Development of Ultrafine Slag-Based Geopolymer Mortar for Use as Repairing Mortar

摘要

Geopolymer has earned a significant position in the construction industry. A number of researchers have attempted to use it as a concrete-repairing material. To enrich the literature with results on geopolymer as a concrete-repairing material, the present study reports experimental works performed on geopolymer mortars prepared from ultrafine ground granulated blast-furnace slag. Geopolymer mortars were prepared with alkali activators composed of (1) sodium silicate and sodium hydroxide, and (2) only a sodium hydroxide solution, and tested to study the setting time, workability, and strength-gain behavior. Furthermore, to the sodium hydroxide-activated mortars, certain admixtures such as fly ash and superplasticizer were added in various quantities to study their effect on the mentioned properties. The effect of alkali activator concentration and time of addition of superplasticizer has also been observed through the laboratory experiments. A total of 504 cube samples for a total of 28 different mortar mixes were prepared and tested for observing strength-gain behavior. Results indicated that sodium silicate-free mortars were better than sodium silicate-containing ones in terms of setting, workability, and strength-gain performance. Addition of an admixture altered the setting time and workability of the mixes. The early-strength-gain property of the mixes also altered due to such admixtures.