1661298 - Amine Impregnated Zeolite in Low Carbon and Conventional Hot Mix Asphalt to Reduce Carbon Footprint

Global temperature is rising continuously, and carbon dioxide emission is responsible for this climate challenge. Asphalt paving materials require an extremely high temperature, contributing to carbon emissions. In addition, it often uses lime or liquid amine as an additive to reduce moisture damage. Lime production is another contributor to a significant amount of carbon emissions. In the case of liquid amines, they lose their long-term efficacy of pavement service life due to weathering and UV radiation. In order to prolong the efficacy of amines, zeolite can be used as a protector. In this study, the performance of PG 64-16 Low Carbon asphalt binder is compared to conventional PG 64-16 asphalt binder. In addition, we investigated the effect of amine-impregnated zeolite (AIMZ) on asphalt mixture performance. PG 64-16 Low Carbon is made with 10% post-consumer plastic which reduces CO₂ emission from liquid asphalt by approximately 5%. AIMZ was used to investigate the use of zeolite as a carrier, which can protect the liquid amines from weathering effects and release them gradually over the years. Ethylene diamine and 90-92% clinoptilolite zeolite were used in this study. The performance of AIMZ is compared to that of amine and zeolite separately and a commercial amine-based antistripping liquid named LOF 65-00.

Mixes with three different aging levels were prepared – 3-days, 5-days, and 7-days, which represent roughly 4 years, 8 years, and 12 years of field aging, respectively, in the weather of Southern California, according to NCHRP Research Report 973. The Tensile Strength Ratio (TSR) test was used to evaluate the fracture resistance and resistance to moisture-induced damage. The Hamburg Wheel Tracking (HWT) test was used to examine the rutting resistance. The results showed that the dry tensile strength of PG 64-16 Low Carbon binder was 30-40% lower than the conventional binder for all additives at every aging level. Similarly, the wet tensile strength of low carbon binder was also significantly lower than the conventional binder. For 7 days of aging level, AIMZ slightly improved the wet tensile strength. For 5 days of aging level, AIMZ slightly improved the wet tensile strength than the commercial antistrip for low carbon binder but showed a similar effect for conventional binder. The rutting resistance of specimens with low carbon binder was similar to conventional binder. There were no significant differences in rutting resistance among different additives. Further investigation is needed with varying percentages of amine and different types of zeolites; however, this study is one step forward in evaluating amine-impregnated zeolite as an antistrip that can be environment-friendly and effective in long-term pavement service life.