Evaluation of Strength and Resilient Modulus Characteristics of Fly Ash Geopolymer Stabilized Reclaimed Asphalt Pavement Material

Utilization of sustainable road construction materials has been the focus of research worldwide in recent times. Virgin aggregate is a primary material in the pavement industry; hence, finding an alternative is of extreme importance, concerned with the more prudent use of natural resources and the protection of the environment. The present research explored the usage of a significant portion of reclaimed asphalt pavement (RAP), activated with low calcium fly ash (FA) as a binding material. A liquid alkaline activator comprising sodium silicate solution (Na₂SiO₃) and sodium hydroxide (NaOH) was used for the alkali activation of the mix. The fundamental design parameters including Unconfined Compressive Strength (UCS) and resilient modulus (M_r) characteristics of the stabilized RAP:VA+FA geopolymer specimens were studied at room temperature. The resilient modulus (M_r) value in mechanistic-empirical analyses has been widely accepted in design/analysis of the pavement structures. Therefore, the present study aims to examine the resilient behaviour of the pavement base material stabilized with alkali activated low calcium Indian fly ashes, obtained from the southern region of India. The effect of additives on the microstructure of RAP:VA+FA blends were verified for one day and 28 days cured samples using X-ray diffraction (XRD) studies. Since the UCS and M_r values met the specified strength requirements, the stabilized mix can be used as a pavement base material.