浆体流变特性对透水混凝土性能的影响

Effect of the Cement Paste Rheological Characteristics on the Properties of Pervious Concrete

为研究浆体流变特性对透水混凝土力学与透水性能的影响规律,通过减水剂与增黏剂掺量的变化调配出5种不同流动度及6种不同塑性黏度的水泥浆体,并固定浆集比配置出对应的透水混凝土。采用光学显微镜图像分析透水混凝土中骨料颗粒表面浆体裹附层厚度,以水泥浆体的拉拔黏结强度表征浆体与骨料的黏结强度,在研究浆体流动度及塑性黏度对浆体拉拔黏结强度、骨料颗粒表面浆体包裹层厚度影响的基础上,进一步探讨了浆体流变特性对透水混凝土抗压、抗折强度、空隙率以及透水系数的影响规律,揭示出浆体流动度与塑性黏度对透水混凝土力学与透水性能的作用原理。研究结果表明:随着浆体流动度及塑性黏度的增加,透水混凝土力学性能呈现先提高后降低的趋势,而透水混凝土的透水系数则随着浆体流动度的增加逐渐降低,随着浆体塑性黏度的增加逐渐增加;结合浆体流变性能对浆体自身拉拔黏结强度及骨料颗粒表面浆体包裹层厚度的影响发现,浆体流变特性主要通过影响浆体自身黏结特性而作用于透水混凝土力学性能,通过影响骨料颗粒表面浆体包裹层厚度及其分布状态而作用于透水混凝土的透水性能;在进行透水混凝土配合比设计时,可以通过调控浆体的流变特性,达到兼顾透水混凝土力学性能与透水性能的目的。

Herein,a study on the effect of rheological characteristics of the cement paste on the mechanical properties and permeability of the pervious concrete is presented.Five kinds of fluidity and six kinds of plastic viscosity of cement pastes were prepared by adjusting the content of the water-reducing agent and tackifier.The corresponding pervious concrete with a fixed ratio of cement and aggregate were also prepared.An optical microscope was used to observe the thickness of the paste coating on the surface of the aggregate particles in the pervious concrete,and the pull-off bond strength of the paste was used to characterize the bond strength between the paste and the aggregate.Based on the study of the effects of the paste fluidity and plastic viscosity on the bond strength of the paste and the paste thickness on the surface of aggregate particles,the effects of paste rheological characteristics on the compressive strength,flexural strength,porosity,and permeability coefficient of pervious concrete were tested.The working principle of the fluidity and plastic viscosity of the paste on the mechanical properties and permeability of the pervious concrete were revealed.The results show that the mechanical properties of the pervious concrete first increase and then decrease with the increase in paste fluidity and plastic viscosity.As the fluidity of the paste increases,the permeability of the pervious concrete decreases gradually.Moreover,as the plastic viscosity of the paste increases,the permeability of the pervious concrete increases gradually.Combining the influences of the rheological characteristics of the cement paste on the bond strength and the paste thickness on the surface of aggregate particles,it is found that the rheological characteristics of the cement paste mainly act on the mechanical properties of the pervious concrete by affecting the bond strength of the paste and on its permeability by affecting the paste thickness and distribution on the surface of aggregate particles.The rheological characteristics of the cement paste can be adjusted to balance the mechanical properties and permeability of the pervious concrete in the previous concrete mix proportion design.