基于正交试验的透水再生混凝土性能优化试验研究

透水混凝土在缓解城市内涝、噪音效应和热岛效应等方面具有广泛的应用前景,但多孔导致的强度偏低限制了其进一步推广应用。本文采用再生粗骨料和聚丙烯纤维配制高性能透水再生混凝土,设计五因素四水平正交试验,采用极差法分析水胶比、目标孔隙率、再生粗骨料取代率、粉煤灰掺量和聚丙烯纤维掺量对透水再生混凝土抗压强度、有效孔隙率、透水系数的影响规律。结果表明:透水再生混凝土抗压强度影响因素的主次顺序为目标孔隙率>再生粗骨料取代率>水胶比>聚丙烯纤维掺量>粉煤灰掺量;透水再生混凝土抗压强度最大为48.26 MPa,此时透水系数为1.96 mm/s;随着目标孔隙率的提高抗压强度呈线性下降的趋势;40%再生粗骨料等质量取代天然粗骨料后,透水再生混凝土的抗压强度达到28.7 MPa,提高119.08%,透水系数增加9.44%;掺入0.11%体积掺量的聚丙烯纤维后透水再生混凝土的抗压强度达到27.4 MPa,提高幅度为10.48%,而且透水性能不会降低。研究结果可以为高性能透水再生混凝土的制备提供依据。

Experimental Study on Performance Optimization of Pervious Recycled Concrete Based on Orthogonal Test

Pervious concrete has wide application prospects in alleviating urban waterlogging, noise effect and heat island effect, but its low strength due to porosity limits its further application. The recycled coarse aggregate and polypropylene fiber were used to formulate high performance pervious concrete. A five-factor, four-level orthogonal test was designed to analyse the effects of water-binder ratio, target porosity, recycled coarse aggregate replacement rate, fly ash content and polypropylene fiber content on the performances of pervious recycled concrete in terms of compressive strength, effective porosity and permeability coefficient using the extreme difference method. The results show that the main factors affecting the compressive strength of pervious recycled concrete are: target porosity>recycled coarse aggregate replacement rate>water-binder ratio>polypropylene fiber content>fly ash content. The maximum compressive strength of pervious recycled concrete is 48.26 MPa and the permeability coefficient is 1.96 mm/s. The compressive strength decreases linearly with the increase of target porosity. The compressive strength of pervious recycled concrete increases by 119.08% to 28.7 MPa and the permeability coefficient increases by 9.44% when 40% of recycled coarse aggregate replaces the natural coarse aggregate by the same amount. The addition of 0.11% by volume of polypropylene fiber increases the compressive strength of pervious recycled concrete by 10.48% to 27.4 MPa, and does not reduce the permeability performance. The results of this study can provide a basis for the preparation of high performance pervious recycled concrete.