Effect Of Gel Particles On Curing Of Concrete And Mechanism Analysis

The moisture diffusion and self-drying of HPC reduce the internal relative humidity,and lead to the cracks caused by drying shrinkage,thus affecting the durability and strength of concrete.This phenomenon can be effectively avoided by curing in concrete.At present,there are three kinds of internal curing materials: porous lightweight aggregate,superabsorbent resin and shrinkage reducing agent.However,the three kinds of materials will bring some disadvantages to reduce the performance of concrete during the curing periodIn order to improve the early shrinkage and cracking phenomenon,the moisture content of concrete was changed by adding the curing material.As the dry shrinkage deformation of concrete is the result of the change of internal humidity,it is the premise and foundation to analyze the action of curing materials in concrete to understand the characteristics and distribution of humidity of concrete.The purpose of this unit is to test the effect of a new type of internal curing material by adding it into concrete,and then verify the regulating effect of the internal curing material on the internal humidity of concrete through the numerical model calculation and analysis of the humidity field.According to the basic principle of internal curing material,a new kind of gel particle was prepared.Through the test ratio,preparation method and performance measurement,the final prepared gel particles moisture content up to 85%,excellent water retention and water release performance.And it has hydrophobicity after it reacts to release water in concrete.Therefore,it is assumed that it plays a certain role in the humidity regulation of concrete in the internal curing test.Made by adding gel particles in curing of concrete specimens,in the process of the whole detection showed good changes in humidity,test in the concrete internal respectively set up the location of different distances away from the concrete dry surface,in order to detect internal humidity change regularity of different positions,according to the experimental results,the dry surface close to the location of the humidity lower rate higher than the distant place,adding gel particles inside the concrete moisture compared with not adding the experimental group,relative humidity within the 112 d age are promoted,before the age of 28 d humidity at different positions of appreciation to 28 d age as the cut-off point,Humidity increases by 2%-5% before and 9%-14% after 28 d.For the internal curing test,sem and X-ray diffraction were used for microscopic analysis to observe the changes of cement hydration products in its 56 d age.The hydration products can be directly analyzed.After the original water reaction was consumed,the gel particles released water to promote hydration reaction,and then effectively reduced drying shrinkage.In order to further verify the humidity regulating effect of gel particles,the humidity field model of concrete is calculated by MATLAB.Humidity field model is mainly composed of the drying model and diffusion model is established in this paper,the main calculation parameters for the degree of hydration and moisture diffusion coefficient,this paper analyses the moisture diffusion coefficient and humidity,temperature,water cement ratio and other factors,the relationship between,for calculating parameters are difficult to determine a combination of test and the European standard for parameter selection.Finally,the moisture value curve of each age calculated by the concrete humidity field model is basically consistent with the humidity value detected by the test,and the difference of humidity is controlled within 1%.Through the numerical simulation of concrete humidity field,it is verified that the gel particles as internal curing materials play a positive role in the change of the internal humidity of concrete.