Method for determining modulus of elasticity of plastic concrete

Abstract

The invention discloses a method for determining modulus of elasticity of plastic concrete. 3 150x150x300mm prism testing pieces are manufactured under industrial standards, the testing pieces to be measured are placed on a testing machine and starting reading is recorded, the testing machine is started, deformation values under various loads are recorded, and static compressive modulus of elasticity of the testing pieces are calculated in accordance with the following equation Ec = (P1/A) x (L/deltaL), wherein L is the full length of the testing pieces. The average value of the static compressive modulus of elasticity of the three testing pieces is regarded as the testing result. The method fills in the blank in the aspect of plastic concrete testing method, is characterized by adopting full gauge length for measuring the testing pieces, avoiding pre-pressing procedure and taking the slope of 40% secant as the elastic modulus value of the plastic concrete, and simultaneously eliminates 0.5MPa of stress and the calculation of stress items thereof from the calculation of the testing result, thereby overcoming the defect of large error in the prior method, achieving simpler and faster testing process and being advantageous for the popularization of the method.

Description

technical field [0001] The invention belongs to the technical field of water conservancy and hydropower construction, in particular to a test method for measuring the elastic modulus of plastic concrete in the construction of cut-off walls Background technique [0002] Plastic concrete refers to the compressive strength ranging from 1 to 5 MPa, the elastic modulus of 300 to 2000 MPa, and the permeability coefficient of n×10 -6 ~n×10 -8 , and has a large fluidity of underwater concrete, which is mostly used in the cut-off wall structure of earth-rock dams. Because the amount of cement used in the mix ratio is less, more bentonite and clay are mixed, and water reducing agent and air-entraining agent are added to improve its impermeability, therefore, plastic concrete has low strength and certain impermeability. A special type of concrete with low elastic modulus and large strain. Compared with ordinary underwater concrete (the compressive strength is 15-35MPa, the elastic m...

AI Technical Summary

Problems solved by technology

This method is mainly aimed at nearly rigid ordinary concrete, but for plastic concrete, there are obviously unreasonable places

For example, in the existing elastic modulus test method, it is required to preload the concrete specimen for three times or more, and then conduct a formal test, the purpose of which is to eliminate the residual deformation that cannot be recovered in the concrete, which is very important for ordinary concrete It is necessary, but it may not be suitable for plastic concrete with large deformation; secondly, in the calculation formula of elastic modulus, it is stipulated that the stress value of the dividend is the difference between the stress of the failure load of 0.4 minus the stress of 0.5MPa, and the strain value of the divisor It is also the difference between the strain of the failure load of 0.4 minus the stress of 0.5MPa and the strain

Images