Performance And Mechanism Research On Multi-scale Fiber Reinforced Cement-based Composite

The structural level and the destruction processes of cementitious composites all show more significant multi-scale feature,for this feature,a kind of multi-scale fiber reinforced cement-based composites(MSFRCC)was designed by using polypropylene macro-fiber(PPCF)which has large size and low elasticity modulus and basalt fiber(BF)which has small size and high elasticity modulus,hope to resist cracking in the corresponding level and corresponding stage,and then improve the performance of cementitious composites overall.The basic mechanical properties of MSFRCC were studied firstly,analysing the effect of PPCF or BF on the flexural strength,the compressive strength and the tensile strength of MSFRCC with considering the enhancement coefficient and the hybrid coefficient,and then determine the reasonable mixing content of the fiber.After determining the mixing amount of the fiber,the effect of a fiber or hybrid fibers on the bending toughness,the impact toughness,the frost resistance performance and the salt-frost resistance performance of MSFRCC were researched,evaluating the performance according to the test results and a nalysing the mechanism of the fibers.The research results show that,when PPCF was added alone,with the improvement of fiber content,the peak load,the initial crack deflection and the flexural toughness index of mortar were all increased first and then reduced,the impact toughness index showed an increasing trend,the frost resistance performance showed a decreasing trend,the salt-frost resistance performance was increased first and then lower,When the PPCF content was 0.50%,the peak load and the initial crack deflection of the mortar were the best,and the salt-frost resistance performance was the best.When PPCF and BF were mixed,the fixed PPCF content was 0.50%,and with the improvement of BF content,the peak load,the initial crack number showe d an increasing trend,the initial crack deflection,the flexural toughness index and the ductility index of MSFRCC were all increased first and then reduced,the frost resistance performance and the salt-frost resistance performance was lower,When the BF content was 0.10%,the initial crack deflection,the flexural toughness index and the ductility index were the largest.When PPCF and BF were mixed,the fixed BF content was 0.10%,and with the improvement of PPCF content,the peak load of MSFRCC showed a decreasing trend,the flexural toughness index showed an increasing trend,the frost resistance performance showed a decreasing trend,the salt-frost resistance performance was increased first and then lower,When the PPCF content was 0.50%,the ductility index were the largest,the frost resistance performance was the best.When PPCF and BF were mixed,the fixed PPCF content was 0.50% and the fixed BF content was 0.10%,with the improvement of the length to diameter ratio of BF,the peak load,the initial crack deflection,the flexural toughness index and the ductility index of MSFRCC were all increased first and then decreased,the frost resistance performance was increased first and then lower,the salt-frost resistance performance showed an increasing trend,When the length to diameter ratio of the PPCF was 923,the peak load,the initial crack deflection,the flexural toughness index and the ductility index of MSFRCC were the largest,the frost resistance performance was the best.Evaluating the performance of MSFRCC synthetically,the best hybrid scheme is: the content of the PPCF is 0.50%,the content of the BF is 0.10%,and the length to diameter ratio of BF is 923.