Study On Material's Fracture Mechanical Properties Based On Reactive Powder Concrete

RPC is a new developed construction material with the development of material application(such as Silica Fume ,water reducer and etc.) and the development of preparation techniques and the need of engineering construction.With its high performance (high strengh,high durability and high impermeability),it has a potential application future.It's developed for less than ten years,many scholars focus on it and have some experimental researches on its elemental mechanical properties,but its fracture property is initially studied.Few articles give a quantitative or quality analysis about its fracture mechanical property.Through three-point bending tests ,this article makes an elemental study on the mechanical properties and fracture-resisted property of RPC applying Fictitious Crack Model (FCM) conbining with linear elastic fracture mechanics.Sizes of specimens are 300*60*40mm3,whose initial notch-to-depth ratios are 0.25.The different influencing regular of fly-ash fraction,cure conditions,type of fibre (steel fibre and polypropylene fibre) and fibre fraction on the mechanical property and fracture behavior of PRC are studied.The results showed that the peaking load decreases , the brittleness increased but its workability is better with fly ash replacing quartz powder .With hot water curing condition,its ultimate load increases,but its brittleness increases. The results show that polypropylene fraction hardly contribute to the strength of RPC.but it can develop its ductility and conlude that 0.15% is an optional proportion. Steel fibre or hybrid fibre has a remarkable effect on RPC mechanical properties,especially on ductility.The flexural strength and fracture energy is stable with the increase of the volume content of steel or hybrid fibre,but the fracture toughness,pre-critical length of crack,characteristic length and ect show different changing trends with fibre fraction.The article gives the optional fraction of steel and hybrid fibre and gives the relationship between mechanical indexes of RPC.Basing on the datas ,we probe into the fracture process,fracture mechanics and fibre strengthening mechanics of RPC. From the results of the study, we can see that the fracture toughness,fracture energy of RPC is apparently bigger than Normal Concrete,it has a wide application future.