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VTRC Project # 67775, TPF-5(045), Current crack sealant specifications focuses on utilizing simple empirical tests such as penetration, resilience, flow, and bonding to cement concrete briquettes (ASTM D3405) to measure the ability of the material, to resist cohesive and adhesion failures. There is, however, no indication of the pertinence of these standard, tests to predict the success of field installation and sealant performance. In an effort to bridge the gap between, sealant fundamental properties and field performance, performance-based guidelines for selection of hot-poured, crack sealants are currently being developed. This report focuses on the development of the apparent viscosity, test method. This test uses a modified version of the Brookfield rotational viscometer. Based on the results of, this study, the measured apparent viscosity of hot-poured crack sealant using SC4-27 spindle at 60rpm (20.4s-1), at the recommended installation temperature was determined to be reasonably representative of sealant, viscosity at shear rates resembling field application. To ensure measurement consistency and stability, a 20min, melting time and a 30-s waiting time prior to data collection are recommended. To establish precision and bias, for the test, a round robin testing was conducted among seven laboratories. Average coefficient of variation, within and between laboratories was found to be 2% and 6%, respectively. Using the data from the round robin, testing, and based on ASTM precision and bias standard (ASTM practices C802 and C670), maximum, permissible differences within a laboratory and between laboratories were found to be 4.6% and 16.9%., Considering the high polymer or crumb rubber content in crack sealants and sealant temperature sensitivity, the, repeatability and reproducibility of the developed test is within an acceptable range. These values are, comparable to those of asphalt binder: 3.5% and 14.5% based on ASTM D4402-02 and 3.5% and 12.1% based, on AASHTO 2006 T316.

VTRC Project # 67775, TPF-5(045), Crack sealing is a common pavement maintenance treatment because it extends pavement service life significantly., However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly, empirical and only provide a qualitative measure of bond strength, they cannot predict sealant adhesive failure accurately., Hence, there is an urgent need for test methods based on bituminous sealant rheology that can better predict sealant field, performance. This study introduces three laboratory tests aimed to assess the bond property of hot-poured crack sealant to, pavement crack walls. The three tests are designed to serve the respective needs of producers, engineers, and, researchers. The first test implements the principle of surface energy to measure the thermodynamic work of adhesion, which is the energy spent in separating the two materials at the interface. The work of adhesion is reported as a measure of, material compatibility at an interface. The second test is a direct adhesion test, a mechanical test which is designed to, closely resemble both the installation process and the crack expansion due to thermal loading. This test uses the Direct, Tensile Test (DTT) machine. The principle of the test is to apply a tensile force to detach the sealant from its aggregate, counterpart. The maximum load, Pmax, and the energy to separation, E, are calculated and reported to indicate interface, bonding. The third test implements the principles of fracture mechanics in a pressurized circular blister test. The apparatus, is specifically designed to conduct the test for bituminous crack sealant, asphalt binder, or other bitumen-based materials., In this test, a fluid is injected at a constant rate at the interface between the substrate (aggregate or a standard material), and the adhesive (crack sealant) to create a blister. The fluid pressure and blister height are measured as functions of time, the data is used to calculate Interfacial Fracture Energy (IFE), which is a fundamental property that can be used to predict, adhesion. The stable interface debonding process makes this test attractive. This test may also provide a means to quantify, other factors, such as the moisture susceptibility of a bond. In addition, the elastic modulus of the sealant and its residual, stresses can be determined analytically. While the direct adhesion test is proposed as part of a newly developed, performance-based guideline for the selection of hot-poured crack sealant, the blister test can be used to estimate the, optimum annealing time and installation temperature.