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Asphalt aging holds responsibility for fatigue damage of asphalt pavement. Incorporation of nano-zinc oxide (nano-ZnO) as modifier into asphalt can effectively improve anti-aging property of asphalt. In this work, different dosage of nano-ZnO was added to original asphalt to prepare modified asphalt, and physical properties of nano-ZnO modified asphalt, including storage stability, penetration (25 °C), softening point and ductility (5 °C) were tested. Effect of nano-ZnO on the rheological properties of asphalt was studied by testing rheological properties of modified asphalt before and after aging. In addition, fatigue properties of asphalt with different nano-ZnO dosage were analyzed by linear amplitude sweep (LAS) test. Furthermore, anti-aging characteristics of nano-ZnO modified asphalt were characterized by thin film oven test (TFOT) and ultraviolet aging (UV-aging) test and mechanism was interpreted by UV–visible-infrared absorption test. The results show that nano-ZnO can influence penetration (25 °C), softening point, ductility (5 °C) and storage stability of asphalt. Nano-ZnO can improve complex shear modulus (G*), phase angle (δ) and fatigue performance. Addition of nano-ZnO can evidently improve anti-UV aging ability of asphalt and make asphalt show certain viscosity recovery during aging process. In addition, nano-ZnO has strong absorption characteristics to ultraviolet light with more than 95% absorption rate, which reflects its superiority as anti-UV aging modifier for asphalt. UV absorption of nano-ZnO modified asphalt is enhanced several times than that of original asphalt. Asphalt modified with reasonable nano-ZnO dosage possesses significant and evident anti-aging characteristics.

This work presents a deep-learning method to characterize the carbon fiber (CF) morphology distribution in carbon fiber reinforced cement-based composites (CFRC), predict the CFRC properties, and measure the contributions of different CF morphology distribution directly using X-ray images. Firstly, the components of CFRC in slices of X-ray images were segmented and identified using a fully convolutional network (FCN). Then the CF morphology distribution evaluation were conducted based on the results of the FCN. At last, the prediction of CFRC properties was realized using a cascade deep learning algorithm and CF morphology distribution results. The results showed that the FCN provided more reasonable segmentation results for each component in CFRC than traditional methods. CF clustered areas and CF bundles increased sharply with the increase of CF content, while uniformly dispersed CF areas showed the opposite trend. The cascade deep learning provided a method to predict the CFRC properties (e.g. resistivity and bending strength) using X-ray scanning images, which could also quantificationally measure the contributions of different CF morphology distribution to properties of the CFRC. Therefore, the proposed method could be regarded as a nondestructive and effective test for CFRC property evaluation.

Scanning electron microscope (SEM) is proven effective to analyze the morphology of carbon fibers (CFs) presenting in CFRC. However, the qualitative observation has limited contribution to the improvement of CF distribution as well as the properties of CFRC. In this work, a fully convolutional network (FCN) was developed to segment CFs from SEM images for quantitative CF distribution characterization. Three processes involved in the establishment of the FCN and its application for the CF distribution evaluation, which were: (a) generating a database including 560 CFRC SEM images in different scales; (b) designing, training, and testing an encoder-decoder network and other layers for the FCN; and (c) evaluating the CF distribution and analyzing the relationship between the CF distribution and the CFRC properties using segmentation results. The results showed that the FCN provided reasonable segmentation results for CF clusters with the 0.94F-Measure, 0.92 recall, and 0.96 precision, respectively. The FCN had stable segmentation results under different SEM magnifications. The FCN-based method was proven effective to segment CF clusters in real time, which met the demand for continuous SEM observation. The continuous observation results indicated that the mechanical and electric properties of CFRC were improved by the improvement of the CF distribution.

The effects of cement and emulsified asphalt contents on the performance of cement-emulsified asphalt mixture were systematically evaluated, including the indirect tensile strength, compressive strength, modulus of resilience, tensile strength ratio, dynamic stability, maximum bending strain, and Cantabro loss. In addition, the mesoscopic images and void characteristics of cement-emulsified asphalt mixtures with different material compositions were obtained, using scanning electron microscopy (SEM) and computed tomography (CT). The results indicated that at a constant cement content of 3%, when the emulsified asphalt content increased from 6% to 9%, the indirect tensile strength, compressive strength, and modulus of resilience first increased and then decreased. At a constant emulsified asphalt content of 8%, when the cement content increased from 0% to 4%, the indirect tensile strength first increased and then decreased, and the compressive strength and modulus of resilience each reached its maximum at a cement content of 3%. The addition of cement significantly improved the high-temperature stability and moisture stability of the asphalt mixture but was not conducive to its low-temperature performance. In addition, a minimum Cantabro loss was observed at a cement content between 2% and 3%. The mesoscopic void structures formed in different cement and emulsified asphalt contents also significantly affected the mechanical properties and mixture performances.

