Performance of Arizona’s SPS-4 Joint Sealing Experiment

Abstract

Currently, nearly all state highway agencies require sealing of transverse joints in jointed plain concrete pavement (JPCP). Joint sealing is estimated to increase initial construction costs by approximately 2 to 7 percent. Periodic resealing of joints also increases the costs of these pavements. Sealed joints are commonly believed to be beneficial to concrete pavement performance in two ways: in reducing infiltration of water into the pavement structure, and in reducing infiltration of incompressibles into the joints. However, despite the conventional wisdom concerning the need to keep transverse joints in concrete pavements well sealed, previous studies on the subject have not demonstrated that JPCP with sealed joints and JPCP with unsealed joints perform differently in terms of spalling, faulting, roughness, or deflections. Arizona is one of four states that has built and monitored experimental concrete pavement test sections with sealed and unsealed joints as supplements to the LTPP SPS-4 experiment. The supplemental experiments in three of these states differ from the other SPS-4 sites in that the pavements were constructed for the experiment, and incorporate a variety of joint sealant types and joint configurations, as well as narrow unsealed joints. The performance of the concrete pavement test sections and the joint sealants at the Arizona SPS-4 site has been monitored since the pavement’s construction in 1991. This monitoring has included deflection testing, distress surveying, profile measurement, test section length measurement, joint width measurement, and joint sealant condition evaluation. This paper presents the findings from nine years of monitoring of the performance of the pavements and joint sealants at the Arizona SPS-4 site.