The influence of chloride ion diffusion on the structure of cement composites containing carbonate additives

Abstract

One way to reduce the diffusion of chlorides deep into concrete is to bind chlorine ions into stable hydration products. It is known that systems containing carbonates have an increased binding capacity towards chlorides. The goal of this work is to study the effect of carbonate additives on the depth of diffusion of chlorine ions in cement composites (mortars). As controls, samples of mortar were made using cement CEM I 42.5 R as binder. In the main samples, 15% of cement was replaced by carbonates - chalk and limestone. The strength characteristics of mortar samples kept in water and in a sodium chloride solution were studied. According to test data, it was established that the compressive strength of samples with the addition of chalk or limestone practically does not change under the influence of a chloride solution. The compressive strength of samples without additives in the salt solution decreased by 8%. The depth of diffusion of chlorine ions deep into cement composites was also studied. It has been established that replacing part of the binder with carbonate additives does not reduce the permeability of porous cement composites for chloride ions.