Water Treatment Sludge–Calcium Carbide Residue Geopolymers as Nonbearing Masonry Units: Fid-Bau Portal

Water Treatment Sludge–Calcium Carbide Residue Geopolymers as Nonbearing Masonry Units

Suksiripattanapong, Cherdsak / Horpibulsuk, Suksun / Phetchuay, Chayakrit / Suebsuk, Jirayut / Phoo-ngernkham, Tanakorn / Arulrajah, Arul

Abstract

In this research, water treatment sludge (WTS) calcium carbide residue (CCR) geopolymers were evaluated as a sustainable masonry nonbearing unit. The WTS was a by-product from a water treatment plant, whereas CCR was a by-product from an acetylene gas factory in Thailand. Sodium hydroxide solution (NaOH) and sodium silicate solution ( ${Na}_{2} {SiO}_{3}$ ) were used for the geopolymerization process. The unconfined compressive strength (UCS), water absorption, and durability of WTS-CCR geopolymer were studied in this research. The test results indicate that the optimal liquid alkaline activator (L)/CCR ratios provided the maximum unit weight decrease with CCR contents for all of the ${Na}_{2} {SiO}_{3} / NaOH$ ratios evaluated. The optimal L/CCR ratios were found to be 16, 8, 5.33, 4, 3.2, and 2.67 for CCR contents of 5, 10, 15, 20, 25, and 30%, respectively. The ${Na}_{2} {SiO}_{3} / NaOH$ ratio of 70:30 was found to give the highest maximum unit weight and UCS among all of the WTS/CCR ratios tested. Three zones of UCS development with CCR content were evident: the active, inert, and deterioration zones. In the active zone, the UCS increased significantly as the CCR content increased, and the maximum UCS was attained at 10% CCR. In the inert zone, the UCS development was gradual. When the CCR content was more than 20% in the deterioration zone, a subsequent strength decrease was observed. The wet–dry (w–d) cycle strength, ${UCS}_{(w - d)}$ , depends primarily on the initial soaked strength, ${UCS}_{0}$ . A ${UCS}_{(w - d)}$ predictive equation was proposed for the assessment of initial strength to attain the required w–d strengths. Based on the UCS and water absorption requirements, an optimum ingredient consisting of 10% CCR and 70:30 ${Na}_{2} {SiO}_{3} / NaOH$ at room temperature curing can be recommended for nonbearing masonry units.