Basalt fiber has a great advantage on the mechanical properties and durability of reactive powder concrete (RPC) because of its superior mechanical properties and chemical corrosion resistance. In this paper, basalt fiber was adopted to modified RPC, and plain reactive powder concrete (PRPC), basalt fiber reactive powder concrete (BFRPC) and steel fiber reactive powder concrete (SFRPC) were prepared. The mechanical properties and freeze–thaw durability of BFRPC with different basalt fiber contents were tested and compared with PRPC and SFRPC to investigate the effects of basalt fiber contents and fiber type on the mechanical properties and freeze–thaw durability of RPC. Besides, the mass loss rate and compressive strength loss rate of RPC under two freeze–thaw conditions (fresh-water freeze–thaw and chloride-salt freeze–thaw) were tested to evaluate the effects of freeze–thaw conditions on the freeze–thaw durability of RPC. The experiment results showed that the mechanical properties and freeze–thaw resistance of RPC increased as the basalt fiber content increase. Compared with the fresh-water freeze–thaw cycle, the damage of the chloride-salt freeze–thaw cycle on RPC was great. Based on the freeze–thaw experiment results, it was found that SFRPC was sensitive to the corrosion of chloride salts and compared with the steel fiber, the improvement of basalt fiber on the freeze–thaw resistance of RPC was great.

Pervious concretes, such as sustainable pavement materials, have great advantages in solving urban flooding, promoting urban ecological balance, and alleviating urban heat island effect, due to its special porous structure. However, pervious concrete typically has high porosity and low strength. The insufficient strength and poor freeze-thaw durability are important factors that restrict its wide application, especially in seasonal frozen areas. Improving the strength and freeze-thaw resistance of pervious concrete will expand its application. Silica fumes, as an industrial by-product waste and supplementary cementitious material, play an important role in improving concrete performance. The objective of this paper was to study the effects of silica fumes on properties of sustainable pervious concrete. Silica fumes were used to replace cement with the equivalent volume method at different levels (3%, 6%, 9%, and 12%). The control pervious concrete and silica fume-modified pervious concrete mixtures were prepared in the lab. The porosity, permeability, compressive strength, flexural strength, and freeze-thaw resistance properties of all mixtures were tested. The results indicated that the addition of silica fumes significantly improved the strength and freeze-thaw resistance of pervious concrete. The porosity and permeability of all pervious concrete mixtures changed little with the content of silica fumes due to the adoption of the equal volume replacement method.

The urban environment is facing serious problems caused by automobile exhaust pollution, which has led to a great impact on human health and climate, and aroused widespread concern of the government and the public. Nano titanium dioxide (TiO₂), as a photocatalyst, can be activated by ultraviolet irradiation and then form a strong REDOX potential on the surface of the nano TiO₂ particles. The REDOX potential can degrade the automobile exhaust, such as nitrogen oxides (NO_x) and hydrocarbons (HC). In this paper, a photocatalytic environmentally friendly pervious concrete (PEFPC) was manufactured by spraying nano TiO₂ on the surface of it and the photocatalytic performance of PEFPC was researched. The nano TiO₂ particle size, TiO₂ dosage, TiO₂ spraying amount, and dispersant dosage were selected as factors to investigate the efficiency of photocatalytic degradation of automobile exhaust by PEFPC. Moreover, the environmental scanning electron microscope (ESEM) was used to evaluate the distribution of nano TiO₂ on the surface of the pervious concrete, the distribution area of nano TiO₂ was obtained through Image-Pro Plus, and the area ratio of nano TiO₂ to the surface of the pervious concrete was calculated. The results showed that the recommended nano TiO₂ particle size is 25 nm. The optimum TiO₂ dosage was 10% and the optimum dispersant dosage was 5.0%. The photocatalytic performance of PEFPC was best when the TiO₂ spraying amount was 333.3 g/m². The change in the photocatalytic ratio of HC and NO_x is consistent with the distribution area of nano TiO₂ on the surface of the pervious concrete. In addition, the photocatalytic performance of PEFPC under two light sources (ultraviolet light and sunlight) was compared. The results indicated that both light sources were able to stimulate the photocatalytic performance of PEFPC. The research provided a reference for the evaluation of automobile exhaust removal performance of PEFPC.

Acoustic emission (AE), as a nondestructive testing (NDT) and real-time monitoring technique, could characterize the damage evolution and fracture behavior of materials. The primary objective of this paper was to investigate the improvement mechanism of steel slag on the low-temperature fracture behavior of permeable asphalt mixtures (PAM). Firstly, steel slag coarse aggregates were used to replace basalt coarse aggregates with equal volume at different levels (0%, 25%, 50%, 75%, and 100%). Then, the low-temperature splitting test with slow loading was used to obtain steady crack growth, and the crack initiation and propagation of specimens were monitored by AE technique in real time. From the low-temperature splitting test results, SS-100 (permeable asphalt mixtures with 100% steel slag) has the optimal low-temperature cracking resistance. Therefore, the difference of fracture behavior between the control group (permeable asphalt mixtures without steel slag) and SS-100 was mainly discussed. From the AE test results, a slight bottom-up trend of sentinel function was founded in the 0.6–0.9 displacement level for SS-100, which is different from the control group. Furthermore, the fracture stages of the control group and SS-100 could be divided based on cumulative RA and cumulative AF curves. The incorporation of 100% steel slag reduced the shear events and restrained the growth of shear cracking of the specimen in the macro-crack stage. Finally, the considerable drops of three kinds of b-values in the final phase were found in the control group, but significant repeated fluctuations in SS-100. In short, the fracture behavior of PAM under low temperature was significantly improved after adding 100% steel slag.

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.

With the development of urbanization, pervious concrete has been increasingly used in urban road pavement structures. The objective of this paper was to investigate the effect of stress levels and modifier (ground tire rubber and silica fume) on the fatigue life of pervious concrete and establish the fatigue equations with different survival probabilities. In order to improve the deformability of pervious concrete without sacrificing its strength, ground tire rubber and silica fume were added into pervious concrete. Two kinds of pervious concrete, control pervious concrete and ground tire rubber and silica fume modified pervious concrete, were made in the laboratory. The pervious concrete beam specimens of 100 × 100 × 400 mm were casted, and the static flexural strength and flexural strain of the two kinds of pervious concrete were tested. The fatigue lives of two pervious concretes were tested using MTS fatigue testing machine under four different stress levels (0.85, 0.80, 0.75, and 0.70). The fatigue life was analyzed by two-parameter Weibull distribution. The parameters of Weibull distribution were determined by graphical method, maximum likelihood method and moment method. The Kolmogorov–Smirnov test was used to test the Weibull distribution and the fatigue equations under different survival probabilities were established. The results showed that ground tire rubber and silica fume modified pervious concrete had better deformability while ensuring strength compared to control pervious concrete. The addition of ground tire rubber and silica fume improved the fatigue life of pervious concrete. The two-parameter Weibull distribution was suitable to characterize the fatigue characteristics and predict the fatigue life of pervious concrete. Fatigue equations with different survival probabilities were a good guide for pervious concrete design.