Study On Dynamic Mechanical Properties Of Reactive Powder Concrete Modified By Rubber Powder

Reactive powder concrete is a kind of ultra-high performance concrete which has many advantages,such as good mechanical properties,remarkable volume stability and excellent durability,and it has been widely used in the fields of construction,nuclear engineering and anti-explosion structure.In practical application,Reactive Powder Concrete(RPC)is inevitably subjected to dynamic load such as impact,earthquake and explosion,and concrete shows different mechanical properties at quasi-static loading,which poses higher requirements on the impact resistance of RPC.At present,the researches on RPC concentrate on the preparation technology and quasi-static mechanical properties,however,the studies of dynamic mechanical properties and impact toughness under impact loading are relatively absent.This paper aims to initiate systematic study to on this aspect.In this paper,the impact compression tests of RPC with different rubber powder content(equal volume substitution method,0%,5%,10% and 15%)were carried out under different strain rates using ?38mm SHPB test device,the impact failure morphology and dynamic stress-strain curve of RRPC(RPC modified by rubber powder,RRPC)were obtained,and the effect of strain rate on peak stress and peak strain of RRPC was analyzed.The results showed that RRPC presents obvious strain rate effect that the peak stress increases with the increasing strain rate,and the DIF(Dynamic Improve Factor,DIF)of materials increased with the increase of rubber powder content.The peak strain ascended with the increase of strain rate,as well as adding rubber powder.The specific energy absorption index was introduced to evaluate the impact toughness of materials,and the results showed that the impact toughness of RRPC increased with the increase of both strain rate(the maximum increase is 25.6%)and rubber powder content.The dynamic damage constitutive model was established in the light of the hypothesis of strain equivalence and the damage variable D of material was determined based on the Weibull distribution.The dynamic damage model is well-suited and it can effectively reflect the toughness of the material through the parameter m.And the validity of the model can be proved by the experimental data which are consistent with the calculating model.The finite element model of RRPC under impact loading was established using LS-DYNA finite element analysis software,and parameters of HJC constitutive model were ensured,meanwhile,the laws in the whole loading process of stress and strain variation were obtained.The impact failure shape of the specimen was reproduced,and the numerical simulation results were in good agreement with the test results.The application of RPC in anti-impact and anti-explosion structures is the frontier research of concrete materials.The dynamic mechanical properties of RPC modified by rubber powder have been systematically analyzed,what’s more,the impact resistance and impact toughness of the material are improved.Consequently,RPC is profitable to be applied in the engineering field.