Experimental Study On Basic Mechanical Properties Of Steel Fiber Reinforced Lightweight Fly-ash Concrete

Reducing the self-weight of the structure is one of the effective ways to achieve the ultra-modem architectural structure design and construction of super-tall and large span, while using lightweight aggregate concrete can significantly reduce the weight of structure. But tendency of aggregate rising during the mixing process leads to the poor uniformity of lightweight aggregate concrete after pouring molding, what limits its engineering applications.Paper aiming at the problems of lightweight aggregate concrete, combining with the development of new technology of steel fiber and fly-ash concrete, to develop the modern high-performance steel fiber reinforced lightweight fly-ash concrete with green characteristics, the experimental study was carried out to research the basic mechanical performance of the concrete.Specific studies are as follows:(1)The absolute volume method for mix proportion design is adopted in the test by replacing cement with fly-ash equally and putting volume fraction of steel fiber into the calculating formula of sand ratio.(2)Through the study of the multiphase composite material to analysis the influence of water-to-cement ratio, volume fraction of steel fiber, ratio of fly-ash replacing cement and other factors on the workability, apparent density, the compressive strength, tensile strength and elasticity modulus.Through the test we can have the following conclusions:(1)The fresh concrete belong to upper flow regime with good cohesiveness and water-retaining property, the dry apparent density meet the requirements of lightweight aggregate concrete class 1700~1800; the water-to-cement ratio has a great influence on the workability; workability of the mixture concrete declines with the increasing of fraction of steel fiber by volume; fly-ash replacing cement can improve the workability of the mixture concrete.(2)With the increasing of fraction of steel fiber by volume, the failure state tends to plasticity, the cubic compressive strength and axial compressive strength as well as elastic modulus are all increased in certain extent; the ratio of fly-ash replacing cement has a little influence on the compressive properties of concrete; the values of axial compressive strength and elastic modulus of steel fiber reinforced lightweight-aggregate fly-ash concrete meet the Technical Specification for Lightweight Aggregate Concrete.(3) With the increasing of fraction of steel fiber by volume, the axial tensile strength and splitting strength are all increased remarkably; the ratio of fly-ash replacing cement has a little influence on the axial tensile strength and splitting strength; the values of axial tensile strength and splitting tensile strength of steel fiber reinforced lightweight-aggregate fly-ash concrete are superior to the Technical Specification for Lightweight Aggregate Concrete.