Study On Preparation And Basic Mechanical Rties Of Fiber Reinforced Self-compacting Lightweight Aggregate Concrete

At present,urban buildings are developing in the direction of towering,large span,high reinforcement ratio and high ductility.New concrete with light weight,high strength,self-leveling and high toughness is the future development direction and trend.Fiber reinforced self-compacting lightweight aggregate concrete(FSLC)has the high fluidity of self-compacting concrete(SCC)and the light weight and high strength of lightweight aggregate concrete(LWAC),as well as the crack resistance,toughness and impermeability of fiber,Has great development potential and research value.This paper carries out the research on the mix design,working performance,basic mechanical properties and FSLC fracture performance of self-compacting lightweight aggregate concrete(SCLC)and FSLC.The main research contents are as follows:Using the theory of close packing of aggregates and the method of minimum water requirement of powder materials,determine the optimal volume ratio of different grades of coarse aggregate(5～10mm,10～15mm)and fine aggregate,as well as the best quality among different powder materials ratio.Change the water-binder ratio(0.2,0.25,0.3,0.35,0.4)and mortar film thickness(1.5mm,1.7mm,1.9mm,2.1mm,2.3mm)to prepare SCLC with different strength levels and self-compacting properties.Adjust the volume content of steel fiber(0.25%,0.5%,0.75%,1%)and SCLC strength(LC40,LC50,LC60)to explore the effect of steel fiber on the self-compaction,basic mechanical properties and fracture properties of SCLC with different strength levels.The law of influence.Research results:Through the quantitative calculation of the mix ratio,SCLC with different strength grades and self-compacting properties were successfully prepared,and the 28-day strength reached 76.3MPa.The increase in water-binder ratio and mortar film thickness can improve the fluidity and gap passing capacity of SCLC,but it is also easy to cause segregation and bleeding of SCLC.The addition of steel fiber has an adverse effect on the fluidity and gap passing capacity of SCLC,but it can enhance the anti-segregation ability.When the volume of steel fiber is increased from 0.25%to 1%,the split tensile strength of LC40 increases from 11%to 25%;LC50 increases from 4%to 20%;LC60 increases from 3%to 19%,and the resistance of LC40 increases The increase in rupture strength increased from 9%to 26%;LC50 increased from 5%to21%;LC60 increased from 3%to 20%,but the compressive strength and elastic modulus increased little.The minimum dry apparent density of SCLC and FSLC prepared in this paper are 1731kg/m~3and 1769kg/m~3,respectively.The dry apparent density decreases with the increase of water-binder ratio and mortar film thickness,and increases with the increase of the volume of steel fiber..Steel fiber provides three different resistances,such as"prestressed concrete bridge",bonding friction,and resistance to deformation,in the destruction process of SCLC,which makes SCLC change from brittle failure to ductile failure.The increase in the strength of FSLC has no significant effect on the fracture energy,but it can significantly increase the fracture peak of SCLC.Steel fiber can greatly increase the fracture energy of SCLC and enhance its toughness.The volumetric content of steel fiber increased from 0%to 1%,and the increase in fracture energy of LC40 increased from 422%to 969%;LC50 increased from 342%to 898%;LC60 increased from 481%to 994%.