Influence of Water, Alkali Activators, and Curing Regime on the Workability and Compressive Strength of the Alkali Activated Mortar


The effect of the water to fly ash (W/FA), alkali activators to fly ash (Alk/FA), and curing regimes on the workability and compressive strength of the alkali-activated mortar (AAM) was studied. Three high calcium fly ashes (FAs) having different chemical compositions were used. Sodium hydroxide (SH) and sodium silicate (SS) were used as the alkali activators. The two alkali activators were mixed together at ratio of 1.0. Two curing regimes, elevated heat curing in an electric oven at 70 oC for 24 hr and ambient curing at 23 ± 2 oC, were applied. The water to fly ash (W/FA) ratios were 0.350, 0.375, and 0.400. However, the alkali activators to fly ash (Alk/FA) ratios were 0.250, 0.275 and 0.300. The results revealed that the workability and the compressive strength of the oven cured specimens were decreased with increasing the calcium content of FA in the mixture. However, the compressive strength of the specimens that cured under the ambient temperature increased with increasing the calcium content. The workability increased with increasing the W/FA and decreasing the Alk/FA. The compressive strength based on both curing regimes decreased with increasing the W/FA. The optimum Alk/FA was 0.275 with W/FA of 0.400.

Meeting Name

20th IABSE Congress, New York City 2019: The Evolving Metropolis (2019: Sep. 4-6, New York City, NY)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Alkali activated mortar; Class C fly ash; Compressive strength; Sustainable materials; Workability

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2019 International Association for Bridge and Structural Engineering (IABSE), All rights reserved.

Publication Date

01 Sep 2019

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