Study On Mechanical Properties And Shrinkage Properties Of Modified Ceramsite Concrete

Ceramsite concrete has been widely used in engineering because of its light weight,strength design,and good heat insulation.However,for ceramsite concrete,compared with ordinary concrete,the low strength and large shrinkage are the great disadvantages of ceramsite concrete,which is also the main reason that ceramsite concrete is not widely used.This article changed the characteristics of ceramsite through various measures such as crushing and drowning,in order to solve the problems of bad grading of ceramic grains and high water absorption rate,thereby increasing the strength of concrete.And then add Cementitious materials such as fly ash and slag powder,in order to study its impact on compressive strength,autogenous shrinkage and drying shrinkage of ceramsite concrete.The research results are as follows:(1)After the crushing of the ceramsite,the particle gradation meets the requirements of continuous gradation,which can significantly improve the compaction and homogeneity of the ceramsite concrete,thereby increasing the compressive strength of the ceramsite concrete,but the increase of open pores of the ceramsite after crushing results in an increase in water absorption.The water absorption of ceramics treated with hydrophobic water is significantly reduced.When the silicone emulsion is used as water repellent,the hydrophobic treatment effect is best.After the water repellent treatment,working performance of the cer amsite concrete mixture becomes better,and its strength is also higher than that of the ceramsite concrete,which is not treated with water repellent.(2)Compared with the reference ceramsite concrete,the early strength of the concrete with fly ash and slag powder is lower,but the later strength is higher,and the late compressive strength of the concrete is higher than that of the base ceramsite concrete.When the proportion of fly ash and slag powder is the same,with the increase of total amount of fly ash and slag powder,the early compressive strength of concrete gradually decreases,and the later compressive strength of concrete increases gradually.When the total amount of fly ash and slag powder is constant,with the increase of the proportion of fly ash and slag powder,that is,the relative increase of fly ash and the relative decrease of slag powder,the compressive strength of ceramsite concrete decreases gradually,but the difference of compressive strength becomes smaller and smaller as the age increases.For ceramsite concrete,the early stage and later stage strength of ceramsite treated by water repellent are much higher than that of dry ceramsite and pre wetting ceramsite.(3)Compared with reference ceramsite concrete,the autogenous shrinkage and drying shrinkage of ceramsite concrete mixed with fly ash and slag powder are lower than those of reference concrete.When the proportion of fly ash and slag powder is the same,the autogenous shrinkage and drying shrinkage of ceramsite concr ete decrease with the increase of total amount of fly ash and slag powder.When the total amount of fly ash and slag powder is constant,with the increase of the ratio of fly ash and slag powder,that is,the relative increase of fly ash and the decrease o f slag powder,the autogenous shrinkage and drying shrinkage of the ceramsite concrete gradually decrease.With the addition of fly ash and mineral powder,the effect of fly ash in reducing autogenous shrinkage is more obvious,the amplitude of increasing dry shrinkage of mineral powder is less than that of decreasing drying shrinkage of fly ash.The autogenous shrinkage and drying shrinkage of ceramsite concrete with water repellent treatment and preweting treatment are much lower than that of dry ceramsite.