A critical review on the factors influencing the design of test methods for assessing acid attack in concrete

Abstract

Abstract Concrete being alkaline in nature is highly vulnerable to acidic environment. When concrete is exposed to industrial effluents, the acids in these effluents alter the chemical equilibrium of cement matrix resulting in microstructural deterioration. Currently, there are no standard procedures for assessing the performance of concrete subjected to acid attack. In order to develop such test methods, explicit knowledge about the factors influencing test method for assessing the acid attack is imperative. This paper outlines the need to develop such test methods and also classifies the factors influencing the selection of test methods as test condition related factors, specimen related factors and acid related factors. Test condition related factors comprises of the testing environment adopted for the study. The test should simulate the actual conditions and type of attack expected to occur at the field, which can be achieved through replenishment of acid solution, alternate wetting and drying, abrasion etc. Specimen related factors deal with the physical properties of the specimen used whereas the acid related factors include various aspects of acid chosen for the study other than its material properties. As the surface area to volume ratio of the specimen increases, more surface area is exposed to the chemical attack, which hastens the rate of deterioration. Also, the ratio of volume of acid solution to specimen enhances rate of concrete degradation. Hence, many factors together have to be considered and studied properly while designing a test method for assessing acid attack.