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Attainment of cycling comfort on urban roads encourages travelers to use bicycles more often, which has social and environment benefits such as to reduce congestion, air pollution and carbon emissions. Cycling vibration is responsible for the cyclists' perception of (dis)comfort. How asphalt pavement's surface characteristics relate to cycling comfort, however, remains undiscovered. In this study, the cycling vibration intensity on 46 sections of 24 urban roads was tested using a dynamic cycling comfort measure system while the cyclists' perception of vibration was identified via questionnaires; the cycling comfort was then defined based on the cycling vibration. To record the accurate pavement-tyre interface under a stable environment, a total of 19 pavement sections were scanned using a 3D digital camera. These 3D models were then 3D printed, which are used to conduct the pressure film test using a self-developed pavement-tyre interface test system. Three ranges of pressure films were adopted to characterize the pavement-tyre interface via 9 parameters, namely contact area (Ac), unit bearing area (Bu), stress intensity (Si), stress uniformity (Su), kurtosis (Sku), spacing (Spa), maximum peak spacing (Spmax), radius ratio (Rr) and fractal dimension (Fd), in consideration of the area characteristics, pressure amplitude, peak spacing and shape of the interface. Finally, the significant interface parameters were identified, and the regression model between interface parameters and cycling comfort was established. Results show that the cycling vibration was described to be ‘very comfortable’ when the human exposure to vibration level (awv) was less than 1.78 m/s2; ‘comfortable’ when the awv was between 1.78 m/s2 and 2.20 m/s2; and ‘uncomfortable’ when the awv was greater than 2.20 m/s2. The average stress on rear wheel-pavement interface is higher than that of the front wheel. Bu-0.6, Spa-0.6, and Fd-0.6 are significant to cycling vibration. The 2LW pressure film is recommended for use to measure the bicycle pavement-tyre interface. The recommended interface characteristics are less than 7 mm2 of the unit bearing area, 6 mm of average spacing and 2.38 of fractal dimension. Finally, dense asphalt mixture performs better in providing cycling comfort than the gap-graded asphalt mixture. Results of this study contribute to current knowledge on bike lane comfort and pavement design, the findings should be interested in cyclists, transport planners, and road authorities.

Driving safety deteriorated dramatically on ice-covered road pavement in winter. However, it is a challenge to remove thick ice layer from the pavement surface with conventional technologies. In this study, the microwave heating performance of asphalt mixtures containing steel wool fibers was tested. Firstly, the mechanism of pavement deicing using microwave was introduced. The effect of steel wool fiber on air void content of asphalt mixture is studied, and the fiber distribution is observed. The microwave heating performance of specimens with different types and contents of steel wool were tested under the temperature of −5 °C and −10 °C. The ice-thawing time was measured and the effect of initial temperature and ice thickness on the thawing time was evaluated. Finally, the heating uniformity and sustainability aspects of this technique were assessed. Results show that the optimal steel wool fiber contents for microwave heating of asphalt mixture are 0.3% of 000#, 0.6% of 0# and 0.9%% of 2#, respectively. The ice-thawing time of the pavement with an initial temperature of −10 °C is 9.3% (000#), 11.3% (0#) and 14.8% (2#) higher than that of −5 °C. In addition, every 1 cm increase in ice layer thickness requires 5.9% (000#), 7.7% (0#) and 13.0% (2#) increase in thawing time. A larger diameter of the steel wool helps to improve the heating uniformity. At last, the microwave heating capacity of specimens containing steel wool will not be significantly reduced by the repeated service in the first five winters.

