Durability of cement-based and geopolymer coating mortars in the Persian Gulf simulated environment

Document Type : Research Article

Authors

1 Concrete Technology and Durability Research Center, Faculty of Civil Engineering, Amirkabir University of Technology, Tehran, Iran.

2 construction management- Faculty of Civil Engineering-Amirkabir University of Technology- Tehran- Iran

Abstract

Due to the importance of coastal structures and the existence of destructive environmental conditions near the shores, the maintenance of these structures is more important. One of the ways to maintain such structures is to apply a protective coating layer of mortar. In recent years, due to the importance of environmental impacts and also in order to reduce energy consumption, geopolymer mortars have been considered as an appropriate alternative. Geopolymers are inorganic aluminosilicate compounds in which instead of cement, a matrix of aluminosilicate materials, which is activated by alkaline activators, plays the role of cement paste in the mortar.

In this research, mechanical properties and durability of 6 mortar mix designs, including 4 cement-based mortar mixtures containing supplementary cementitious materials and 2 geopolymer mortar combinations with slag and silica fume that cured in the simulated Persian Gulf environment has been compared. To compare the mechanical properties, compressive strength, tensile strength, and drying shrinkage tests were conducted. Also, the capillary water absorption, water penetration under pressure, and rapid chloride migration tests are performed to evaluate the durability.

The results of this study display that ternary cement-based mortar that has higher amounts of SCMs is a better choice than binary cement-based mortars and geopolymer repair mortars for repairing damaged concrete structures in coastal areas. Among other mixtures, the geopolymer mixture with potassium hydroxide as an alkaline activator and the cement-based mixture with a replacement of 7.5% by weight of silica fume can be introduced as suitable materials for repairing marine structures.

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