制备工艺对纳米纤维素改性透水混凝土性能影响

Influence of the preparation technology on cellulose nanocrystal modified permeable concrete

通过对比4种工艺制备的纳米纤维素改性透水混凝土透水性能和力学性能,确定出合适的制备工艺和纳米纤维素掺量。结果表明:采用二次裹浆工艺,CNFs掺量为0.018%制备的透水混凝土结果最优,抗压强度为26.79 MPa、抗折强度为3.18 MPa,透水系数为7.33 mm/s、孔隙率为15.95%;0.018%掺量CNFs能够改善透水混凝土内部孔隙结构,不过度降低透水系数和孔隙率,提高抗压强度和抗折强度,但掺量过多时,浆体流动性变差、密实度降低、力学性能变差;透水混凝土微观结构表明,0.018%掺量的CNFs能够改善界面过渡区,减少界面孔隙和裂缝,但过多的CNFs掺量导致水化产物密实度降低,界面过度区连接变差,导致力学性能下降。

The four different mixing processes have been ranked in order to determine the effect of processes on the basic properties of pervious concrete modified by nanofibrllated cellulose(CNF),.The experimental results indicate that in second-cement-wrapped stone-feeding method,0.018%of CNFs achieve the best pervious concrete effect with compressive strength of 26.79 MPa,the flexural strength of 3.18 MPa,water permeability of 7.33 mm/s,and porosity of 15.95%.0.018%admixture of CNFs can improve the internal pore structure of pervious concrete,without unduly decreasing the permeability coefficient and porosity,and improving the strength of pervious concrete,but when the amount of CNFs exceeds,just the opposite result.The microstructure of pervious concrete shows that CNFs content of 0.018%can improve the connection of interface transition zone and reduce interface pores and cracks,but too much CNFs content leads to the decrease of hydration product compactness,the deterioration of the connection of the interface excess zone,and the deterioration of mechanical properties.