Cracking problems are threats to durability and sustainability of high performance cement-based composites. Due to the complex behaviors of cement materials under various environmental conditions, accurate prediction of the cracks is very difficult. In this work, effects of noval thermo-sensitive polymer N-isopropylacrylamide (PNIPAM) on the cracking resistance of cement mortar were investigated. The micro structures of cement mortar and PNIPAM were characterized by environmental scanning electron microscopy (ESEM) and Fourier Transform Infrared Spectoscopy (FT-IR). The pulse velocity, water absorption and water content of cement mortar were tested to observe the inner structure changes of cement mortar with PNIPAM. Artificial neural network (ANN) technology was used to predict the cracking resistance of cement mortar with PNIPAM. The results show that PNIPAM is cross-linked macromolecule polymer with special thermo-sensitive characters of shrinkage at high temperature and expansion at low temperature. When the mixing temperature is lower than LCST of PNIPAM, it can expand and is soluble in water. However, PNIPAM can shrink and release water to cure the hardened mortar when temperature is higher than LCST due to the cement hydration heat accumulation. The proposed model built by ANN can be used to predict the cracking resistance of cement mortar. The model was further applied to evaluate the effects of different PNIPAM contents on the cracking performance of cement mortar. PNIPAM with suitable contents can decrease the internal deflects of cement mortar. The content of PNIPAM can be used below 1.2% of cement mass for the consideration of cracking resistance improvement of cement mortar.

As a new clean renewable energy, Perovskite solar cells (PSC) has become a research hotspot. The multi-step diffusion method can effectively control the composition and proportion of the precursor liquid, regulate the crystallization process and the final morphology of the perovskite film, thereby obtaining a smooth and dense high-quality perovskite film; The introduction of micro-Mg element makes the Fermi energy level of TiO2 electron transport layer move up, enhances conductivity, and reduces surface defect states. Correspondingly, after Mg doping, the series resistance of planar perovskite battery decreases, the electron transmission speed becomes faster, and the charge collection efficiency is improved under high bias voltage; In the process of deposition of perovskite film by one-step inverse solvent method, polystyrene (PS) is introduced to cover the surface of polycrystalline perovskite film and fill the grain boundary to form a protective layer covering single grain. On the one hand, PS coating can effectively inhibit the volatilization and phase separation of organic components in perovskite films at high temperature, and maintain the stability of film components and phase, on the other hand, PS coating can effectively prevent the corrosion of perovskite film by water, and improve the moisture stability and self-repair ability of the film. In addition, since the self-adhesive porous carbon has good flexibility, compressibility, and adhesion to the electrode, it can be applied to perovskite solar cells. After the pressure is transferred, the carbon counter electrode can form an excellent interface contact with the hole transport layer, which promote the interface charge extraction and solve the interface contact problem existing in carbon-based perovskite batteries for a long time. The purpose of the paper is to provide the basis for exploring the technology of PSCs preparation on a large scale.

Hot poured steel slag (HPSS) was adopted as microwave absorber to replace partial limestone aggregate to prepare asphalt mixtures in this work. Thermal transfer characteristics of asphalt mixtures through microwave heating (MH) were discussed. Firstly, the MH capacity of HPSS with different particle sizes were studied. Then, the morphology and element percentage of HPSS were characterized with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Subsequently, surface temperature, heating uniformity and thermal transfer characteristics were analyzed. The results show that HPSS has good microwave absorption capacity and the increment of HPSS in asphalt mixtures can increase the surface temperature. The surface temperature of asphalt mixtures with HPSS can be evidently influenced by microwave power due to the correlation between microwave energy and microwave power. Besides, the heating uniformity of asphalt mixtures decreases with the increase of HPSS content, which is mainly related to the spatial distribution and heat generating rate of HPSS. Finally, the thermal transfer characteristics of asphalt mixtures with HPSS are divided into three types according to thermal source intensity and thermal transfer efficiency. Overall, it can be used as functional asphalt mixtures to improve the sustainability of pavement because of the good microwave absorption performance of asphalt mixtures containing HPSS.

