## 1 Introduction  
Pervious concrete is a special type of Portland cement concrete composed of rationally graded coarse aggregate and cementitious materials which provide the mixture with an interconnected macro-pore internal structure [1; 2]. Because of the structural characteristics, many benefits can be achieved by using pervious concrete, including quick water drainage, tire-pavement interaction noise abatement and reduction in urban heat island effect [2; 3; 4; 5; 6; 7]. Because of these benefits, pervious concrete is widely used nowadays and it is attracting extensive concerns. In the US, pervious concrete pavements are considered as a structural infiltration best management practice (BMP) [8; 9]. Generally, the porosity of a typical pervious concrete varies in the range of 15-25% [10] and the water permeability coefficient is about 2-6 mm/s [11]. The aggregate gradation for the pervious concrete typically consists of single-sized coarse aggregates. Cemertitious material is used to coat and bond the aggregates together. Right now, there is no standard which gives the optimal cement content in the pervious concrete design. Cement content in literatures varied from 150 [12] to 500 kg/m\({}^{3}\)[13] according to different design purposes. The cementitious material coating thickness has been found to be a very important factor in assessing the structural and hydrological performances of pervious concrete [14; 15]. An increase in the cement content generally increases the paste thickness around the aggregate, which may lead to a higher strength of pervious concrete but will defeat the purpose of using pervious concrete pavements in providing better permeability. It has been reported that 4200 million metric tons of cement was produced worldwide [16] in 2016. The production of cement increases the carbon dioxide emissions, which presents a serious environmental burden. Using alternative materials (fly ash, blast furnace slag, et al.) to partially replace the cement is a sustainable approach to reduce the carbon dioxide emissions and is more environment-friendly. Fly ash (FA) is a by-product of the process of coal burning. The fly ash cannot be directly released into the atmosphere because of the serious air pollution. All around the world, fly ash is generally stored at coal power plants or placed in landfills, which occupies a great quantity of soils and induces soil contamination. Therefore, the comprehensive utilization of fly ash is imperative. Fly ash generally includes substantial amounts of silicon dioxide (SiO\({}_{2}\)), aluminum oxide (Al\({}_{2}\)O\({}_{3}\)), calcium oxide (CaO), etc., which makes it possible to be used in the concrete preparation because these components also extensively exist in cement. Blast furnace slag (BFS) is a by-product of iron and steel-making. The disposal of BFS has become a thorny and expensive process as a result of the increasing strictness of environmental regulations. BFS generally consists primarily of silicates, alumina-silicates, and calcium-alumina-silicates. Nowadays, the utilizations of FA and BFS in the cement concrete industry bring lots of environmental and economic benefits. The use of FA and BFS in ordinary concretes has been confirmed as a sustainable way to provide better or comparable properties of concrete in some aspects. FA and BFS were reported to increase the early-term thermal cracking resistance because of the lower hydration speed in comparison to ordinary Portland cement [17]. On the other hand, the slow hydration speed leads to a slow strength increase, so FA and BFS generally have a negative effect on the short-term strength development, while FA and BFS could both slightly increase the long-term strength [18]. Generally, FA and BFS which are used to partially replace the cement are very fine and show glassy texture. The small size and glassy texture of FA and BFS make it possible to reduce the water consumption to reach the required workability of the fresh concrete [17; 19; 20].