Influence Of Fiber On Workability And Mechanical Properties Of Self-compacting Concrete

As a kind of high flow concrete,self-compacting concrete(SCC)has many specific advantages,such as ensuring the good compactness of concrete,improving production efficiency,improving working environment and safety,avoiding the abrasion of formwork caused by vibration,etc.In addition,due to the need to add mineral admixtures in the production process of SCC,it can not only reduce the amount of cement,reduce the overall cost of the project,but also make full use of industrial waste,which is conducive to environmental protection.However,the durability of SCC after hardening is poor.Adding fibre into SCC can improve its durability.Therefore,in order to improve the workability and mechanical properties of SCC,the research on the content of steel fibre(SF),polypropylene fibre(PPF)and hybrid fibre(HF)was carried out.The main research contents and achievements are as follows:Firstly,the mix proportion of SCC was studied.The mix proportion of SCC with strength of C60 was designed by absolute volume method.By testing its workability,the mix proportion of the primary design was adjusted,and the W/B of SCC in this paper was finally determined to be 0.25,and the replacement rate of fly ash was 30%.Secondly,through slump flow test,T500 test,J-ring test,L-box test and GTM test,the influence of SF,PPF and HF content on SCC performance was studied.The results show that both SF and PPF can reduce the filling capacity and gap permeability of SCC,and improve the segregation resistance.When the volume content of PPF is 0.1%,the volume content of SF is 0.3%,the workability of SCC is the best.Finally,the effects of SF,PPF and HF content on the mechanical properties of SCC were studied by compressive strength test,splitting tensile strength test and flexural strength test.The results show that SF can significantly improve the splitting tensile strength and flexural strength of SCC.PPF can also improve the splitting tensile strength and flexural strength of SCC,but the effect is not as significant as SF.The mechanical properties of hybrid-fibre reinforced self-compacting concrete(HFRSCC)are better than those of fibre-reinforced self-compacting concrete(FRSCC).When the volume content of PPF is 0.1% and the volume content of SF is 1.2%,the compressive strength is the highest;when the volume content of PPF is 0.2% and the volume content of SF is 0.5%,the splitting tensile strength and flexural strength are the highest.