Experimental Study On Early Strong Micro Expansion Self-compacting Concrete

Self-compacting concrete has good fluidity,filling and clearance.In the process of flowing and pouring,no segregation and bleeding phenomenon and no vibration measures,only depend on its weight to achieve self-compacting effect.It can solves the problem of pouring steel,steel-intensive,complex structure and other parts of the concrete.Self compacting concrete can be used to simplify the construction process,so as to improve the construction efficiency,shorten the construction period and save the construction costs.Therefore,self compacting concrete has been widely used at home and abroad.However,self-compacting concrete due to the excessive usage of the unit volume of gelled material,makes the volume stability of concrete is insufficient.In this paper,adopts the local raw materials of Liaoning and with the orthogonal experiment method,successfully developed high early strength and micro expansion volume of self-compacting concrete after hardening.It will be developed C80,C60 and C40 early strength micro expansion self-compacting concrete used in the steel tube to verify the expansion property of the early strength micro expansion self compacting concrete.The following results are obtained:(1)C80,C60 and C40 early strength micro expansion self-compacting concrete water reducing agent dosage of 1%,0.7%and 0.5%respectively;The best water binder ratio was 0.24,0.29 and 0.34 respectively.The best total amount of gelled materials was 600kg/m3,540kg/m3and 440kg/m3;The best sand rate was 0.46,0.47 and 0.49 respectively.(2)When superfine fly ash and slag instead of 30%of the total cement and superfine fly ash and slag content ratio of 2:1,the concrete work ability and mechanical properties of the optimal mixture.(3)With the increasing content of silica fume,mix concrete working performance becomes better then worse and the compressive strength of each age gradually increased.When silicon ash content was 8%,has a better working performance and mechanical performance.(4)With the increasing of the dosage of modified expansive agent,the working performance of concrete gradually becomes poor,early compressive strength increased significantly,restricted expansion rate increased gradually.Under the premise that satisfy the working properties,mechanical properties and expansive performance at the same time,the modified expansive agent content of 5%is reasonable.In the modified expansive agent content is 5%,the 1d concrete strength increased by 70.1%,the 3d strength increased by 27.8%;C80,C60 and C40 concrete 14d restricted expansion rate were 2.29×10-4,2.37×10-4 and 2.45x 10-4,28d restricted expansion rate were0.24×10-4?0.35×10-4 and 0.29×10-4,concrete were micro expansion.(5)In axial compression test,the elastic stage of the early strength micro expansion of self-compacting concrete filled steel tubular short column is longer than that of the normal self-compacting concrete filled steel tubular short column.The elastic stage of early strength micro expansion of self-compacting concrete filled steel tubular short column is finished by the 80%?85%of the ultimate load.The elastic stage of normal self-compacting concrete filled steel tubular short column is finished by the 60%-70%of the ultimate load.(6)In the elastic stage,the hoop strain of early strength micro expansion of self-compacting concrete filled steel tubular short column is greater than the normal self-compacting concrete filled steel tubular short column.(7)In the elastic stage,the longitudinal strain of early strength micro expansion of self-compacting concrete filled steel tubular short column is less than the normal self-compacting concrete filled steel tubular short column.(8)Different strength of self-compacting concrete filled steel tubular short column axial compression,with the improvement of concrete strength,ultimate load of self-compacting concrete filled steel tubular short column corresponding to the vertical deformation in decrease.(9)In axial compression test,confining effects of early strength micro expansion of self-compacting concrete filled steel tubular short column is earlier than normal self-compacting concrete filled steel tubular short column.