Effect of cement clinker type, curing regime and activator dosage on the performance of one-part alkali-activated hybrid slag/clinker composites

Abstract

One candidate for a novel binder is alkaline hybrid cement, which has more than 70% supplemental cementitious materials (SCMs) and a trace amount of an alkali activator but less than 30% Portland cement. This cementitious material offers high early strength, a more compact microstructure, and outstanding resistance to chloride penetration and sulphate attack, in addition to the benefits of alkali-activated materials (AAMs) and Portland cement. This study presents the findings of an experimental investigation that aims to clarify the effect of cement clinker type, curing regime, and activator dosage on the fresh, mechanical, durability, and microstructure properties of one-part alkali-activated hybrid slag/cement clinker composites (AAHC). Flow diameter, setting time, compressive strength, dry unit weight, flexural strength, drying shrinkage, sorptivity, and transport properties were evaluated. It was also aimed to investigate its effectiveness at high-temperatures, sulphate exposure, alkali-silica reaction (ASR), and freeze-thaw (F-T) cycles. A total of twelve AAHC mixtures were made with two GBFS/Clinker ratios of 70/30 and 90/10 and an external addition of 10% and 20% one-part alkali activator. Three cement clinker types and three curing regimes were adopted including oven, water, and steam. The results indicated that the water-cured mixture with GBFS/C3 ratio of 90/10 and activated by 20%MS had the greatest compressive strength of about 65 MPa. Steam and oven-cured mixtures with GBFS/C3 ratio of 90/10 and activated by 10%MS performed the best high-temperature resistance. The same mixtures cured in steam also had the best F-T resistance.