Research On Bond Properties Between Plastics-steel Fiber Reinforced Lightweight Aggregate Concrete And Deformed Bars

As a new green construction material， plastics-steel fiber reinforced lightweightaggregate concrete has many advantages in high rise buildings and long span structures，such as light weight， good seismic performance， good heat preservation and gooddurability． So study on the bond properties between plastics-steel fiber reinforcedlightweight aggregate concrete and deformed bars has important practical significance topromote its application in structural engineering．In this paper，the effect of six factors onthe bond properties were researched by the pullout test，such as amount of fiber，matrixstrength grade，type of lightweight aggregate，bar diameter，bar anchorage length andthickness of concrete cover．The actual distribution and the change rule of the bond stressare researched with the strain gauges stuck in bars．The main conclusions are as follows：The bond properties between bars and matrix of LC40and LC35strength grade canall be improved by plastics-steel fiber with suitable adding amount．The higher matrixstrength and lightweight aggregate strength are，the better bond properties．The bondproperties between bars and matrix of LC40strength grade which prepared with fly ashaggregate Ⅰ are the best when the amount of fiber is4kg/m3．The bond properties influenced obviously by bar diameter，bar anchorage length andthickness of concrete cover．The ultimate bond strength firstly increases and then decreasesbut the ultimate bond slip always decreases with the increase of bar diameter．The longeranchorage length is，the less ultimate bond strength and slip are．The ultimate bondstrength firstly increases and then be stable but the ultimate bond slip continues to increasewith the increase of relative thickness of concrete cover．The distribution of bond stress in anchorage length shows that the plastics-steel fiberand high strength lightweight aggregate can make the stress distribute uniformly andtransfer better．The larger the diameter is，the smaller the bond stress is．And the bondstress distributes equally and transfers quickly in the bar of short anchorage length．The fitting formula of ultimate bond strength between plastics-steel fiber reinforcedlightweight aggregate concrete and bars is obtained．The calculations of anchorage length show that plastics-steel fiber can shorten it obviously．The anchorage length of bar inplastics-steel fiber reinforced lightweight aggregate concrete is suggested to be calculatedaccording to the code for design of concrete structures (GB50010-2010) which has largeenough safety margin．And this suggestion can provide a reference for the application ofpractical engineering．...