Study On Rheological Properties And Rheological Parameters Predict Of Cement Mortar

High-performance is the target of concrete which people is looking for all the time. High-performance of concrete should consist of the workability of fresh concrete, and the mechanics of harden concrete and durability. The workability of fresh concrete in the earlier effects the development of strength and durability. And then, the workability of concrete becomes more and more important.The workability of concrete affected on its rheological properties,and people enter on study of the rheological properties of concrete. Because of the effect of coarse aggregates, it is not easy to measure the rheological characteristic of concrete. Therefore people start to research the rheology of cement paste. But it is a great difference between concrete and cement paste, because cement paste has no aggregate. On the constituent and structure, mortar can look as the transition of cement paste and concrete. To some extent, mortar is closer to concrete and it can be known as fine aggregate concrete. Therefore, this study is base on the rheological properties of fresh cement mortar. Rotation viscometer is used to measure the rheological parameters. The rheological curves of mortar with superplasticizer and mineral admixtures or in different water-cement ratio, sand-cement ratio and temperature were measured and the rheological parameters are calculated. The theories on the rheological properties are analyzed. The result will instruct us to design the material from the study on the rheological properties of mortar。The result shows that:①When the other condition is same, the plastic viscosity, yield stress and thixotropy of mortar are bigger than cement paste. Because fine aggregates expend some free water to wet themselves, and there are more particles and the friction between the particles increases,there increase the resistance of mortar.②Temperature affects the plastic viscosity, yield stress and thixotropy of fresh mortar. The rheological parameters decrease with temperature in some sort. Temperature has a great affect to the rheological parameter changed with time, the higher temperature is, the faster plastic viscosity, yield stress grow.③Mineral admixtures can change the rheological properties of mortar. Fly ash can make the plastic viscosity increase, and yield stress decrease. The plastic viscosity and yield stress of mortar with slag are smaller than the mortar without mineral admixture. Silica fume increases the plastic viscosity and yield stress of mortar. The postponement, particle grade and sorption of mineral admixtures can improve the loss of rheological properties of mortar with time.④The plastic viscosity of mortar increases with dosage of fly ash, and the yield stress decreased at first, and then it increases. The finer fly ash is, the more effective it is. The plastic viscosity and yield stress of mrtar decrease with dosage of slag at first, and then increase, the minimum dosage of slag is in 30%. The two rheological parameters of mortar increase with silica fume dosage.There are some relationship between material mixtures and the rheological parameters. Forecasting the rheological parameters of mortar using the Artificial Neural Networks is advanced. This paper introduces the theory ANN and BP ANN. Then using BP ANN to network train 16 mortars from orthogonal experiment, it studies the non-linearity rules. And then it simulated the new samples. The nicety of results is beyond 90%. The way using BP ANN is availability.