Influence of Non Chloride Accelerator in Cement Concrete

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International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, (Print) 2319-1821 Volume 3, Issue 12 (December 2014), PP.24-32

Influence of Non Chloride Accelerator in Cement Concrete P.Kathirvel1 1

Assistant Professor, Department of Civil Engineering, Mahendra Institute of Engineering and Technology Namakkal, Tamilnadu, India

Abstract:- The present experimental work explains the combined effect of a commercial non-chloride hardening accelerator and method of curing in the strength development of concrete. Ordinary Portland cement (OPC) was used to produce concrete mixtures. Concrete mixtures were designed as per the guidelines of IS 10262:2009. Compressive strength of standard cube specimens (150 mm) at early and later- age, cured with water were studied. Performance of accelerator at a given age of concrete was assessed based on the maximum percentage increase in the compressive strength. The strength of control mix cured with water is taken as reference. Among various types of chemical admixtures, Non Chloride Accelerator Admixture (NCA) is chosen. The non chloride accelerator admixture is added with normal mix of the concrete in the nominal dosage and the effects are studied. 0.8%, 1.0%, 1.2% of non chloride accelerators were mixed with various grades of concrete such as M20& M25. The optimum level of high early development strength was analyzed. Average efficiency of the curing compound for the given age was calculated as the ratio of average compressive strength of concrete cured with NCA to that cured with water. The test results revealed that, the type of curing affected the optimum performance of accelerator in concrete mixtures. Average efficiency of the curing compound was found to be more at early- age of the concrete mixtures. Keywords:- Accelerator, OPC, Compressive, Flexural and Split Tensile Strength of Concrete.

I.

INTRODUCTION

Concrete is a composite construction material composed primarily of aggregate, cement, and water. In general the coarse aggregate used is broken granite stone and the fine aggregate used is river sand. The common Portland cement and other cementitious materials such as fly ash and slag cement, serve as a binder for the aggregate. Various chemical admixtures are also added to achieve varied properties. Water is then mixed with this dry composite, which enables it to be shaped and then solidified and hardened through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, eventually creating a robust stone-like material. Concrete has relatively high compressive strength, but much lower tensile strength Additives are shortly named as Admixtures. Admixtures interact chemically with the ingredients of the concrete and change its performance in the fresh and hardened state. They confirm special beneficial effect to concrete. They can enhance the workability of the fresh concrete. The dosage of mixing will be 0.8% to 1.5% by weight of cement. Research on the use of supplementary cementitious materials in cement concrete hints at the limitation of their blending with OPC at site due to lack of testing facility to check their pozzolanic characteristics and due to other practical reasons. Hence blending of cementitious materials during the production of cement under strict quality control is prudent to reap the benefits. 1.1 Accelerator Non-chloride accelerators are now being tried in place of calcium chloride in order to minimize potential of steel corrosion. Accelerators primarily target acuminate phase resulting in rapid workability loss. Limited Experimental study on the accelerators shows that they not only enhance rate of hydration but help in providing better paste quality and surface characteristics. It is also experimentally proven that as the curing age is increased from opening time to maturity, concrete with accelerating admixture showed better resistance to abrasion which is a desirable property for pavement concrete. 1.1.1 Reasons for Using Accelerating Admixture The major reasons for using accelerating admixtures are  To reduce the cost of concrete construction  To achieve certain properties in concrete more effectively than by other means  To maintain the quality of concrete during the stages of mixing, transporting, placing and curing in adverse weather condition.  To reduce shrinkage cracks in concrete.

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