DURABILITY OF CONCRETE IN ACIDIC SOILS AND WATERS

Abstract

This article reviews current recommendations for the type of concrete suitable for use in acidic conditions, expecially in contact with acidic groundwater, and the limited data on concrete performance available. Types of acidic waters are first described (ie waters containing mineral acids, humic acids or carbolic acids). Factors controlling the rate of attack on concrete by such acidity are also discussed. It is the rate of penetration of the acid which will govern the durability of the concrete and the chief factors to consider are: a) chemical factors such as type of acid and its ph, the cementitious binder and the type of aggregate; B) physical factors relating to the composition of the concrete and the type of exposure. For example, the existence of a head of water on one side of the concrete or movement of water over the concrete surface; c) soil type and permeability; d) goundwater. Tables giving requirements for concrete exposed to: i) sulphate, II) acidic water; and III) attack from acids of ph greater than 2.5 are provided as is a table setting out the French standard for concrete in acid and sulphate groundwaters. A procedure for the classification of acid soils and waters is also suggested.