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.

Due to the negative effects that derive from large impervious surfaces in urban areas, pervious concrete has been developed, and has become an environmentally friendly pavement material. As a porous and permeable material, pervious concrete presents an overwhelming advantage in solving urban problems, such as flooding, groundwater decline, urban heat island phenomena, etc. Waste crumb rubber has been verified as a feasible modifier for pavement material. The objective of this paper is to explore the effects of rubber particle size and incorporation level on the permeability, mechanical properties, and freeze–thaw resistance of pervious concrete. Two kinds of rubbers (fine and coarse) with four incorporation levels (2%, 4%, 6%, and 8%) are used in the experiment. Permeability, compressive strength, flexural strength, flexural strain, and freeze–thaw resistance are tested. The results indicate that the addition of rubber slightly decreases strength and permeability, but significantly enhances ductility and freeze-thaw resistance. Fine crumb rubber with a suitable incorporation level could remarkably improve the ductility and freeze–thaw resistance of pervious concrete without sacrificing excessively strength and permeability.

To dispose of the large amount of OSA (oil shale ash) and FA (fly ash) in Northeast China, a novel subgrade material obtained by modifying SC (silty clay) with OSA and FA was produced. First, the effect of F-T (freeze-thaw) cycles and stress states on the resilient modulus of unmodified SC and the modified SC were investigated. Second, the damage ratio was introduced to describe the relationship of resilient modulus versus F-T cycles. Third, the effect of F-T cycles on the microstructure of soils was investigated. The results indicate that in addition to stress state, resilient modulus is significantly influenced by F-T cycles. For unmodified SC, the resilient modulus continually decreases with increasing F-T cycles. As for the modified soil, the resilient modulus decreases sharply after the first F-T cycle and then tends to be stable. The damage ratio and its fitting equation are effectively adopted to describe the variation characteristic of the resilient modulus after F-T cycles. As observed from SEM testing, the effect of F-T cycles on soils is to destroy the initial structure and increase the porosity of soils. It could be concluded that the microstructure change during F-T cycles is the main factor that results in the decrease of the resilient modulus.

Porous asphalt mixtures with steel slag (PAM-SS), as an eco-friendly and low-cost pavement material, are conducive to addressing the issue of urban floods and natural resource shortages. The primary objective of this paper was to explore the feasibility of the application of PAM-SS for seasonal frozen regions, and ascertain the optimal replacement percentage of natural aggregate. Steel slag coarse aggregate (SSCA) was used to replace basalt coarse aggregate (BCA) at four levels (25%, 50%, 75%, 100%) by equal volume. The volume characteristics, mechanical properties, low-temperature cracking resistance, water stability, and freeze-thaw (F-T) durability of the mixture were assessed. The results indicated that the low-temperature cracking resistance of the mixture was significantly enhanced and acoustic emission (AE) energy was uniformly released by the incorporation of steel slag. Furthermore, the porosity, permeability, Marshall stability (MS), and the resistance against water damage and F-T cycles were also significantly improved. Based on the experimental results, the complete replacement of natural aggregate is advisable to obtain an optimal overall performance.

Silty soil as a rich reserved subgrade fills in seasonally frozen regions of northern China, experienced at least one freeze-thaw (F-T) cycle each year. Many damages will occur after F-T cycles. In general, using cement to stabilise can alleviate that situation. Hence, a series of unconsolidated and undrained triaxial compression tests were conducted to evaluate the static properties (i.e. cohesion, internal friction angle, shear strength, stress–strain curves and resilient modulus) of cement stabilised silty soil. Meanwhile, the analysis of variance method was adopted to analyse the effects of multiple factors i.e. F-T cycles, confining pressures, water content and cement content on the resilient modulus. The results showed that the cohesion, shear strength and resilient modulus decreased with F-T cycles and water content, while increased with cement content, and tended to be stable after six cycles. The internal friction angle increased with cement content, whereas had no obvious regularities with F-T cycles and water content. The inclusion of cement could transform the stress–strain curves from strain hardening to strain softening, and inhibited the negative impact of F-T cycles and water content on resilient modulus. Based on the above analysis, $w_{\mathrm{opt}}$, 2% cement content and the mechanical property index after six F-T cycles could be used as guidance for actual projects. Moreover, an empirical equation for determining the resilient modulus was proposed and validated.

To reduce the impact of road ice and snow disaster, it is necessary to adopt low energy consumption and efficient active deicing and snow melting methods. In this article, three functional components are combined into a conductive ethylene propylene diene monomer (EPDM) rubber composite material with good interface bonding. Among them, the mechanical and electrical properties of the composite material are enhanced by using carbon fiber cloth as a heating layer. EPDM rubber plays a mainly protective role. Further, aluminum silicate fiber cloth is used as a thermal insulation layer. The mechanical properties of EPDM rubber composites reinforced by carbon fiber cloth and the thermal behaviors of the composite material in high and low temperature environments were studied. The heat generation and heat transfer effect of the composite were analyzed by electrothermal tests. The results show that the conductive EPDM rubber composite material has good temperature durability, outstanding mechanical stability, and excellent heat production capacity. The feasibility of the material for road active deicing and snow melting is verified. It is a kind of electric heating deicing material with broad application prospects.