Sunflower straw ash as an alternative activator in alkali-activated grouts: A new 100% waste-based material

Alkali-activated grouts (AAGs) are increasingly used to replace ordinary portland cement owing to their several advantages. The mechanical properties and environmental aspects of AAGs are affected by the type of activator. In this study, the effects of sunflower stalk ash (SSA) and commercial alkaline reagents on the mechanical properties, microstructures, and CO2 emissions of geopolymer grouts were investigated for the first time using blast furnace slag and black rice husk ash as precursors. The results indicated that the potassium and calcium salts in the SSA promoted the formation of C(K)-A-S-H and C–S–H. The compressive strength of the SSA-activated grouts was higher than that of the slurry prepared using commercial products (24.88 vs. 11.59 MPa). Using SSA instead of commercial reagents can reduce kg CO2-eq/t powder by 84.4 %.