Performance evaluation of additive-modified geopolymer concrete under normal and elevated thermal exposure

Abstract

ABSTRACT This research work aims to explore the effect of Spinacia oleracea (SO), Calotropis gigantea (CG), and Polyethylene Glycol (PEG) on the physical and durability characteristics of geopolymer concrete (GPC) at normal curing conditions and at 600 °C for 2 hours. Fly ash and GGBS were used as binder materials, and additives were added at a range of 0.2% to 1% of binder weight. Slump and compactness tests were used to determine workability, and hardened properties were tested by strength parameters, water absorption, sulphuric acid resistance, and RCPT. All mixes had good workability at 0.6% dosage. PEG performed better, and the mix containing 0.6% PEG had a compressive, split and flexural strength of 41.3, 2.74 and 4.28 MPa at 28 days. It also had the lowest water absorption of 2.38%, lowest acid strength reduction of 6.67%, and lowest RCPT value of 2530 coulombs. SEM results showed a compact matrix with fewer pores and better bonding. Although high temperature conditions decreased the properties, the PEG mixes had better residual strength and durability.