Performance of hot bituminous mixes admixed with blended synthetic fibers

Abstract

With increased traffic loads and climate changes, even well designed bituminous surfaced roads are fast deteriorating. Hence, in recent years, research has been focusing on the control of fracture and permanent deformations in flexible pavements. In order to address issues of rutting, fatigue, and low-temperature cracking, different types of polymer modifiers have been utilized. The use of blended synthetic fibers as a low cost modifier in bituminous pavement mix was found to be effective in improving performance compared to other modifiers, as an attractive option. In this study, a mixture of polypropylene and aramid fibers was introduced to evaluate the performance characteristics of a bituminous mixture. The objective of the study was to evaluate the mechanistic properties of conventional and fiber-reinforced bituminous mixtures and implications of fiber addition on thickness and cost reduction of bituminous layers. Effect of addition of fiber on pavement design has also been studied. The laboratory experimental program included indirect tensile strength tests, wet indirect tensile strength after water and MIST (Moisture Induced Sensitivity Test) conditioned, dynamic creep and resilient modulus at different temperatures. This paper reports of the reduction of thickness of pavement also cost analysis with the addition of fibers and resulting properties. Optimum fiber dosage was determined to be 0.05% by weight of mix based on laboratory performance of mix. The results show that fiber improved the mixture performance by a drop of rut depth up to 50% and adding fatigue resistance up to 400%. Moisture resistance and indirect tensile strength of fiber mixture is increased by 9 to 14% in comparison to conventional mix. While the addition of fibers resulted in 2% higher cost, manifold increase of performance and 13% reduction in pavement thickness would justify the act.