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.

Carbon-fiber-reinforced cement-based composites (CFRC) have been considered as an innovatively functional civil engineering material for self-monitoring buildings, snow-melting pavement and smart pavement. However, the distribution of carbon fiber can significantly influence the performance of CFRC, especially their mechanical and electrical properties. The main purpose of this research is to explore the effect of carbon fiber distribution on mechanical and electrical properties of CFRC. For this purpose, the components in consecutive slices of Computed Tomography (CT) images were identified and segmented by using their grayscale thresholds. The typical morphology of each component in micro-graph of fracture surface was classified. The classification was used to verify the results identified by their grayscale in CT images. Indexes of planar distribution (Pd), spatial distribution (Sd) and volume factor were designed and calculated using 3D reconstruction model of the specimen. The resistivity, bending strength, bending fracture energy and compressive strength of specimens with different carbon fiber contents were tested. Finally, the grey entropy correlation analysis (GECA) was conducted to determine the effect of fiber distribution on the performances of CFRC. Results showed that four components contained in CFRC are the sub-mm pores, highly clustered area, clustered area and fiber sparse area. The volume fractions of pores (VP), highly clustered area (VH), and clustered area (VC) increase with the increase of carbon fiber content while the sparse area (VS) shows the opposite trend. The Pd and Sd increase with the increase of carbon fiber content. Sd has greater influence on the bending strength and toughness of CFRC. Volume factor plays a more important role on compressive strength and electrical resistivity of CFRC.

Bitumen material is inevitably affected by environmental factors in the process of use, which leads to bitumen aging or oxidation, thus accelerating the performance deterioration of asphalt pavement. However, the traditional aging method has carried out under a specific constant temperature, which cannot simulate the aging behavior of bitumen under dynamic thermal change. Therefore, three dynamic thermal aging processes at different temperatures were selected to simulate the aging process of bitumen under thermal dynamic change in this work. Thin-layer chromatography with flame ionization detection (TLC-FID), Dynamic shear rheometer (DSR), Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and Atomic force microscopy (AFM) were utilized to test the components, rheological properties, prominent functional groups and microstructure of bitumen under different aging conditions. The results show that with the increase of aging cycles, the content of saturates and aromatics components in bitumen decreases, and the content of asphaltenes increases obviously under the higher temperature range for aging cycles. Secondly, the aged bitumen gradually hardens and becomes brittle, especially under the dynamic thermal of the peak temperature of 200 °C, the deterioration of bitumen performance after 20 cycles exceeds the impact of TFOT for 15 h. In addition, for bitumen, dynamic thermal aging is also a thermal oxygen aging behavior, and the roughness and altitude of the bee structure decrease. Overall, this work provides some new ideas for the aging behavior of bitumen under dynamic thermal changes.

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.

Aggregate gradation greatly affects properties of cement emulsified asphalt mixture (CEAM). In this work, an aggregate design based on fractal theory method (FTM) was put forward and trial calculation method (TCM) was adopted to design aggregate gradation of the mixtures. Properties of the mixtures, Marshall stability and splitting strength, were adopted as indexes to evaluate effects of the two methods. In addition, other properties of the mixtures such as, voids in mineral aggregates, porosity and residual stability of the mixtures were carried out to verify effects of the two methods. Furthermore, the gradation obtained by the two methods was simulated based on partical flow code in two dimension (PFC2D). The results show that the aggregate with the optimum gradation possesses dense skeleton structure and excellent stability. Particle contact force is relatively uniform distribution. Besides, voids in the mineral aggregate, porosity and residual stability of the mixture designed by FTM were superior to that designed by TCM. It was confirmed that the aggregate gradation design method with fractal model established in this work is reasonable and effective to improve strength of cement emulsified asphalt mixture.

