Experimental Study On The Influence Of Environmental Temperature?Relative Humidity And Pore Structure On The Drying Shrinkage Of Concrete Brick

Drying shrinkage is one of the main factor causing cracking of concrete brick masonry wall,the main factor causing drying shrinkage of concrete brick including temperature,relative humidity,moisture content on the wall,curing age,brick size and internal pore structure,etc.This paper mainly studied the drying shrinkage of concrete brick under different environment temperature and relative humidity as well as the influence of the internal pore structure to the drying shrinkage of concrete brick.For the study of environmental temperature and relative humidity that affect the performance of the concrete brick drying shrinkage.This paper set I,II,III,IV,V,five different test environment,For each test environment should have different temperature and relative humidity conditions,and test the drying shrinkage of concrete brick under different test environment,the temperature of the environment I ~ V respectively set up to 30 ?,40 ?,50 ?,60 ? and 70 ?.Through the test obtained equilibrium moisture content and drying shrinkage law of concrete brick under different environment,the experimental results showed that with the temperature rise and the humidity decline,the lower the equilibrium moisture content,the shorter the time of arrival at equilibrium moisture content,the faster the drying shrinkage of concrete brick and the greater the drying shrinkage value.By the test data,according to the material adsorption theory,based on the revised OSWIN model,obtained the OSWIN model that adapt to concrete brick,and established the relationship between the equilibrium moisture content and drying shrinkage of concrete brick.This paper compared the difference of different drying shrinkage test standards at home and abroad in 5 respects such as the specimen size,the number of specimens,the specimen initial state and the test environment,the measuring method.In accordance with the GB/T2542,the AS/NZS 4456.12,the BS EN 772-14 trials on drying shrinkage of concrete brick,experiment results show that with the environment temperature rise the humidity decline,the faster the concrete brick water loss,the shorter the time needed for reach the equilibrium moisture content,equilibrium moisture content is lower,the faster the drying shrinkage,the value of drying shrinkage is bigger.Verify the OSWIN model of concrete brick and the relationship between the equilibrium moisture content and drying shrinkage valueunder different test environment can well predict the balance moisture content and drying shrinkage value of concrete brick values.Through single suction experiment of concrete brick A?B?C which made by different vibration stress on the same kind of raw material.Based on the water absorption kinetics theory measured the average pore radius of each brick.Accordance with the GB/T 2542 doing drying shrinkage test of A,B,C three kinds of pore structure concrete blocks.The test results show that to the concrete brick,the smaller the average pore radius,the drying speed is lower,the total drying shrinkage value is greater.Obtained the relationship between shrinkage value and the average pore radius when the brick got balance moisture state.The type shows that the smaller the average pore radius the greater the drying shrinkage value of concrete brick.Obtained the relationship between different pore structure of concrete brick drying shrinkage value and relative moisture content.Put forward the critical relative moisture content.Obtained the critical relative moisture content and the relation between the average pore radius of concrte brick.