EVALUATION OF GEOPOLYMER TREATED BASE AS A POTENTIAL PAVEMENT REHABILITATION TECHNIQUE

Abstract

Full Depth Reclamation (FDR) is an innovative technique that involves recycling of existing distressed flexible pavements and their underlying layers, into a new stabilized base course. The technology is capable to resolve all concerns related to traditional road rehabilitation methods such as limited depth treatment, degradation of natural resources, excessive energy consumptions and others. The laboratory study is dedicated to a sustainable mix design of treated base layer by incorporation of Geopolymer to fully replace cement in road rehabilitation projects. No wonder FDR with cement (FDR-PC) provides a strong and durable base. However, utilization of cement raises a significant concern over the sustainability aspect of this technique. Release of carbon dioxide during cement production is a huge concern across the globes as it contributes significantly towards global warming and corresponding climate change disasters. Therefore, keeping in mind the adverse effects of cement production to environment, there is a wide scope to explore pavement rehabilitation using geopolymer (FDR GP) rather than confining solely to FDR-PC. A geopolymer based precursors like fly ash (FA) combined with ground granulated blast furnace slag (GGBS) along with sodium hydroxide (NaOH) as an alkaline activator was studied to replace cement in FDR. The strength characteristics like unconfined compressive strength (UCS), flexural strength, and durability characteristics like wetting & drying (W/D) tests were done for all mixtures. The findings indicated that geopolymer-based stabilized mixtures exhibited promising performance for both strength and durability characteristics. Geopolymer binder prepared using 1 molar NaOH solution, FA: GGBS as 70:30 was able to exhibit 7 days and 28 days UCS of 4.75 MPa and 8.02 MPa respectively. The flexural strength of the same mix after 7 and 28 days of curing was found to be 1.045 MPa and 1.722 MPa respectively. The average percentage weight loss after 12 cycles of wetting-drying was recorded as 4.46%. Therefore, satisfying all the requirements of stabilized base, BGP1 was reported as the optimum mix for the current study.