Performance Evaluation of Polypropylene (PP) Modified Asphalt Concrete Mixtures

Abstract

ABSTRACT The use of polymers in pavements is on the rise in terms of delivering improved performance in form of enhancements of service life of pavements. The utilization of polymers in asphalt mixtures can significantly improve the performance indicators in form of extension in pavement service life and decrease in pavement distresses. The polymer fibre reinforcement of asphalt mixtures can elevate pavement performance indicators including high temperature stability and enhancement in fatigue resistance and stiffness modulus. Fibre Reinforced Asphalt Concrete (FRAC) is a suitable solution to improve the properties of asphalt mixtures. The purpose of this research is to examine the possibility of enhancing the characteristics of asphalt mixtures using PP fibres in asphalt mixture. The current study objectives focus on the performance evaluation of the PP fibre length effect in asphalt concrete mixes. Polypropylene (PP) fibre was added in proportions of 1% by weight of aggregate. PP fibre length variants used in the study are 13mm, 19mm, 25mm. PP modified, and conventional asphalt mixes were subjected to performance tests such as Tensile Strength Ratio (TSR), Resilient Modulus (M_R) and Indirect Tensile Fatigue Tests (ITFT). Results have indicated that inclusion of PP fibres has improved asphalt mixes properties. It has been observed that 13mm length of PP fibre dosage of 1% in asphalt mixtures outperformed other PP length variants. A higher length variant of PP fibre (19mm, 25mm) leads to decreases in the performance of this modifier due to an increase in air voids and non-uniform fibre distribution in the mix. It has been observed that the addition of PP fibres improves stiffness, fatigue resistance and moisture resistance. Moisture susceptibility is increased by 10.35% of modified mixes. Moreover, the inclusion of PP fibres also enhanced the stiffness of asphalt mixes up to 1.15 times to that of conventional mixes. Furthermore, the fatigue life of asphalt mixes has been enhanced by 85%. Overall, the asphalt mixtures with 13mm PP fibres with 1% content has the best results.