Research On Properties Of Reactive Powder Concrete Anti-collision Wall Materials

Reactive powder concrete(RPC)is an ultra-high performance cementitious composite material with low water-cement ratio,elimination of coarse aggregates,incorporation of fibers and a variety of mineral admixtures.It has the advantages of high strength,high toughness and excellent durability,and has been used in bridge structures,high-rise buildings,marine and nuclear power engineering and other fields.While the existing ordinary concrete containment walls have disadvantages such as easy cracking,low strength,brittleness and poor durability performance,based on the advantages of high strength and high durability of RPC,it can be used for the construction of containment walls to replace the traditional ordinary concrete containment walls.However,since RPC is still a new material,its ratio,impact resistance and high temperature resistance need to be optimized in order to meet the requirements of the crash wall,so as to meet the safety and economy of the crash wall structure.Therefore,this paper takes RPC material as the research object,carries out the ratio design,and conducts the research on its impact resistance through the drop hammer impact test.on this basis,the static and dynamic characteristics of RPC material after high temperature are studied systematically,focusing on the analysis of the effect of temperature and fiber doping on the impact resistance of RPC material after high temperature.combined with the current actual construction method,the effect of different maintenance conditions on the The study also explores the effect of different maintenance conditions on the impact resistance of RPC materials.The main research contents are as follows:(1)With steel fiber(SF)admixture,rubber(R)substitution rate and water-cement ratio(w/b)as response factors,the response surface method(RSM)was used to design different matching ratios,and a three-factor,three-level response surface model with compressive strength,number of initial cracking hammer blows,number of breaking hammer blows,flexural initial cracking strength and equivalent bending strength as responses was established to study the relationship between response and variables,establish the relationship equation,carry out multi-objective optimization of the response results to obtain the best proportioning scheme,and conduct experimental verification and water permeability resistance analysis on the best proportioning scheme and multi-objective optimization results given by the response surface.(2)On the basis of water-cement ratio and rubber substitution rate,the damage morphology,mass loss,compressive strength and impact resistance loss after high temperature of RPC with different steel fiber doping are explored,and the calculation model between mechanical property parameters and temperature is established.(3)The effects of two types of curing methods,natural and autoclave,on the compressive strength and impact resistance of RPC are investigated,and the changes in the compressive strength and impact resistance of RPC materials under the two curing regimes before and after high temperature are analyzed,with the aim of improving the mechanical properties of RPC materials at room temperature and high temperature,so as to achieve safe applications in structural engineering.