Effect of Curing Temperature on Crack Resistance of Low-Heat Portland Cement Hydraulic Lining Concrete

In this paper, standard maintenance and simulated field actual temperature maintenance are carried out. The compressive strength, splitting tensile strength, axial tensile strength, elastic modulus and its growth rate were tested. It is found that temperature has a great influence on the mechanical properties of concrete. Among them, temperature has the greatest influence on splitting tensile strength. The numerical difference of this test is within the acceptable range. It shows that the research in the laboratory has a good reference significance for the actual situation in the field. Based on the N-S maturity formula, F-P equivalent age formula and D-L equivalent age formula proposed by maturity theory, the maturity indexes under two curing conditions are calculated. The development law between strength and maturity is studied by fitting logarithmic function, exponential function and hyperbolic function with fitting software. It is concluded that the strength of low heat Portland cement concrete increases with the increase of maturity under quasi environmental curing and standard curing. The fitting accuracy of hyperbolic function in F-P equivalent age and D-L equivalent age is the highest. XRD was used to analyse the phase of low heat cement. Hydration products and microstructure of low heat cement with 25 % fly ash were analysed by SEM. Energy spectrum analysis of element content. The results showed:The late low heat cement cementitious system has a certain amount of Ca(OH)2. Good compactness, Ensure the later strength development of concrete. It has micro-expansion effect, It has good effect on long-term crack resistance of hydraulic lining structure.