Mechanistic service life prediction of rigid pavement joint sealant: a new laboratory testing technique
A new method to evaluate the performance of sealants used in rigid pavement joints was developed. A special fixture, attached to a servo-hydraulic testing machine, was designed to transfer applied cyclic shear deflection to a sealant sandwiched between two 51 x 51 x 51 mm portland cement concrete (PCC) cubes at a constant horizontal deflection. The new testing method simulates field conditions where shear deflection is caused by vehicular loading, while horizontal deflection is caused by slabs contraction or expansion due to temperature variation. Two commercially available, a low modulus silicone (sealant A) and a polyurethane (sealant B), one-component sealant types were evaluated at different joint widths, number of freezing and thawing cycles, and horizontal deflections. Two types of aggregates were used in the PCC mixes to evaluate the effect of aggregate on sealant performance. A limited number of specimens were evaluated for sealant failure using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Dynamic Shear Rheometer (DSR) was used to estimate the viscoelastic properties of sealants.