Research On Toughnesses And Their Correlation Of Polypropylene Fiber Reinforced Self-compacting Lightweight Aggregate Concrete

Self-compacting lightweight aggregate concrete has the advantage of ease of construction and light weight, but it has the shortcoming of brittleness and lack of toughness. Mixing polypropylene fibers in the self-compacting lightweight concrete, can be greatly improve its brittle defects,to reach the effect of enhance its toughness. But nowadays, there are few research about the toughness of polypropylene fiber reinforced self-compacting lightweight aggregate concrete,especially there is less research for the shear toughness, greatly limiting its scope of application. In this paper, the following aspects of polypropylene fiber reinforced self compacting lightweight aggregate concrete flexural toughness,shear toughness and toughness correlation were studied.(1)This paper researched the flexural toughness use of the notched beam test method(three-point bending) for flexural toughness of two kinds of mix different content polypropylene fiber reinforced self compacting lightweight aggregate concrete,which include large-diameter polypropylene fiber or small-diameter polypropylene fiber,with the post-crack strengths(PCSm)and the flexural toughness factor(FT) evaluate its flexural toughness, in addition,compared with the results of the test method(four-point bending) for flexural toughness.(2)Adopts the improved two-sided direct shear tests for the shear properties of the polypropylene fiber reinforced self compacting lightweight aggregate concrete, referring to bend toughness evaluation methods, use of shear toughness index(STm)evaluate its shear properties at each deflection under the given deflection.(3)The toughness ratio “k” is defined with the ratio of STm and FT in each deflection, fitting “k” and deflection respectively put to use the linear and polynomial,and deduced the correlation expression, then draw the correlation between the expression of STm and FT.The results showed that the effect of large-diameter polypropylene fiber is obviously better than small-diameter polypropylene fiber; the toughness index of small-diameter polypropylene fiber reinforced self compacting lightweight aggregate concrete is not particularly increasing with the increase of the fiber content, on the contrary, when the fiber content increases to a certain degree, the toughness decreases; in the large-diameter polypropylene fiber content range 0.7% to 1.5%, with the increasing of fiber content,the toughness of self-compacting lightweight aggregate concrete increased significantly; the notched beam method is more suitable for small-diameter small-diameter polypropylene fiber reinforced concrete which has small-diameter for its toughness test study than four-point method; there is a correlation between the flexural toughness and shear toughness of high flowing polypropylene fiber reinforced self compacting lightweight aggregate concrete, the relationship between correlation in conformity with the quadratic polynomial.