Experimental Research On Spalling Strength Of Reactive Powder Concrete

Performances on spall fracture of concrete and steel fiber reinforced concrete are discussed in the dissertation:technique of spall experiment,spall strength of concrete material, mechanism of spall fracture, the influence of compressive damage on spall and characteristic of spall fracture about steel fiber reinforced concrete.When the concrete components are subjected to impact or explosive loading in the applications, compressive waves are generated and then propagate through the concrete components. The compressive waves will be reflected back at the free surface of construction as tensile waves such that the concrete constructions may be fractured by the tensile waves in the form of spalling. Spall fracture is the most common failure for of concrete components subjected to impact or explosive loading. The studies about spalling of concrete material are few, due to the difficulties of experimental techniques, and have the important values in engineering applications and academic research domain.Reactive powder concrete is a new high-performance concrete, and while high-strength fiber is added to the concrete , the dynamic tensile of RPC will be improved significantly .On the basis of considering the influence of waves dispersion to the test ,the study of RPC is carried out using Hopkinson bar.Four kinds of fibers are used to improve mechanics of RPC in the test, namely, steel-cotton fiber, coppered steel fiber, hookish steel fiber and polypropylene Fiber .While the sorts of fiber are changed, volume content of fibers is altered .The volume content of steel-cotton fiber, coppered steel fiber, hookish steel fiber is 1%-5%, and polypropylene fiber is 1%-2%, so there are 18 mix ratios including plain concrete. By comparison in spalling strength, static tensile strength, static compressive strength and failure modes of all mix ratios, the function of different fibers and volume contents in strengthening is expounded, and strengthening mechanism is discussed.The results of the test show four fibers could improve dynamic and static mechanical property of fibers reinforced RPC significally, but the effects are different. Conclusions are drown that the static mechanical property depends on fibers'length , slenderness ratio, volume content and density, and dynamic mechanical property rests with fibers'length, slenderness ratio, volume content ,and fibers'density influences little.