Effect of Accelerating Admixture on Properties of Concrete

Abstract

The problems of cold weather concreting arise from the action of frost on fresh concrete. If the wet concrete is allowed to freeze, the mixing water converts to ice and there is an increase in overall volume of concrete. Since there is now no water available for chemical reactions, setting and hardening of concrete are delayed. In this paper, the issue of delayed setting and hardening of concrete are addressed by the use of accelerating admixture(Sodium Nitrite) in concrete. Sodium Nitrite as accelerating admixture was added in five samples having Sodium Nitrite dosage of 1%, 1.5%, 2%, 2.5% and 3% by weight of cement. The concrete specimens were tested for 3 day, 7 day and 28 day compressive strength, flexural strength and splitting tensile strength and the results obtained were compared with those of normal concrete. The optimum percentage of accelerator that could be used without harming the properties of concrete was also assessed. The results concluded permissibility of using accelerating admixture(Sodium Nitrite) up to 2.5% by weight of cement and also the optimum percentage of accelerating admixture was found to be 2.5% with value of compressive strength, flexural strength and splitting tensile strength being maximum at the age of 3 days and 7days.