Influence of matrix material on performance of ECC with aeolian sand along railway
In order to solve the problems of scarce river sand and high transportation costs in the Gobi desert region,and to mitigate desert railway wind-sand disasters,the experimental study on the preparation of regional engineered cementitious composites(ECC)along the desert railway was carried out.The effects of different aeolian sand content(S/C),fly ash content(FA/C),and water-binder ratio on the performance of ECC were measured by orthogonal tests.A reasonable mix design was determined initially based on the cracking form and load-deflection curves of three-point bending tests,the fluidity,apparent density,mechanical properties,and toughness of the range analysis,and microscopic analysis.On the basis,the effects of different fly ash content on the compressive properties,bending properties,tensile properties,and deformation capacity of ECC were further explored.Fluidity and bending properties were affected most by the aeolian sand,and the fly ash had the most significant effect on the apparent density and compressive properties.The overall properties of the material were best when the content of aeolian sand was 0.75,fly ash was 1.50,and the water-binder ratio was 0.34.With those values the fluidity,compressive strength,and flexural strength were 151 mm,50.1 MPa,and 17.3 MPa,respectively.The ultimate tensile strain of the material fluctuated between 2%and 3.5%when the fly ash content was increased from 1.50 to 3.50,and the maximum value of 3.5%appeared when the fly ash content was 2.50.The minimum crack width of axial tensile specimen was 100 µm when the fly ash content was 3.0 and the number of cracks was the largest and the spacing was the smallest.The fiber surface had obvious scratches and attached hydration products when the aeolian sand content was 0.75 and fly ash content was 1.5,the fiber could better exert a bridging effect in the matrix.The matrix density was lower when the water-binder ratio was 0.36,and the anchoring effect of the matrix on the fibers was weakened.The research results can provide a theoretical basis for the preparation of high ductility concrete in railway engineering in desert areas.
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维普
