Innovative Modification and Testing of Asphalt Crack Sealants

Asphalt crack sealants are essential for preserving the integrity of asphalt pavements. They act as a barrier against water infiltration, a primary cause of base erosion and structural failure. However, these sealants are susceptible to degradation from traffic wear, weathering, and thermal stresses. This degradation manifests in multiple failure modes, including loss of cohesion, adhesion, and settlement. Being one of the most cost-effective pavement maintenance techniques, its market size is expected to be worth about $1.1 billion by 2028, with a 56% market share in North America alone. With extreme climatic events, sealants will have a tendency to fail more often. Therefore, this research effort investigated the incorporation of various modifiers into asphalt crack sealants and fillers to enhance their performance and durability, to perform beyond their designed life. Four different modifiers were selected and tested using a specific laboratory testing protocol targeting the failure modes observed in the field and ultimately leading to extended pavement lifespans and reduced maintenance expenditures. Furthermore, a novel test procedure to measure the coefficient of expansion and contraction of control and modified sealants was developed and calibrated as part of this study. These modifiers included an aerogel modified bituminous material, a pre-activated crumb rubber material, a recycled aerogel composite, and synthetic fibers.The testing program included durability and strength testing such as bonding strength, shear thinning, toughness, and tenacity; and thermal behavior testing such as expansion and contraction, thermal conductivity, and specific heat capacity. The coated aerogel modifier provided better toughness, tenacity, and bonding properties with improved thermal properties. The pre-activated crumb rubber reduced the effect of aging, whereas fibers showed promising results across most parameters. As for the recycled aerogel composite, thermal susceptibility was slightly improved, in addition to low temperature behavior for the filling material. Finally, a multiple decision-making criteria method was adopted to rank the best modifier for each material for parking lots and roadways followed by a life cycle cost analysis. A survey was conducted to rate the importance of each factor affecting performance, based on the integration of both quantitative and qualitative criteria, thereby accommodating diverse decision contexts and preferences.