Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

Eco-friendly pervious concretes containing fly ash (FA) and blast furnace slag (BFS) were prepared in this study. The compressive strength and hydraulic behaviors were investigated to explore the effect of replacement content of FA and BFS. Rheological tests of cementitious pastes were first conducted and the results showed that FA could increase the apparent viscosity and BFS did not change the rheology performance. Compared to traditional concretes, FA and BFS both decreased the compressive strength of pervious concrete at 28 d, while pervious concrete incorporated with FA and/or BFS presented comparable strength at 60 d. Compared to the control concrete mix, at the same replacement rate, FA changed the compressive strength more obviously than BFS. FA and BFS both decreased the effective porosity and permeability coefficient of pervious concrete. However, when the replacement rate (30%) was the same, concretes with ternary blends presented obviously larger porosity than binary blends. The relationships between porosity and permeability, and strength were also established.

Superhydrophobic surfaces have great potential for self-cleaning, anti-icing, and drag-reducing characteristics because of their water repellent property. This study demonstrates the potential application of coatings to protect architectures from detrimental atmospheric effects via a self-cleaning approach. In this research, a SiO₂-TiO₂-PDMS composite coating was prepared on the surface of building walls by the sol-gel method. Tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) were used as inorganic precursors, and polydimethylsiloxane (PDMS) was used as low surface energy substances. The effects of TEOS and PDMS content on microstructure, wettability, and self-cleaning performance of coating wall surfaces were investigated by conducting various tests, including scanning electron microscopy (SEM), X-ray energy spectroscopy (EDS), angle measurement, and Fourier transform infrared spectroscopy (FTIR). The results indicated that hydrolysis and condensation reactions of TEOS, TTIP, and PDMS were performed on the surface of the substrates, leading to a micro- and nano-structure similar to the surface of lotus leaves. When the molar ratio of PDMS to TEOS was 1:5, the static contact angle of the coating reached a maximum of 152.6°. At this point, the coated surface was able to resist the adhesion of particle pollutants and liquid pollutants, which could keep the walls clean and possess a good ability of self-cleaning. In conclusion, SiO₂-TiO₂-PDMS composite coating is potentially useful in wall protection applications with its hydrophobic and environmentally friendly superhydrophobic properties.