Performance of Asphalt Concrete Crack Sealants in South Dakota

MSU Project Number 4W6436The ingress of surface water and snowmelt through cracks in asphalt pavements may reduce their service life due to wetting of sensitive subsoils or expansion during winter months. Asphalt crack sealants are a relatively low-cost pavement maintenance treatment that helps preserve the integrity of the road surface. The objectives of this research were to; 1) Evaluate eight different ASTM D6690 Type IV crack sealants at two different test sites in South Dakota, 2) Review South Dakota\u2019s Standard Specifications for installing asphalt crack sealant materials, and 3) Assess South Dakota\u2019s process to select suitable materials for their Approved Product List. A crack sealant index was used to assess the performance of the eight sealants at the two test sites. Results of the evaluation attributed a measured pavement contraction of 21% at one site with generally better performing crack sealants compared with 47% contraction measured at the second site. The reduced pavement contraction was likely a combination of milder winter temperatures and more consistent transverse crack spacing reflected through the concrete pavement beneath the bituminous overlay at this site. Sealant temperatures measured during installation and subsequent laboratory material tests were not consistent indicators of sealant performance and could not be used to identify the variation in performance of the same material at the two locations. South Dakota\u2019s installation specifications and process for establishing approved materials was similar to State departments of transportation with similar climates. Recommendations include future evaluations of wider (1 in. or 1.25 in.) routed reservoir widths and delayed chip-sealing activities to determine if additional improvements to South Dakota\u2019s crack sealing maintenance can be achieved