Research On Fly Ash Concrete Tensile Properties And Size Effect

The direct tensile strength is one of the important parameters of the mechanical performance of concrete, it is of great significance to concrete crack resistance, durability, but due to the complexity of existing direct tensile test method and test difficulty is high, usually used in engineering splitting strength, flexural strength, instead of the axis tensile strength, but the experiment proved that splitting strength and flexural strength is the in direct tension of concrete, and can’t reflect the direct tension of concrete, the test values higher than the real axis tensile strength of concrete, lead to project risk.In addition, the fly ash has become a necessary component of today’s concrete admixture, fly ash concrete has been used in the field of building engineering, it’s meaningful to study the fly ash to the influence of direct tensile strength of concrete and three kinds of relationships between tensile strength. At the same time, the current building structure gradually towards long-span field development, the influence of size effect increasingly obvious, the influence of size of fly ash concrete is also need to study.So this article detailed study of the problems in the following aspects:1. Experiment study on direct tensile strength of concrete specimen.(1)Designed and developed the three concrete direct tensile test mould and form a complete set of loading device, through the comparison of three methods of direct tensile test results, find out a simple and accurate direct tensile test method;(2)For the direct tension strength of middle embedded rebar, size of embedded rebar exposed of will affect the strength of direct tension strength, design of experiment for four different the size of exposed steel about the specimen, by analyzing the results of experiment, find out the optimal size steel exposed;(3)With fly ash replacement ratio, concrete strength grade as the independent variable of standard size specimens for axial tensile test specimens and the corresponding splitting test, Flexural test, compression test, study the influence of fly ash replacement rate and concrete strength grade to the tensile strength,and the intensity of the conversion relationship between;(4)With the section size,fly ash replacement ratio and concrete strength grade as the independent variable of standard size specimens for axial tensile test specimens and the corresponding splitting test, Flexural test, compression test, study the size effect of fly ash concrete tensile strength;2. Experiment study on direct tensile properties of reinforced concrete component.(1)The test of large size reinforced concrete direct tensile component test was carried out,to study the effect of the cross section size,fly ash replacement rate,longitudinal reinforcement ratio to the tensile stress-strain curve of concrete and related feature points.Based on the experimental basis, and through the performance and the size effect of fly ash concrete tensile test research, not only help to understand the influence of fly ash and size to tensile properties, as well as provide data support and reference to the tensile strength of fly ash concrete used in building structures and research scholars in related field.