Under the dilemma of non-renewable natural resources shortage and environmental pollution issues, as a novel aggregate used in asphalt pavement, the application of steel slag is propitious to the improvement of the environment and the enhancement of economics. Meanwhile, steel slag has great potential for microwave heating as an excellent microwave absorbing material, which can contribute to remove the ice layer on the pavement. The primary objective of this work was to explore the feasibility of the usage of steel slag as the aggregate of asphalt mixtures for microwave deicing, and ascertain the most effective volume and particle sizes for partial replacement of conventional aggregate. The deicing mechanism of microwave heating pavement was firstly introduced. Then, the microwave heating capacity of steel slag with different particle sizes was tested and the surface elements distribution of steel slag was measured. In addition, the XRD test was conducted to analyze the material information of steel slag for its microwave heating capacity. Finally, the surface temperature, thermal conductivity and heating uniformity of asphalt mixture containing different steel slag content were tested. Results show that the particle sizes of 9.5 mm, 2.36 mm and 0.6 mm are considered as the most effective sizes. The thermal conductivity and microwave heating uniformity of asphalt mixtures basically decrease with the increase of steel slag content; while the surface temperature presents a contrary trend. Consequently, the suggested steel slag volume content is 40% and 60%; and the particle sizes of steel slag are selected as 9.5 mm, 2.36 mm and 0.6 mm. The comprehensive evaluation results on the supply sources, environmental hazard and cost of steel slag show great feasibility of its utilization in asphalt mixtures for microwave deicing, which is helpful to alleviate the supply shortage of natural aggregates and improve the safety of road traffic in winter.

“Waste materials” possess “new utilization” for that the application of copper slag (CS) instead of natural sand can impart excellent engineering properties and exceptional microwave absorption characters to cement-based composites. In this work, natural sand was replaced in volume by copper slag to design and prepare cement mortars with different copper slag contents (10%, 30%, 50%, 70% and 100%). The mechanical properties, workability, durability and microwave-absorbing characters of mortars were tested and evaluated by the response surface methodology (RSM) and grey entropy correlation analysis to perform a collaborative analysis; and finally, optimal copper slag content was recommended. The prediction model constructed by RSM shows that mechanical properties can be mostly optimized when the conditions were set to water/cement ratio of 0.6, copper slag content of 46% and copper slag fineness modulus of 2.77. Copper slag can obviously affect workability and durability of mortars, which can be mainly due to its irregular shape and low water absorption rate. Furthermore, the microwave-absorbing characters of mortars can vary with copper slag content. The mortar with 50% copper slag content achieves the minimum reflectivity and the maximum effective bandwidth. The roughness, water absorption and content of copper slag should be given priority when applied in microwave-absorbing building engineering. Copper slag makes a dominant contribution to mortars when its content reached 50%, which can be recommended as the optimal copper slag content incorporating into cement-based composites.

The key to the development of microwave deicing technology in asphalt pavement engineering is to improve the heating efficiency using less magnetite aggregate with regards to the aggregate resource shortage. In this work, four asphalt mixtures with different magnetite layer thickness (MALT) by volume of the limestone aggregate were prepared. The microwave heating capacity test of magnetite aggregate was carried out firstly. Surface temperature, heat distribution, radiation depth, deicing time, and thermal diffusion for asphalt mixtures were also investigated. Results show that 4.75mm–9.5 mm is considered as the most suitable sieve size according to its higher microwave heating efficiency (MHE) and the highest proportion in aggregate gradation. The reduction of MALT in asphalt mixture can significantly improve the MHE ascribed to higher thermal conversion and utilization, related to the lower microwave reflectivity and shorter propagation path of internal heat to the surface obtained through adjusting MALT. The heat distribution of asphalt mixture with thinner MALT was more unevenly, which can be mainly attributed to the higher heat generating rate. Besides, the heat generated by the upper layer can be quickly transferred to limestone aggregate layer and thus the heat depth can not be used to represent the depth of radiation. In addition, both MALT and initial temperature have effect on the heat diffusion. The reason behind the higher deicing efficiency for asphalt mixture with thinner MALT was owing to both higher MHE and higher heat transfer efficiency.