Influence of superplasticizer on workability and strength of ambient cured alkali activated mortar
Elsa Paul
Abstract
Alkali activated materials contain aluminosilicates, which can be used for building with a low environmental impact by repurposing waste resulting in cost-effective construction. The impact of nature and superplasticizer dosage on fly ash slag-based ambient cured mortar activated with sodium silicate and sodium hydroxide is not yet definitive. This paper studies the influence of various superplasticizers on fly ash-based ambient cured mortar activated with sodium silicate and sodium hydroxide. The effect of superplasticizers was evaluated by adding various superplasticizers including melamine, polycarboxylate ether and naphthalene-based superplasticizers in different dosages from 0 to 3% at 0.5% intervals. Fresh properties of alkali-activated mortar with various percentages of superplasticizer were tested using flow table apparatus and compared with mortar without superplasticizer. The hardened property of the alkali-activated mortar was tested by checking the compressive strength of the mortar cube. From the test results, naphthalene and polycarboxylate ether-based superplasticizers are compliant with alkali-activated mortar. Melamine-based superplasticizer shows a slight reduction on strength of alkali-activated mortar. In the ambient cured mortar, the optimum concentration for naphthalene and polycarboxylate ether-based superplasticizers is 2.0 percent, whereas melamine-based superplasticizer exhibits maximum strength for 2.5 percent. Even though naphthalene and polycarboxylate-based superplasticizers are effective for alkali-activated mortar, the most efficient type is the polycarboxylate ether-based superplasticizer.