Experimental Study On Mechanical Behavior Of C40Concrete At Early Age

In the construction of concrete structures, the strength of concrete at early age has an important impact on the safety of structure during the construction, and becomes the decisive factor of the structural safety and restricting factor of project progress generally. While the concrete strength with the increase of time has a development process and it’s difficult to be controlled in the construction period. In general, we use the material performance indexes of28d as the performance indexes of concrete, while in practical engineering, the curing time of concrete cannot be guaranteed due to speed up the pace of construction. Therefore, studying on the mechanical properties of concrete at early age has important theoretical meaning and engineering application value. The article is based on the experiments of C40commercial concrete at early age, and has studied the mechanical properties and its changes with time. The article mainly completed the following works:1. Experiments were conducted on the blocks of C40commercial concrete, which include the cube compressive strength test, axial compressive strength test, splitting tensile strength test, static elastic modulus test, test of uniaxial stress-strain curves and biaxial compressive curves test. The development law of these mechanical performance indexes has been studied in the article. According to the comparison with other experimental data, the compressive strength of concrete at early age is related to the temperature and additive agent.2. Based on the experiments, the article studys the scheme of uniaxial compressed stress-strain curve of C40commercial concrete, concludes the uniaxial compressed stress-strain curve and deduces the reasonable stress-strain curve equation and the constitutive relation model. With the deduced constitutive relation model of C40commercial concrete, the article uses the finite element analysis software ABAQUS imitate uniaxial compression of prism test blocks and concludes its uniaxial compressed stress-strain curve, which fits well with the curve which getting from the experiments.3. Based on the experiments, the article studys the scheme of biaxial compressed stress-strain curve of C40commercial concrete, concludes the biaxial compressed stress-strain curve, observes the characteristics of the biaxial compression curve, draws the compression concrete under biaxial failure envelope and peak strain envelope and concludes the biaxial compression strength failure criterion, which fits well with the curve which getting from the experiments.