Polymers have been used in cement materials for a long time. Notably, the polymer usage has a significant impact on cement hydration. In this work, the influences of interaction between cement and ionic paraffin emulsions (i. e., anionic paraffin emulsion (A), cationic paraffin emulsion (C), and nonionic paraffin emulsion (N), respectively) on cement hydration were experimentally investigated by calorimetry, UV–Vis spectroscopy measurement, depletion measurement, and XRD measurement, in which the hydration rate, hydration degree, and evolution of hydration products were assessed. Results reveal that anionic and cationic paraffin emulsions exhibit stronger hindrance effects to hydration kinetics than nonionic paraffin emulsion by comparison of b value based on the factorial design system. In addition, the stronger the adsorption between ionic paraffin emulsions and cement (decrease in absorbance; increase in adsorption ratio), the lower the hydration rate, hydration degree and the main diffraction peak intensity of hydration products. Meanwhile, the comparison of absorbance, adsorption ratio, and the main diffraction peak intensity of hydration products shows that anionic and cationic paraffin emulsions have strong adsorption on the surface of cement grains and/or cement hydration products, and have a strong hindrance on the dissolution of tricalcium silicate and the formation of portlandite and ettringite.

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.

Chloride salts are the most commonly used chemicals that serve as snow-melting agents for winter highway maintenance due to their abundance and low cost. However, the heavy use of chloride-based deicers has caused a series of environmental problems, because the deicers are directly spread on the pavement surface before snowing. Therefore, how to decrease the damage of chloride salts on pavement and environment is very important. Thus, introduction of the deicer into the asphalt mixtures and making the deicer slow release has brought a recent scientific and industrial interest. In this work, salt-storage aggregates (SSA) were innovatively prepared. Asphalt mixtures incorporating 0%, 5%, 10%, 15% and 20% SSA by volume as limestone aggregates (LSA) were prepared and their engineering properties were tested, such as high temperature stability, crack resistance at low temperature and water stability. In addition, salt-release performance of asphalt mixtures with SSA was investigated. Finally, field snow-melting test was conducted by outdoor experiments of the asphalt mixtures. The results show The SSA possesses excellent water stability, high mechanical strength and salt-storage function. The properties of asphalt mixtures with SSA can meet the requirements of specification, but the influence of SSA on water stability of asphalt mixtures should be noticed. The electrical conductivity of asphalt mixtures increases with the increase of SSA content. Salt precipitation amount per unit area increases and then gradually becomes stable with the increase of soaking time. Salt precipitation amounts from asphalt mixtures increase with the standing time and the SSA content. The asphalt pavement with SSA can possess satisfied snow-melting performance in reference to the simulated field tests.

Absorption between cement and emulsified asphalt enormously influences properties of cement emulsified asphalt mixtures. However, it is difficult to evaluate the absorption performance both quantitatively and morphologically. Therefore, ultraviolet–visible (UV–Vis) spectrophotometer was adopted to investigate the adsorption performance quantitatively and the adsorption rate was obtained successfully in this work. In addition, a viscometer was employed to test the viscosity variations of cement and emulsified asphalt binders. A Zeta potential analyzer was used to monitor the surface potential changes of cement asphalt particles in the binders with different cement contents. Scanning electron microscope (SEM) and polarizing microscope (PM) was used to capture the microcosmic images of the binders morphologically. Finally, the absorption process was simulated and the adsorption kinetic model was established. The results show that the initial viscosity of the binders increases with the increase of cement content and the standing time. The 800 nm wavelength is optimal for measuring absorbance between emulsified asphalt and cement. Adsorption rate increases with the increase of cement content and the standing time. The simulated absorption process consists of four stages, which are trigger absorption (Stage I), agglomeration absorption (Stage II), membrane absorption (Stage III) and stable absorption (Stage IV). The adsorption kinetic model can be adopted to quantitatively evaluate the adsorption rate between cement and emulsified asphalt with different cement content and standing time.

Ice on wind turbine blades, high-voltage transmission line and aircraft wing is a serous problem in winter, which causes much losses of energy. There is always a strong demand for de-icing techniques that are effective, low in energy consumption, lower cost and reliable operation. Ultrasonic de-icing, as an new de-icing technique, attracts more attention due to its energy-saving, simplicity, lower expenses, good applicability and no pollution produced to environment. In this paper, recent progress on ultrasonic de-icing technique is summarized in view of wind turbine blade de-icing, high-voltage transmission line de-icing and aircraft wing de-icing. In particular, a plier-shaped device invented by a college student in China for high voltage transmission line ultrasonic de-icing is introduced. This device has won China national patent and been effectively put into practical use. Finally, the miniaturization of ultrasonic generator is proposed. The purpose of this paper is to provide theoretic and experimental support for the widespread application of ultrasonic de-icing technique.

