Research On The Characteristics Of Humidity Field In The Early Age Of Concrete Structures Under Construction

During the construction of buildings,the next construction process is often carried out directly during the curing period.At this time,due to the influence of pressure and environment,the internal humidity field of concrete will change.It causes different degrees of cracks and damage in the concrete,which greatly reduces its durability,safety and practicability.Aiming at the characteristics of early age humidity field of concrete structures under construction,this thesis studies the basic theories of early age concrete humidity field and stress field,the wet mechanical coupling mechanism of early age concrete is studied by the combination of test and simulation.Theoretical research,the relative humidity measurement test of early-age concrete under the action of different ultimate load degrees was independently designed,and the relative humidity change law of early-age concrete under the influence of three factors,including ultimate load degree,curing age and depth from the surface,was studied.According to the test data and nonlinear fitting results,the load influence coefficient is proposed.Based on the load influence coefficient and the curing age,the formula of the humidity diffusion coefficient is modified,and the influence law of the load degree on the humidity diffusion coefficient of concrete at the early age is summarized.Experimental research,the relative humidity measurement test of early-age concrete under different ultimate load degrees was independently designed according to the national standard,and the relative humidity variation rule of early-age concrete under the influence of three factors: ultimate load degree,curing age and depth from the table was studied.According to the test data and nonlinear fitting results,the load influence coefficient is proposed.Based on the load influence coefficient and the curing age,the moisture diffusion coefficient formula is modified,and the influence law of the load degree on the moisture diffusion coefficient of concrete at early age is summarized.In terms of finite element analysis,based on the existing experiments,a wet-mechanical coupling model of early-age concrete was established through COMSOL software.By comparing with the original model,it is found that the simulated value is in good agreement with the experimental value,which verifies the accuracy and practicability of the modified humidity diffusion coefficient.At the same time,according to the simulation results,the humidity variation law of early-age concrete under the influence of load degree,curing age and depth from the table is obtained.