Comparative Study On Mechanical Properties Of Fly Ash Concrete Based On Uniaxial Tensile Test

Currently, the research for mechanical properties of fly ash concrete is not comprehensive enough, especially for the study on uniaxial tensile resistance performance of fly ash concrete is few, To this end, this article on the fly ash concrete under standard curing conditions and outdoor environment maintenance conditions, the law of compressive strength, splitting, axial tensile strength of fly ash concrete and the tensile elastic modulus of fly ash concrete were studied, to provide the corresponding basis for the application of fly ash concrete in the actual structure.Seven ages of concrete axial tensile, split tensile and cube compressive tests were carried out to get the relationship between tensile strength and splitting tensile strength of concrete under standard conditions, tensile elastic modulus of fly ash concrete was obtained by axial tension test. Drill core and rebound test for 4 ages under outdoor conditions, combination with cube compressive test under the condition of standard curing, comprehensive evaluation of compressive strength of fly ash concrete. This is not only beneficial to the improvement of the mechanical properties of fly ash, but also can provide the corresponding basis for the application of fly ash concrete in engineering.Due to the low precision of the axial tensile strength test results, the accuracy of the results is low, the tensile strength of concrete is mostly detected by splitting tensile test, about to axial tensile test of fly ash concrete, in this paper, the axial tension test method is used to solve this problem, the testing instrument is easy to make, fixture stiffness is large and can be reused and the operation is simple, there is almost no eccentricity in the axial tension test, the accuracy of the test results is guaranteed.The main conclusions are as follows:(1) Test results show that the compressive strength and splitting tensile strength of fly ash concrete basically maintain the rate of synchronous growth, and the ratio of the two is quite stable. and the ratio is between 1/10 and 1/13.(2) The splitting tensile strength and uniaxial tensile strength of fly ash concrete are basically consistent with the growth trend of age, the ratio of the two is stable, and the ratio is between 0.65 and 0.74.(3) The compressive modulus of elasticity and the elastic modulus of concrete increase with the age of concrete. the tensile modulus of concrete at early age is lower than the compressive elastic modulus, in the age of concrete 7d～91d, the tensile modulus of concrete increases faster than the compressive modulus of elasticity, and the ratio of the two eventually tends to 1:1.