Mixing methods can significantly influence dispersion of carbon fibers in cement-based composites. In this work, pre-mixing method (carbon fibers were added before cement) and after-mixing method (carbon fibers were added after cement) were adopted to prepare carbon-fiber-reinforced cement-based composites (CFRC). X-ray computed tomography (CT) was used to obtain the cross-sectional images of successive layers in the composites. Scanning electron microscope (SEM) was adopted to capture microstructure images of the composites. The CT images were continuously identified through their grayscale peaks. The sub-mm pores were separated from carbon bundles to improve the accuracy of the identification results. Two-dimensional (2D) dispersion characteristics of two different mixing methods were quantitatively analyzed by extracting pixels area of each component. Meanwhile, three-dimensional (3D) models were established by means of optimized CT images to obtain the volume fraction of carbon fiber bundles. The results show that the average areas of uniformly dispersed area, which obtains through pre-mixing method, are higher than those with after-mixing method. The dispersion effect of pre-mixing method is superior than that with after-mixing method. In addition, the volume fraction of carbon fiber bundles in specimens prepared through pre-mixing method was lower than that prepared by after-mixing method. Thus, the contrast resolution of X-ray CT system can recognize materials with over 0.3% density difference in CFRC; and the pre-mixing method is recommended in the preparation of carbon-fiber-reinforced cement-based composites.

Cement emulsified asphalt mixtures are widely used as construction and building materials in pavement engineering and high-speed railway engineering. Consequently, engineering properties of the mixtures have been paid more attention, which can be enormously affected by variations of aggregate gradations and binder (emulsified asphalt and cement) contents. Therefore, the objective of this study was to evaluate the effects of aggregate gradations and binder contents on engineering properties of the cement emulsified asphalt mixtures. Three aggregate gradations were designed to calculate fractal dimension values based on fractal geometry. Two binders (emulsified asphalt and cement) and six contents were utilized to prepare the mixture specimens. Engineering properties of the mixtures were tested in laboratory, such as high-temperature stability, cracking resistance properties, moisture susceptibility and adhesion characteristic. In addition, scanning electron microscopy ( SEM ) and optical microscope ( OP ) were adopted to conduct a microstructure analysis of cement emulsified asphalt mixtures. The results showed that a given aggregate gradation was proved to have a specific fractal dimension value. Gradation with great fractal dimension values represented high surface irregularity, but didn’t always get good mechanical properties. The reasonable aggregate fractal feature and addition of cement both improved the high temperature stability of cement emulsified asphalt mixtures. Indirect tensile strength and moisture susceptibility were mostly affected by aggregate gradations and binder dosages. The Cantabro loss index was mainly dependent on aggregate gradation other than emulsified asphalt and cement contents. Reasonable aggregate gradation fractal and suitable binder contents jointly played an importance role in improving performance of cement emulsified asphalt mixtures.

Ordinary cement mortar is a widely used structural material. However, its microwave absorbing ability is very weak due to the lack of magnetic and electrical conductive components. Copper slag is a by-product produced from copper smelting, which possesses excellent magnetic properties. In this paper, ordinary cement mortar specimens incorporated with copper slag were prepared. The electromagnetic (EM) parameters were determined by a network analyzer in 8.2–12.4 GHz frequency ranges. The reflectivity of the mortars against EM wave was evaluated through an arch reflectivity testing system in the same frequency ranges. The skin depth and compressive strength of mortars were calculated and tested, respectively. Results show that both the real and imaginary parts of permittivity increase with the increase of copper slag content and over 30% copper slag contents can evidently improve the permittivity of the mortars. Meanwhile, permeability of the mortars is evidently improved in the frequency ranges with the addition of the copper slag. The reflectivity values of the copper slag-filled mortars tend to decrease and then increase with the increase of copper slag contents. The minimum reflectivity reaches −13.4 dB and the reflectivity below −10.0 dB can be obtained in the frequency range of 8.2–8.4 and 10.4–10.9 GHz representing 90% absorption when the copper slag content is 50%. Over copper slag content can make the mortar not absorb but reflect the EM microwave. Skin depth decreases with the increase of microwave frequency and copper slag content. The mortars with 50% copper slag content exhibit higher compressive strength value, as well as better microwave absorption performance.

