Production and performance of alkali-activated cold-bonded lightweight aggregate in concrete

Abstract

The research paper presents the strength and transport properties of concrete produced with alkali-activated cold-bonded lightweight aggregate (CLWA). The CLWA was prepared by the process of pelletization and was solidified (curing) by cold bonding method (ambient room temperature). The cold-bonding technique (at ambient temperature) is considered to be the best cost-effective approach to harden the CLWA with very less energy consumption as compared to sintering technique (which requires more than 1000 °C heat). The fly ash (80%) and cement (20%) with alkali activators (NaOH and Na2SiO3) were used to prepare CLWA. The addition of alkali activators in CLWA decreases the water absorption and increases the crushing strength. Moreover, to know the effect of fly ash (FA) on the strength and transport properties of cold-bonded lightweight aggregate concrete (CLWAC), the sand was partially replaced with the FA and their results were compared with normal weight concrete (NWC) of equal composition. Experiments were conducted on concrete to study the compressive strength, water sorptivity, chloride ion permeability and water permeability. The NWC exhibited better strength than CLWAC due to higher open porosity and lesser strength of CLWA. The scanning electron microscopy images presented the pore structure of CLWA and concrete. The remarkable improvement in strength and transport properties of concrete was observed (CLWAC & NWC) due to an addition of FA as a partial substitution of the sand. This value-added effect can encourage high volume utilization of FA in concrete.