Researches Of RCC Super Retarding Compound Additive

In connection with the design requirements and construction conditions of the Linhekou RCC arch dam, a new type super retarding compound additive is developed on the basis of study on retarding compound additive applications in RCC. This new type of additive can meet the requirements of retarding time, water-reducing effect and other various performance indexes, including the initial setting time 18~26h, water-reducing rate >20%, and VC value 5~8s. Through the mechanism of cement hydrating rate, the effects of super retarding compound additive on RCC initial setting time and the mixture's mechanic property are studied and extensive tests are carried out in laboratory and field on RCC. Firstly, adjusting tests are carried out according to the construction requirements for RCC retarding time in different seasons and a super retarding compound additive suitable for different season and temperature conditions is developed. And then composite proportion tests are carried out on retarded components and optimalhigh efficient water reducing agent and the formulae of super retarding compound additive is determined. Based on the test results, relevant parameter tests are respectively conducted in the Material Lab. of NIDRI and the construction site of Linhekou, and the additive has good effects and its quality is stable. This study is proved to have practical significance for the construction of the Linhekou RCC arch dam and Test methods can be a useful reference for RCC mix design and material selection with retarating compound additive of other RCC dams.