The effect of over dosage of concrete retarder daratard 40 in concrete

Abstract

More than 70 % of insitu concrete is produced now by the ready mixed concrete industry in Malaysia. With the increases in economic growth and demand for highrise buildings as well as infrastructures make the industry to determine its own standards of the production by trial mixed design. The issues involves in the properties of fresh concrete during the casting stage. A high degree of workability is planned to speed up the construction. The suitable concrete retarder is being used in the fresh concrete to avoid the formation of cold joint due to time needed to place a large volume of concrete in a continuous operation. The chances to over dosage the concrete with retarder become so great and critical at the construction site. Sometimes it takes 2 to 3 days for the concrete to set and harden. It creates many doubt and disputes to engineers in the industries about the strength and durability of the concrete in long run. The study of behavior of the concrete with different dosage of retarder Daratard 40 has been conducted in the lab test prior to practical concrete practice. The investigation may help the industry to achieve the optimum dosage of concrete retarder without compromising the concrete strength. The relationships between slump test and optimum dosage of the Daratard 40 concrete retarder has been established from the study. Slump test a cheap, suitable and more reliable testing method use to detect the cause of over dosage in fresh concrete consent on consistency before placing and compaction works at the site