Development of testing system for analysis of transverse contraction joints in Portland cement concrete pavement

The joints of Portland cement concrete pavement are cracks intentionally built in pavement to accommodate expansion and contraction due to shrinkage of concrete and temperature changes. Joints minimize and control random cracks due to temperature and moisture changes. Sealant is the material for sealing the joint. In recent years, the Florida Department of Transportation (FDOT) has been asked to approve narrower 1/8 in. concrete joints as opposed to traditional joints specified at 3/8 in. Thus, a series of new testing procedures were developed and executed to evaluate the differences between 1/8 in. and 3/8 in. joints. A new creep test (CRETA) was developed and conducted on joint sealant to determine its viscoelastic properties. Results indicated that the sealant is a linear viscoelastic material and that its creep response does not appear to be significantly affected by temperature fluctuations. Further creep tests were conducted under artificial aging conditions. Hot water aging appears to cause both self-leveling and non-self-leveling sealant to become softer and more ductile. Freeze thaw aging had no significant effect on properties. Oven aging had no significant effect on the self-leveling sealant, but it did cause non-self-leveling sealant to become more brittle. A new adhesive test (ADHESTA) was developed and conducted on joint sealant to determine its adhesive strength. Results indicated that the non-self-leveling sealant is stronger, but less ductile than the self-leveling sealant. A series of debris tests were conducted; they indicated that a "critical roughness" may be found for concrete joints. A series of adhesive strength aging tests was conducted; the results were similar to the creep test aging results. Moisture tests were conducted to evaluate the differences between 1/8 in. and 3/8 in. joints. Results indicated that the 1/8 in. joint dries significantly more slowly than the 3/8 in. joint, and that moisture significantly affects sealant adhesive strength. A new device (JPQCD) for evaluating joints in the field was developed to evaluate concrete joint adhesive strength. Results indicate that the 1/8 in. joint typically performs poorly when compared with the 3/8 in. joint. Further, data suggests that the 3/8 in. joint will perform closer to a joint's average strength when compared with a 1/8 in. joint. CRETA, ADHESTA, JPQCD, and a theoretical model were used to develop a finite element model for evaluating long-term performance of 3/8 in. joints compared with long-term performance of 1/8 in. joints. Results suggest that for both self-leveling and non-self-leveling field-poured sealant, the 1/8 in. joint is significantly less effective than the 3/8 in. joint. Based on all results, the 1/8 in. joint is not recommended.