Study On The Reasons Of The Rapid Slump Loss And The Improving Measures

The cement made from Jidong clinker has high strength both in early stage and late stage, but the concrete slump loss is very rapid, especially when the superplasticizer is added in. Therefore, the cement can hardly be used in HPC. The aim of this study is to find the reasons of the rapid slump loss and to seek some feasible measures to improve the slump loss.The XRD patterns show that there are no obvious differences between Jidong clinker and Qixin clinker, and what are the same be shown from the data of chemical compositions and mineral compositions. But the SEM photos indicate that there are some prominent distinction in the aluminate minerals between Jidong clinker and Qixin clinker, which result in the higher hydration reaction rate of Jidong cement than that of Qixin cement in the initial stage, thus more free water is converted into chemically boned water and physically absorbed water, and more free-water is closed in the flocculent structures. All above lead to the free-water that contributes to the fluidity decreases more of Jidong cement than that of Qixin cement. The reduction of the free water that contributes to the fluidity leads the rapid slump loss. The quantity of the water that exists in different state is calculated by the mathematical models, thus the slump loss can be estimated in quantity.Various factors, which have the effect on the fluidity, are examined. The cement composition with lesser fluidity loss is put forward. The experiment results indicate that without changing the clinker compositions, the slump loss can be controlled only by adjusting the amount and the type of gypsum, mixtures, the soluble alkali and the organic additions and the cement fineness etc. In the other hand there are no disadvantages to the other cement physical properties.