【摘要】 为了研究水胶比（W/B）对UHPC力学性能及微观发展规律的影响，测试了不同W/B(0.16、0.17、0.18、0.19、0.20)对7、28 d时UHPC的力学性能的影响，采用吸水率和SEM观察UHPC水化产物和孔结构的变化，采用TG和XRD表征UHPC水化产物的变化规律。研究发现：保持流动度不变（230±10）mm，随W/B的增大，UHPC在7、28 d时的力学强度均呈现先上升后下降的趋势，UHPC的W/B为0.18时出现力学性能最优值，对应7 d时的抗压强度和抗折强度分别为149.0、39.3 MPa;28 d时的抗压强度和抗折强度分别为169.2、44.4 MPa。微观分析表明，UHPC水化产物的量与水胶比呈现“正相关”关系。而强度下降的原因是由于W/B较低时，为保证工作性，增加了高效减水剂剂量，造成黏度增大，成型时内部空气无法排除，造成强度下降；W/B较高时，内部孔隙率增加，从而降低UHPC的力学性能。更多还原

【Abstract】 To illustrate the effect of the water-binder ratio(W/B)on UHPC strength development and microstructure evolution,this work tested the impact of different water-binder ratios(0.16,0.17,0.18,0.19,0.20)on the mechanical properties of UHPC at 7 d and 28 d.Water absorption and SEM were used to observe the development of UHPC hydration products and pore structure,TG and XRD were used to characterize the changes of UHPC hydration products.Therein,keeping the flowability constant(230±10)mm,with the increase of W/B,the mechanical strength of UHPC at 7 d and 28 d demonstrates a pattern of initially rising and later decreasing.It appears when the W/B of UHPC is 0.18 optimal value of mechanical properties.The compressive strength and flexural strength at 7 d were 149.0 MPa and 39.3 MPa,the compressive strength and flexural strength at 28 d were 169.2 MPa and 44.4 MPa.Microstructure illustrates that the amount of UHPC hydration products and the W/B show a“positive correlation”relationship.The reason for the decrease in strength is that when the W/B is relatively low,to increase the workability,the dosage of water reducer was improved,which causes the viscosity to increase,and the internal air cannot be removed during molding,resulting in a decrease in mechanical strength.When the W/B is relatively high,internal pores rate increases,therefore reducing the mechanical properties of UHPC.更多还原