Optimization of CLS Content of Asphalt Mixtures Based on Balanced Mix Design Approach

Abstract

Over the years, there have been many studies on the performance improvement of asphalt mixtures using different materials and additives, especially those of the recycled variety, because of the environmental benefits they bring to the design. This study investigated the properties of asphalt mixtures made with different amounts of calcium lignosulfonate (CLS), which is a waste product, and used the Balanced Mix Design (BMD) approach to determine the appropriate mix design for CLS-containing mixtures. In this process, the results of the dynamic creep test were used as a measure of rutting resistance, the results of the indirect tensile test were used as a measure of moisture susceptibility, and the results of the Illinois Flexibility Index Test (IFIT) and Indirect Tensile Cracking Test (IDEAL-CT) were used independently as a measure of cracking resistance. On the other hand, since previous studies have suggested that CLS has antiaging properties, the specimens were made and tested in two groups: those with long-term aging and without long-term aging. So the objective was to determine the amount of CLS that should ideally be used as a bitumen additive in aged and unaged asphalt mixtures. The results showed that using 15% or 20% CLS will always yield acceptable outcomes in terms of BMD criteria for both aged and unaged conditions. However, a CLS content of 10% may also be acceptable for both aged and unaged conditions if IDEAL-CT results are used as the measure of cracking resistance.