Performance evaluation of hot-applied sealant for asphalt pavement with consideration of the ash content

Abstract

The hot-applied sealant is widely applied for sealing the cracks of asphalt pavement, in which the filling equipment is always blocked during the installation. The high proportion of ash particles generating the high segregation and low liquidity of sealant is a critical reason for equipment blockage. Therefore, this study aims to explore the influences of ash content on the stability and fluidity of sealant. Six commonly used sealants following the specification requirements were selected in this study. The methodologies involve proposing an ash content test to enhance the calcination efficiency of sealant samples, conducting the segregation and rheological tests including amplitude sweep (AS), temperature sweep (TS) and multiple stress creep recovery (MSCR) tests to evaluate the stability and fluidity of sealants, and utilizing the gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) tests to acquire the specific chemical properties of sealants. The results indicate that the modified ash content test protocol proposed, calcining the sealant by mixing with the steel balls, is effective for fully calcining. The sealants with high ash content values always exhibit severe segregation and low thermal stability. The complex modulus curves, phase angle curves, black space diagrams, Han curves, and non-recoverable creep compliance (Jnr) values derived from the rheological tests present that the ash particles lead to poor stability and high elasticity of sealants. Furthermore, the FTIR tests imply that the S1 sealant was modified with most additives among six sealants, while the GPC tests point that the ash particles are not related to the molecular size of sealants. Moreover, it is recommended that the ash content index should be included in the existing evaluation system after the weak correlations with other indexes were discovered.