Strength, Permeability, and Freeze-Thaw Durability of Pervious Concrete with Different Aggregate Sizes, Porosities, and Water-Binder Ratios

Abstract

Pervious concrete (PC), as an environmental friendly material, can be very important in solving urban problems and mitigating the impact of climate change; i.e., flooding, urban heat island phenomena, and groundwater decline. The objective of this research is to evaluate the strength, permeability, and freeze-thaw durability of PC with different aggregate sizes, porosities, and water-binder ratios. The orthogonal experiment method is employed in the study and nine experiments are conducted. The compressive strength, flexural strength, permeability coefficient, porosity, density, and freeze-thaw durability of PC mixtures are tested. Range analysis and variance analysis are carried out to analyze the collected data and estimate the influence of aggregate size, porosity, and water-binder ratio on PC properties. The results indicate that porosity is the most important factor determining the properties of PC. High porosity results in better permeability, but negatively affects the mechanical strength and freeze-thaw durability. PC of 15% porosity can obtain high compressive strength in excess of 20 MPa and favorable freeze-thaw durability of 80 cycles without sacrificing excessive permeability. Aggregate size also has a significant effect on freeze-thaw durability and mechanical strength. Small aggregate size is advantageous for PC properties. PC with 4.75-9.5 mm coarse aggregate presents excellent freeze-thaw durability. The influence of the water-binder ratio on PC properties is not as significant as that of aggregate size and porosity. An optimal mix ratio is required to trade-off between permeability, mechanical strength, and freeze-thaw durability.functionally and environmentally friendly material [9]. It allows rainwater to permeate into the ground and replenish groundwater, which effectively alleviates the rapid decline of groundwater. In addition, PC pavement can solve other urban environmental problems [10][11][12]. With the development of Chinese sponge city construction, PC will be widely applied in road structure [13]. Therefore, PC is of great significance for mitigating climate change, solving urban problems, and promoting the development of human society [14][15][16].The main properties of PC are strength, permeability, and durability. A porous structure is the key feature of PC, and porosity is the most important factor influencing mechanical strength, permeability, and durability. In general, the porosity of PC mixtures is 15-30% and the corresponding permeability coefficient lies in the range of 1-15 mm/s [17,18]. Higher porosity produces higher permeability, but is disadvantageous to mechanical strength and durability. Due to the absence of fine aggregate and the existence of high porosity, the strength of PC is lower than that of traditional impervious concrete. The compressive strength of PC is 5-30 MPa and tensile strength is 1. 20]. In addition, the freeze-thaw durability of PC is a very important property, especially for PC used in seasonally frozen regions. However, the freeze-thaw durability ...

Laboratory Evaluation of Eco-Friendly Pervious Concrete Pavement Material Containing Silica Fume

“…The permeability coefficients of all groups were about 3.8 mm/s when the porosities of all mixtures were about 15%, which meets the standard requirement of 0.5 mm/s for pervious concrete in the Chinese national standard [34]. Just as the report in the literature [32], the porosity is the most important and direct factor that determines the permeability coefficient of pervious concrete. In terms of mono-sized pervious concrete, when the porosity does not change, the permeability will not change.…”

“…Compared to the non-destructive testing method, in this paper, the compressive strength after freeze-thaw cycles was measured and the compressive strength loss was chosen as the evaluation index for freeze-thaw resistance. The detailed explanation for choosing compressive strength loss can be found elsewhere [32]. The compressive strength after freeze-thaw cycles was characterized by the average strength of three specimens.…”

“…The replacement levels were 3%, 6%, 9%, and 12%, respectively. Based on previous research conducted by our group [32], the aggregate size, designed porosity, and water to binder ratios were chosen as 4.75-9.5 mm, 15%, and 0.30, respectively. In order to improve workability of pervious concrete, superplasticizer was used and the dosage was 0.8% of the cementitious material mass.…”

“…Meanwhile, the permeability coefficients of all mixtures were predicted with the equation between effective porosity and permeability given by Reference [32], and the predicted permeability coefficients are also shown in Figure 8. The data shows that the measured and…”

“…Therefore, it is necessary to carry out research to investigate the mechanical properties and durability of silica fume-modified pervious concrete. Based on previous research conducted by our group [32,33], in order to evaluate the improvement of silica fumes on pervious concrete, silica fume-modified pervious concrete was prepared with equivalent volume method, the porosity, permeability, strength, and freeze-thaw durability of silica fume-modified pervious concrete with different silica fume incorporation levels were studied. Due to the porous structure of pervious concrete, strength loss was adopted to assess the freeze-thaw resistance for pervious concrete.…”