Effect of water–binder ratio on the mechanical properties of calcium hydroxide-based alkali-activated slag concrete

This paper presents mechanical properties of calcium hydroxide (Ca(OH)2)-activated ground granulated blast-furnace slag (GGBS) concrete with different auxiliary activators in order to provide basic data for developing the mixing procedure and design models for structural concrete. Twelve concrete mixes were prepared with the main parameters of water–binder (W/B) ratio. The measured mechanical properties were compared, wherever possible, with design equations specified in ordinary Portland cement (OPC) concrete code provisions. The investigated Ca(OH)2-based AA GGBS concrete showed an enhanced workability, delayed slump loss and similar increasing rate of compressive strength against W/B ratio to that observed in OPC concrete. Similarly to OPC concrete, mechanical properties of Ca(OH)2-based AA GGBS concrete could be expressed as a power function of compressive strength (fc′). The values of the power in the determined equations could be approximately set to be 0.5 for modulus of elasticity, 0.65 for modulus of rupture, tensile strength and direct shear strength, and 0.75 for bond strength. Overall, the present test results revealed that the tested Ca(OH)2-based AA GGBS concrete has a considerable potential for practical application to structural concrete when the W/B ratio is lower than 30%.

▸ This study examines the mechanical properties of the Ca(OH)2-based AA GGBS binder. ▸ The measured properties are compared with design equations of OPC concrete provisions. ▸ The empirical equations to predict the properties of AA GGBS concrete tested are proposed. ▸ We find that Ca(OH)2-based AA GGBS concrete with water-binder ratio below 30% has a potential for practical application.