A study on indirect tensile strength for the determination of resilient modulus of warm mix asphalt

Abstract

The advent of Warm Mix Asphalt (WMA) incorporating Recycled Asphalt Pavement (RAP) as a long-term solution to partially or totally participate in remediating the problem of global warming and the regression of environmental resources has been expanding and gaining interest throughout the world. The WMA-RAP technology created as an improved WMA technology has shown to possess mechanical properties closely similar to Hot Mix Asphalt (HMA). Though searching for environmentally sustainable asphalt technologies have become vital, the quest to construct economically sustainable highways cannot be neglected. The dynamic modulus tests (DMT) is among the most accurate yet expensive laboratory tests performed to determine the resilient modulus of asphalt mixes. Therefore, this paper aims to determine the resilient modulus of asphalt mixes (WMA-RAP and HMA) through both the indirect tensile strength (ITS) and the correlation formula method (CFM) and compares them against the dynamic modulus tests method (DMTM). Furthermore, this study utilises the resilient modulus found through CFM and DMTM to predict and compare the mechanical performances of asphalt pavement systems. Finite Element Modelling (FEM) and Linear Elastic Analysis (LEA) were used to modelling and analysing the mechanical behaviour of pavement systems. Both the WMA15% RAP and WMA30% RAP samples were mixed with 50/70 grade bitumen modified with Sasobit additive. The HMA samples on the other hand were mixed with non-modified 50/70 grade bitumen. Findings show that the resilient moduli of HMA and WMA-RAP mixes obtained through CFM is 77% close to the DMTM. In addition, the HMA and the WMA-RAP pavements with CFM and DMTM resilient moduli also show very close mechanical performance. This signifies that the CFM can be used as a reliable and cost effective alternative method to determine the resilient modulus of asphalt mixes.