Determination. Empty Cylinder Apparatus Of Fresh Self-compacting Concrete Rheological Properties

Self-compacting concrete is also called self-leveling concrete. The new reinforced concrete which at low water binder ratio has high mobility and isolation, not bleeding, can not rely on gravity flow by vibration level and filled with templates and parcel. so far,This new material have already started using self-compacting concrete in Japan, Germany, Britain, the United States and Canada, which is expected in countries water conservancy, transportation, mining, construction and other engineering structures with a wide range of applications. One of the key technological issues are:(1) self-compacting concrete rheological model; (2) the new mixing angle of self-compacting concrete on SCC rheological properties among the work of the various components of the interaction and the mechanism and test methods numerical simulation. Over the years, people have been exploring simple and accurate determination of the rheological properties test methods, but so far there are no generally acceptable standards or specifications or the formation of the scientific method. Therefore, the study not only easy to use to develop a practical, but also more scientific and reflect the rheological properties of concrete testing equipment and test method has very important practical significance.In this paper, the research data has been based on the innovation of the test method, which uses vertical continuous loading method; at the same time, remoter were also innovative design, using leverage, air cylinder apparatus sidewall (the empty cylinder apparatus Law). Combination with mechanical analysis, to determination the fresh self-compacting concrete rheological properties (shear stress and shear rate relationship). The specific work of the following:(1) The feasible of new remoter (including hammer test apparatus test cylinder, air cylinder apparatus test) to determination the rheological properties of fresh self-compacting concrete.(2) Determine the size of the new remoter,load volume and the amount of such classification, and the formation of the relative standard method.(3) To determine the different intensities of the fresh self-compacting concrete rheological constitutive model with new remoter.(4) According to the test by the discrete element theory (that PFC particles streaming software) on the work of testing fresh concrete test (slump test) carried out simulation calculation.Through the research the following conclusions:(1) The feasibility study of new remoter equipment including:improved hammer test as dynamic acceleration sensors can not measure the heavy hammer of fresh self-compacting concrete in the process of acceleration of change in motion failed; cylinder apparatus tests are based on certain assumptions premise down determine the cylinder wall friction (shear stress) and the bottom resistance (positive stress) the size, it is difficult to determine the compatibility of assumptions with the actual situation; However, based on the above two tests failed to improve the basis of lessons learned, after a reasonable trial computing and data analysis to improve the air cylinder apparatus testing technology is relatively feasible.(2) With a number of assumptions based on the use of force and reaction force and mechanical equilibrium theory of test data processing, combined with mathematical tools MATLAB7.1 in the Curve Fitting Toolbox CFTOOL on the rheological properties of fresh SCC values to be to yield the flow of fresh self-compacting concrete constitutive model; and domestic and foreign literature [46,47] obtained fresh self-compacting concrete rheological model to compare the results to determine the fresh determination of rheological properties of self-compacting concrete The new test method, the new test equipment. The new test method, that is, vertical continuous loading method (the use of leverage, for five consecutive mass loaded); new test equipment, is air cylinder apparatus sidewall friction law (the empty cylinder apparatus method).(3) C30, C40, C60SCC analyst:fresh self-compacting concrete instantaneous shear stress and shear strain rate is linear, that is the instantaneous fresh concrete shear stress with shear strain rate increases with the increase of Shear speed reduction should be reduced. Fresh self-compacting concrete with increased strength, its yield stress decreased slightly, while the plastic viscosity coefficient was increased. Fresh self-compacting concrete between the yield stress in the 70-120Pa, plastic viscosity coefficient within the 100-180Pa·s, while the fitting error and testing error of less than 10%.(4) Theory of particle flow numerical simulation of the specimen is a continuously changing, and debugging of the micro-mechanics parameters (including particle size) process. Based on discrete element theory slump test of fresh SCC simulation results show that:select the maximum particle size of 5 times the smallest size, choose the smallest particle size was 0.2cm, the simulation results more reasonable.