Investigation of fire and chemical effects on the properties of alkali-activated lightweight concretes produced with basaltic pumice aggregate

•The strength properties of AALWCs with BFS and FA are evaluated in this paper.•The effect of acid, sulfate and elevated temperature on the AALWCs are studied.•The microstructures of the AALWCs are analysed by SEM, EDS, XRD and PLM. This paper evaluates the properties of alkali-activated lightweight concretes (AALWCs) produced with basaltic pumice aggregate. The AALWC mixtures using the replacement ratios of 0, 25 and 50% blast furnace slag (BFS) by weight of fly ash (FA) are produced in addition to a reference lightweight concrete (RLWC) produced by only Portland cement. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) are employed as activating agents in the AALWC mixtures. The experimental studies are performed to investigate the properties of AALWCs. In these studies, the strength properties like compressive strength (fc), flexural strength (ffs) and splitting tensile strength (fsts) are determined. Moreover, the durability properties such as water absorption, acid and sulfate attacks resistance, and behaviour at elevated temperatures are studied. The residual fc and mass loss of lightweight concretes (LWCs) including the RLWC are examined after the durability tests. The results of AALWCs are compared with each other and RLWC. The change in the microstructures of LWCs due to the elevated temperatures are researched by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) spot, X-ray diffraction (XRD) and polarized light microscope (PLM) analyses. The results show that the AALWCs have superior durability properties than the RLWC. Moreover, the recovery of wastes such as BFS and FA contributes to both reducing environmental pollution and reducing CO2 emissions.