactory in Texas, providing an important network of highways with heavy truck traffic and minimal maintenance. Field evaluations of the performance of CRCP in Texas reveal that a substantial portion of distresses is not necessarily due to structural deficiencies of CRCP. Rather, many distresses appear to be due to construction and material related issues and to a lesser extent, imperfections in design details. Since these distresses occur long before structural distresses develop, they are considered premature distresses. The most effective way to prevent or minimize premature distresses is to identify the mechanisms of distresses, develop appropriate special provisions to existing specifications or special specifications, and modify existing design standards. Distresses at transverse construction joints (TCJs) were one of the most frequently observed and efforts were made to identify the mechanisms of those distresses and develop or improve design standards or specifications. Field evaluations of concrete and steel behavior near TCJs were made using various gages. The analysis of the data indicates that the current practice of placing additional tie bars at TCJs, along with poor construction practices, are the major causes of the distress. There is a large difference in the behavior of reinforcement between additional tie bars and longitudinal steel that is continuous through transverse construction joints. The premise that additional tie bars at TCJs will behave the same way as longitudinal steel, thus reducing steel stresses of longitudinal steel at TCJs, keeping the joint widths tight, and improving TCJ performance, is not necessarily correct. Also, the use of additional tie bars makes the consolidation of concrete at TCJs difficult due to the reduced spacing between longitudinal reinforcing steel. Not placing additional tie bars at TCJs, and the use of relief transverse saw cut joints near TCJs, along with improved construction practices at TCJs, will minimize the distresses.
Authors: Sureel Saraf, Pangil Choi, Sungwoo Ryu, Soojun Ha, Tewodros Ghebrab, Moon C. Won