Effect of Sulphate Attack on Self Compacting Concrete

Many current structures are characterized by the complexity of architecture (various shapes and bends) and a high concentration of reinforcement which often makes it difficult to use concrete with conventional plasticity. Recent researches have been conducted in order to adopt concrete to these structures. The resulting concrete formulations are characterized by better workability, while remaining stable with mechanical properties and durability. This new type of concrete can fit in place under the influence of gravity, hence the term self compacting concrete “SCC”. The external attack of sulphate salts is considered as one of the major problems affecting concrete durability. Sulphates are highly soluble salts in the form of sodium sulphate, calcium sulphate, potassium sulphate, and magnesium sulphate. Sulphate attack is a process in which sulphates react with various phases of hydrated cement paste leading to deterioration of the concrete matrix through spalling, softening, and mass loss, which may lead to expansion and loose strength and elasticity. It is recognized as a complex process due to the effect of The aim of this study to demonstrate the change in strength in SCC when the cement is replaced with lime powder and to determine the sulphate attack on the self compacting concrete. Compressive strength characteristics for 7days and 28days of the self compacting concrete are determined in which cement is partially replaced with lime powder (0%, 10%, 20%, 30%, 40%) and cured in the sodium sulphate solution. To attain the planned objectives of the present investigation, M20 grade self compacting concrete is taken and values of cement replaced with  limestone at the percentages of 0%,10%,20%,30% were considered. The total of 48 cubes,48 cylinders were casted.24 cubes and 24 cylinders are cured in normal water and 24 cubes and 24 cylinders are cured in sodium sulphate solution. and determined the compressive strength and split tensile strength  values. The developments of compressive and tensile strengths of self compacting concrete at the age of 7and 28 days are investigated. Under the influence of external sulphate attack. The parameters comparing the SCC with normal concrete are increased at the 20% of lime powder replacement after that the parameters decreases gradually.