Mix Proportion And Volume Stability Of Special Concrete For Prefabricated Vertical Joint

The joint concrete pouring of precast concrete members is the key construction link related to the overall performance and engineering quality of prefabricated concrete structure.In this paper,the effects of water binder ratio,the amount of expansion agent and the type of mineral admixture on the basic mechanical properties and volume stability of self compacting concrete are studied :(1)According to the SCC test specifications,the performance tests are carried out,and the results show that the performance of each group of tests meet the requirements of self compacting.(2)The effects of different water binder ratios(0.25,0.31,0.40 SCC and 0.31,0.37,0.46 control of the same strength of ordinary concrete),the amount of expansion agent(0%,8%,10%,12%),the type of mineral admixture(fly ash: slag powder: limestone powder = 1:0:2,1:2:0,1:1:1),curing conditions(unconstrained,with mold curing for 7d)on the mechanical properties of concrete were studied.The results show that the higher the water binder ratio is,the lower the strength is.The increase of expansion agent makes the compressive strength and splitting tensile strength of cube and axis decrease,but the elastic modulus has no obvious change trend.Slag powder can improve the strength of SCC.Limit curing to reduce the negative effect of expansive agent on strength reduction.(3)The influence of SCC with different expansion agent(0%,8%,10%,12%)and a group of ordinary concrete with the same strength on the early age non-contact self shrinkage was studied.The results show that the expansion agent can inhibit the early self shrinkage of SCC.(4)The effects of different water binder ratios(0.25,0.31,0.40 SCC and 0.31,0.37,0.46 control of the same strength ordinary concrete),the amount of expansion agent(0%,8%,10%,12%),the type of mineral admixture(fly ash: slag powder: limestone powder = 1:0:2,1:2:0,1:1:1)on the self shrinkage of concrete were studied.The results show that the larger the water binder ratio is,the smaller the self shrinkage of concrete is.The addition of expansion agent can effectively compensate the self shrinkage of concrete.It is beneficial to control SCC self shrinkage by selecting the appropriate mineral admixture.(5)The effects of different water binder ratios(0.25,0.31,0.40 SCC and 0.31,0.37,0.46 control of the same strength ordinary concrete),the amount of expansion agent(0%,8%,10%,12%),the type of mineral admixture(fly ash: slag powder: limestone powder = 1:0:2,1:2:0,1:1:1)on the dry shrinkage of concrete were studied.The results show that under the dry condition,each group of concrete presents shrinkage deformation.With the increase of water binder ratio,the drying shrinkage of concrete decreases gradually.The expansion agent can also effectively control the drying shrinkage of SCC.Selecting the appropriate mineral admixture can reduce the drying shrinkage of concrete.