An Optimal Accelerator Used In Concrete

فاقد چكيده فارسي

It has long been known that curing concrete during cold weather can result in an inferior product with substandard properties. Curing also takes much longer, adding to job costs and extending the time before the concrete surface can be used. Admixtures are those ingredients in concrete other than portland cement, water, and aggregates that are added to the mixture immediately before or during mixing. An accelerating admixture is used to accelerate the rate of hydration (setting) and the strength development of concrete at an early age. Calcium chloride (CaCl2) is the chemical most commonly used as accelerating admixture, especially for nonreinforced concrete but it results in corrosion and lack of concrete durability; In order to solve these problems Aluminum hydroxide (Al(OH)3)and Aluminum Sulfate (Al2(SO4)3) were used. In this study, a total of 252 specimens in which different amounts of calcium chloride, aluminum hydroxide ,and Aluminum Sulfate were added to concrete were made. The effect of calcium chloride and aluminum hydroxide and Aluminum Sulfate on setting time, compressive strength, hydration temperature and permeability was determined. The specimens were experimented on in different days from 2 to 90 in order to measure strength. As a conclusion Calcium chloride causes a shorter setting time and lowers costs in comparison to Aluminum hydroxide and Aluminum Sulfate. On the contrary Aluminum hydroxide and Aluminum Sulfate have no effects on corrosion and they reduce the weight of concrete, prevent alkali reactions of aggregates, and increase durability.