Abstract:
This research investigates unconfined compressive strength development in recycled pavement base material improved by fly ash and calcium carbide residue geopolymer at curing times of 7, 14, 28, 60, and 90 days. This research studied the effect of liquid alkaline activator content comprised of sodium silicate (NS) and sodium hydroxide (NH) with NH concentration of 8 molars, the RCR:CCR:FA ratios, and the NS:NH ratios. The test result showed that the maximum dry unit weight of the RCR:CCR:FA geopolymer sample decreased as the FA increased due to the lower specific gravity of FA. The 7-day unconfined compressive strength increased as FA content increased due to the increased amount of Si and Al. Sample with optimum liquid content and NS:NH ratio of 2 gave the maximum unconfined compressive strength of 9.88 MPa. Based on the Department of Highways (DOH) standard, All ingredients passed the DOH standard. The proposed equation is beneficial for estimating the unconfined compressive strength of RCR:CCR:FA geopolymer when 28-day unconfined compressive strength was known.