Strength and workability of one-part sodium carbonate activated mortar incorporated with silicomanganese slag

Abstract

This research utilized sodium carbonate (Na2CO3) as an alkaline activator to produce one-part alkali-activated mortar (AAM) with silicomanganese (SiMn) slag as the aluminosilicate precursor. In the experiment, the effect of Na2CO3 dosage (4%, 6%, 8%, 10%, 12%) and binder replacement with ordinary Portland cement (OPC) (10%, 30%, 50%) on the compressive strength and workability of AAM was investigated. To improve the workability, several types of superplasticizer (SP), including MasterGlenium ACE 389 (MG) and sodium naphthalene sulfonate formaldehyde (SNSF), and retarder, including REAL SET 231 (RS231) and vinegar, were incorporated. The relationship between strength and workability of one-part AAM was then established. The results showed that the increasing Na2CO3 content from 4% to 10% improved the strength by 2 times but reduced workability by 7.8% due to the increased alkalinity and OH- concentration. The incorporation of up to 50% OPC further increased the strength by 3.2–5.3 times due to the synergetic effect of alkali activation of SiMn slag and cement hydration. In addition, SNSF-type SP outperformed MG-type SP in terms of workability and compressive strength. Both the RS231 retarder and acetic acid enhanced the workability by 8%–48% and strength by 10.5%–28.3%. A quadratic regression equation with R2 values of 0.58–0.81 was developed to correlate the strength and workability of one-part AAM.