A Study of Compressive Strength and Sulfuric Acid Resistance of Alkali Activated Mortar Made with Calcium Carbide Residue and Fly Ash Mixtures

This research aims to study the compressive strength and sulfuric acid resistance of alkali activated mortar made with calcium carbide residue (CCR) and fly ash (FA) mixtures at the ratios of 15 to 85, 30 to 70 and 45 to 55 by weight, sodium hydroxide (NaOH) concentration of 4, 6, 8 and 10 molar, binder to fine aggregate ratio of 1 to 2.75 by weight and a liquid to binder ratio of 0.85. The testing program was divided into 2 parts which were compressive strength and weight change of mortar immersed in 5% by weight of sulfuric acid solution. The test results indicated that increasing of NaOH concentration from 4 to 8 molar and calcium carbide residue content from 15 to 30 led to higher compressive strength of mortar. Mortar made with CCR and FA at the ratio of 30 to 70 by weight and activated with 8 molar of NaOH gave the highest compressive strength at 28 days which was 45.0 MPa. The resistance of mortar due to 5% of sulfuric acid solution was decreased with the increasing in calcium carbide residue content which could be observed from the cracking in mortar since the early age of the immersion.