Evaluation of pozzolanic mortars containing micro silica against acid and chloride attack

Acidic environments lead to rapid destruction in the reinforcement concrete structures. Chloride ions also lead to rebar corrosion. The aim of this study is to represent an appropriate mortar which resists against each of the acidic and chloride attack. For this purpose, three types of cement with combination of pozzolans (micro silica and pumice/trass) were used as 10 mix designs. Experiments consisted of compressive strength, capillary absorption and water permeability as general tests, and tests which control the performance of specimens against acid attack (compressive strength reduction, weight loss) and chloride attack (surface electrical resistivity, rapid chloride migration test). Results showed that until the age of 240 days, combination of 5% micro silica and 8% trass in slag cement would be an appropriate mix design for mortar against both chloride and acid attack. Usage of 10% pumice as a substitution of trass in the mentioned mix design performed well too.