Innovative test method for the reliable evaluation of joint sealants in concrete pavements

Joint sealants as indispensable filling systems in jointed plain concrete pavements (JPCP) are permanently exposed to various stresses during their service life, which often leads to a replacement of the sealing after approx. 7 to 10 years. Aside from seasonal unsteady climatic changes, the cyclical stresses caused by traffic and the ageing of joint sealants are especially significant. Considering the rising number of damages that occur within the overall "joint" system, an increased demand for a durable solution is requested as it is a relevant element for the life cycle costs of concrete pavements. In this context, a testing and ageing method was developed which comprises of the entire "joint" system, including the saw-cut concrete joint flanks, the primer as well as the joint sealant. This procedure depicts the decisive scenarios of in-situ stresses and allows the characterization of joint sealants. For this purpose, specimens were subjected to horizontal and vertical loads (static/cyclic) as well as to various ageing effects (temperature conditioning, UV-conditioning and freeze-thaw-cycles). After conditioning, a significant influence of the artificial ageing on the residual strength was observed in the tensile/shear tests. By comparing the artificially aged samples tested in the laboratory with extracted and in-situ aged samples, a reliable correlation was determined. Considering these system tests an initial approach was established which enables the evaluation of joint sealants in both unaged and artificially aged conditions on the basis of scientific parameters and limits.