Production of cement-free concrete with fly ash and concrete scrap
Abstract
Production of cement-free concrete with fly ash and concrete scrap
Incoming article date: 26.12.2024The aim of the study was to determine the effect of the amount of alkaline hardening activator on the geopolymer binder consisting of ground blast furnace slag and fly ash. Ground blast furnace slag with fly ash was activated with sodium silicate (SN) at different contents of alkali solution (A). The results showed that an increase in the alkali activator content (SN:A = 5%:3% → 15%:4%) promotes an increase in the strength of concrete over the entire time interval of monitoring the strength gain. The addition of fly ash affected an increase in the compressive strength of concrete samples from 16 to 18% relative to the compositions without fly ash. Micro cracking is manifested in the compositions of geopolymer concretes without fly ash, activated by a sodium silicate solution at a higher silicate modulus. The reduction of the silicate modulus CH led to less microcrack formation and a more uniform structure, and the introduction of fly ash into the concrete mixture helps to eliminate internal stresses and the formation of microcracks on the surface of concrete samples.
Keywords: by-products, blast furnace slag, alkaline hardening activators, fillers, performance properties, strength, water absorption, development driver