Assessment of Ground Tire Rubber Content in Bituminous Sealants with Destructive and Non-destructive Methods

Ground tire rubber (GTR)-filled bituminous crack sealants are widely used to repair the cracks generated over the service life of asphalt pavements stemming from long-term exposure to the natural environment and cyclic stresses from traffic loads. GTR content plays a crucial role in the field performance of GTR-filled bituminous crack sealants. Thus, the accurate measurement of GTR content is of paramount importance to predict the performance of the sealant, including pouring viscosity, adhesion to asphalt concrete, and flow ability into micro-voids within the crack. Here, a visual technique was proposed to evaluate non-destructively the GTR content of bituminous crack sealants. The method was applied to several commercial bituminous crack sealants of unknown composition. The results of the optical non-destructive method were also compared to those from the traditional destructive method, which consisted of the combination of solvent extraction and pyrolysis of the residual solid. An acceptable level of linear correlation between the two methods, 0.80, verifies the capability and reliability of the proposed non-destructive visual method of quantifying GTR content in bituminous crack sealants having a uniform background in optical microscope images.