Preparatory Study about Effect of Feldspar on Properties of Alkali-Activated Slag Concrete

In spite of feldspars being the most plentiful components in the crust of the earth, their uses in alkali-activated materials are still too limited. In this work, for the first time, the effect of different ratios of potassium feldspar on the properties of alkali-activated slag (AAS) concrete was studied. The slag was partially replaced with 10 to 50% feldspar with a stride of 10 wt. %. The effects of feldspar on the workability, compressive strength, splitting tensile strength, water absorption, and total porosity of AAS concrete were investigated. Different techniques were applied to investigate the crystalline phases, hydration products, and microstructures of the critical samples. The results showed a positive effect of feldspar on workability, of which the workability increased with increasing feldspar ratio. The incorporation of 10% feldspar has a positive effect on compressive strength, splitting tensile strength, water absorption, total porosity, and refining the microstructure, while higher ratios than 10% have a negative effect.