Sodium sulfate and alternative combined sulfate/chloride action on ordinary and self-consolidating PLC-based concretes

An experimental investigation was carried out to assess the durability of self-consolidating concretes (SCCs) and ordinary concretes (OCs) under sodium sulfate and sodium sulfate/sodium chloride combined solutions. A wet/drying procedure was carried out for the two immersion modes, but in the second, sulfate and chloride were applied in an alternative way. The study variables were concrete type, mineral admixture nature, limestone filler (LF) or silica fume (SF), and W/C ratio ranges, 0.8, 0.5, and 0.3. Ordinary Portland limestone concrete samples were named OC0.8, OC0.5, OC0.3LF, and OC0.3SF. Six SCC formulations were prepared SC0.8LF, SC0.8SF, SC0.5LF, SC0.5SF, SC0.3LF, and SC0.3SF. Concrete samples were tested for compressive strength at 3, 14, 28, and 90 days; water sorptivity, mass change; Chloride penetration depth of concrete samples in the combined solutions; and SEM observations of high W/C samples. The results show that W/C and SF amount are the two main parameters influencing concrete performance; SCCs have better behavior than OCs in the applied tests; the influence of chloride on sulfate extent is found to be more significant for concrete having high and middle W/C; SEM monographs of high W/C concrete samples illustrate the formation of ettringite, gypsum and Friedel's salt.