Experimental Study On Binary Superposition Mix Design Method For Steel Fiber Reinforced Concrete

The Steel fiber reinforced concrete is a new kind of multiply-composite material whichthe steel fibers are distributed in the concrete. The steel fibers can hinder expansion ofmicro-cracks inside the concrete and reduce the emergence and development of themacro-crack. But steel fiber reinforced concrete mix design method does not form aconsensus because of the complex mix design. In this paper, The binary superposition mixdesign method for SFRC is put forward and the feasibility of the mix design is investigated bytesting. The main research works are as follows:1、The steel fiber reinforced concrete mix design binary superposition is proposed Basedon ordinary concrete which maintain the water-cement ratio and sand rate unchanged and thequality of steel fiber considered in the calculation of sand ratio.2、The steel fiber reinforced concrete of CF40、CF50、CF60were configured by Binarysuperposition method. The effects of the water-cement ratio, steel fiber volume fraction andfiber coating thickness on the cube compressive strength, splitting tensile strength, bendingtensile strength of steel fiber reinforced concrete were studied. And regulations and existingfiber concrete structure technical regulations the relevant strength formula conductcomparative analysis. The results show that: The steel fiber reinforced concrete poured bySteel fiber concrete mix design binary superposition had good workability and the basicmechanical properties satisfied the certain request which avoid the adjustment of the waterconsumption and sand rate according to the fiber volume fraction ruling by current rode.3、The150mm×l50mm×550mm beam specimens were poured to test the flexuraltoughness. The results showed that: the change rule of load-deflection curves of SFRC withvariation of strength grade associated with fiber volume fraction. The flexural toughnessindexes of SFRC beams increased to an ideal elastic-plastic material toughness index valuegradually with the increase of the fiber volume ratio and the bending load-deflection curves were more fullness. The first crack strength and ultimate strength of SFRC specimen did notchange significantly with the variation of fiber coating thickness, but the flexural toughnesscurves changed greatly. The expression of bending stress-deflection span ratio was putforward.