| Concrete is a kind of artificial stone, which is made by hardening the mixture of cementing material, water and coarse, fine aggregate with the proper proportion for a certain period. At present, high-performance concrete is increasingly being used in civil engineering construction, modern concrete has high-performance, which is the necessary conditions for the performance of hardening concrete. Liquidity is an important indicator of the performance, which refers to the behavior of the mixing of concrete undering the gravity or mechanical vibration. The level of liquidity ,that has a direct impact on construction of the difficulty and the quality of concrete, indicates the consistency of the mixture. In the today's concrete projects, the liquidity of concrete, particularly the liquidity of slurry in the concrete, has aroused people's great attention. The theoretical research in cement-based materials rheological properties and engineering practice guidance are also increasingly attract people's attention, for the increasing number of the filling materials and the repair materials in special projects.At present, there are two major ways for the research of this topic. One is the flow method, that take testing methods such as concrete slump, micro-slump, the funnel, cement paste consistency, Weibo consistency for representatives. Another is rheologic testing methods. There is a certain one-sidedness in the flow of the flow method. They can not fully reflect the performance of mortar, and rheological research methods are a more comprehensive evaluation of the performance of cement mortar.Factors of water-cement ratio, mineral admixture content, the amount of additives, cement varieties, aggregate characteristics, aggregate-cement paste ratio, other additives, construction, environmental factors all have impact on the rheological properties of cement mortar and have different levels of impact on concrete rheological properties.Based on the basic principles of rheology, in accordance with rheological parameters of the yield stress(τ0), coefficient of viscosity(η),expansion of the mortar (fluidity) and the expansion velocity (speed mobile) were used to reflect the mobile performance mortar in this paper. The concrete mixture was studied according to their characteristics as the flow of Bingham (rheological equation:τ=τ0 +ηγ)or similar characteristics of a Bingham. According to the relevant national norms and test in this paper, useful conclusions have been brought forward:1,Testing methods and the pilot programme in this paper are feasible, as scientific and rational results and conclusions can be drawn from the pilot programme. Methods in this paper can reflect the mortar rheological properties more convenient and comprehensive than methods in some of the traditional research programme.2,As the greatest impact factors on the flow of cement mortar, the increase of water-cement ratio can arouse greatly increase in the fluidity and speed of flow. However, blindly increase water-cement ratio of the other mortar would cause adverse effects to other property of mortar. And the fly ash can significantly improve the flow of cement mortar. The rules changes inapparent when dosage of fly ash is more than 20%. The flow of cement mortar can not be improved by adulterating slag alone. The experiment showed that the viscosity of the cement paste increased and the speed of flow decreased with the increment of percentage slag composition (not more than 25%).The redispersion emulsid powder can improve the flow of cement mortar and there would be secrete-water later.There is super water-reducing agent in the redispersion emulsid powder, and the effect in this test is obvious for they work together.3,Dosage of mineral admixture as slag, redispersion emulsid powder and fly ash were researched respectively. The segregation bleed and secrete-water would appear when admixing mineral powder after waste rubber powder, and would be more serious with increasing waste rubber powder. The segregation bleed and secrete-water will not happen with the waste rubber powder and fly ash double-doped. The segregation bleed and secrete-water phenomenon will improve with admixture use of slag and fly ash. The study also found that mineral admixture with the same content, fly ash mortar improve the overall mobility of the best, the improvement of slag weak, admixture between the effect of the improvement between the slag and fly ash. From the point of the improve of the mortar flow speed, with the amount of powder in the same circumstances, the overall trend is the slag > fly ash> admixture.Based on the conclusions above, recommendations were made in this article, and take self-leveling mortar and plastering mortar for example, appropriate rheological properties should be made in the project events, depending on the circumstances to adjust the proportion of mortar component, then meet the functional requirements of certain environment.
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