Recycled Concrete Aggregate Stabilized with Lime-Fly Ash and Cement for Utilization as a Semirigid Base Course of Low-Volume Roads

Abstract

This study examined the mechanical characteristics of recycled concrete aggregate (RCA) stabilized with lime–fly ash (LFA) and cement for utilization as a semirigid base course of low-volume roads (LVRs). Several laboratory studies, which included modified Proctor compaction, unconfined compressive strength (UCS), indirect diametrical tensile strength (IDTS), durability, indirect diametrical tensile stiffness (MR), and indirect diametrical tensile fatigue tests, were considered to evaluate the performance of stabilized materials. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) analysis were carried out to understand the RCA morphology with stabilization at different curing periods. The test results demonstrated that RCA stabilized with a lime–fly ash content of 10% and cement content of 5% complied with a stabilized material’s strength and durability requirements for LVRs. EDS analysis found that the atomic Ca/Si ratio determined for RCA stabilized with LFA and C was less than the atomic Ca/Si ratio of RCA, which confirmed the microstructure improvement of RCA as a result of hydration products. The samples of RCA stabilized with 15% lime fly ash content were found to have higher MR and fatigue life values than those of RCA stabilized with 5% cement at the same curing period. Therefore, the performance of RCA stabilized with LFA is comparable to that of cement. The design of the pavement followed AASHTO guidelines. This research proposes a method to integrate RCA and fly ash for economical and sustainable construction of LVR. Natural aggregates from quarries have been used in the majority of road projects in India, which has resulted in the rapid depletion of nonrenewable natural resources and increased cost of construction. Simultaneously, vast amounts of construction and demolition waste (CDW) are generated in India. Therefore, the problems associated with rapid depletion of natural resources and the generation of CDW require an inexpensive and sustainable approach. LVRs constitute the major portion of the Indian road network, and generally are deprived of funds; for this reason, the use of CDW as an alternative to natural aggregate (NA) is advised for the construction of LVRs. Based on experimental results, this study provides insight into performance characteristics of RCA stabilized with lime fly ash and cement. The outcome of this study will help pavement engineering professionals. The use of RCA and fly ash in pavement applications is encouraged wherever possible to save both money and natural resources.