This paper introduces a study of characterizing hydration and dry shrinkage behavior of cement emulsified asphalt composites (CEACs) through a deep-learning framework. The deep-learning framework consisted of two parts: generative adversarial networks (GANs) and deep neural networks (DNNs). The GAN part was first developed to map the design parameters of a CEAC to its X-ray powder diffraction (XRD) spectrum and scanning electron microscope (SEM) images. The DNN part was then designed to predict the dry shrinkage behavior of the CEAC based on its design parameters and the outputs of the GAN part. Finally, the effectiveness of the deep-learning framework was tested by 36 groups of CEACs. The results showed that the outputs of the GAN part, synthetic XRD spectrums and SEM images, were close to the measured data. Thus, the synthetic data were capable of characterizing the hydration processes and the microstructure of the CEACs. The DNN predicted the dry shrinkage ratios of the 36 groups with a 2.70% average error, demonstrating its high and stable precision. The feature vectors in the DNN provided a new method to characterize the effects of the design parameters on the dry shrinkage ratios. From the distribution of the feature vectors in a two-dimension space, we found that the curing time had the most significant effects on the dry shrinkage ratios, followed by the aggregate grading and the contents of cement and emulsified asphalt.

Superabsorbent polymer (SAP) has been considered as the most promising internal curing material due to its excellent internal curing efficiency. SAP type and particle size are important factors influencing the performance of cement-based materials. In this paper, cement paste was prepared by incorporating swollen SAP-SA and SAP-AA (sodium acrylate type of polymer and acrylic acid of polymer) with different particle sizes, 100 mesh, 120 mesh, 140 mesh, 170mesh, and 200 mesh, respectively. Firstly, the moisture diffusion areas of SAPs were compared and analyzed at different ages, and then the effect of the moisture released from SAPs on the mechanical properties, micro-hardness, and hydration was characterized and investigated. The results indicate that the 28-day moisture diffusion area of per gram of dry SAP-SA swollen with red ink in testing cement paste is about 40.3 cm2 to 50.8 cm2, while for each gram of dry SAP-AA, the 28d moisture diffusion area in testing cement paste is about 52.0 cm2 to 59.6 cm2. The cement pastes with SAP-SA and SAP-AA presents the higher 28d compressive strength at particle sizes of 140 mesh and 200 mesh, respectively. For the SAP-SA and SAP-AA of the same particle size of SAP-SA and SAP-AA, the incorporation of SAP-AA is more beneficial to the development of 28-day compressive strength and internal curing water diffusion of specimen than that of SAP-SA. The microhardness values of the specimens are closely related to the cumulative step length. The average crystal size of alite in the specimen containing SAP-AA200 is smaller than that in the specimen containing SAP-SA200.

“Black pollution” waste rubber tire powder is added to original asphalt to prepare rubber powder modified asphalt, which can not only solve the pressure of waste rubber tire on environment, but also improve the performance of asphalt pavement. However, the poor compatibility between rubber powder and original asphalt can weak the improvement effect of rubber powder on asphalt due to the strong network structure of rubber particles. Therefore, tetraethyl orthosilicate (TEOS) was introduced to pre-modify waste rubber powders in this work. And then the rubber powder modified asphalt (RPMA) was prepared and its physical properties, rheological properties and microstructures were investigated and characterized. Storage stability test, Fourier transform infrared spectroscopy working in mode of attenuated total reflectance (FTIR-ATR) and environmental scanning electron microscope (ESEM) were used to analyze effects of TEOS on storage stability of rubber powder. Influences of TEOS on physical properties of rubber asphalt were analyzed by softening point, penetration and ductility at 5 °C and combined with nuclear magnetic resonance (NMR) of 29Si. Finally, rheological property test and gel permeation chromatography (GPC) were used to analyze the mechanism of TEOS on rubber asphalt. The results show that the physical and rheological properties of RPMA are evidently improved. However, excessive TEOS can reduce the physical and rheological properties of RPMA. In addition, the proportion of macromolecule and micro molecule of RPMA first decreased and then increased with the increase of TEOS dosage. However, the molecular weight of RPMA increases. The network structure of Si-O-Si is intertwined with the network structure of rubber powder itself. Finally, the reasonable dosage of TEOS in RPMA can be determined through comparing properties of RPMA with different TEOS dosage.

Recycled aggregate (RA) will inevitably carry corrosion media, primarily due to the parent concrete suffered long-term sulfate attack. In this paper, the RA was replaced by a self-made mortar rod immersed in a Na2SO4 solution to investigate the internal transport and corrosion behaviors of sulfate corrosion media carried by RA in concrete. Four parameters, namely, cementitious materials of the mortar rod, corrosion concentration of the mortar rod, water-cement (W/C) ratio of the cement mortar, and cementitious materials of the cement mortar, were considered. The content of sulfate ions and depth of the sulfate ions diffusion were measured. Test results showed that when the corrosion concentration was higher than 5%, the migration distance and SO42− content increased significantly. Similarly, when W/C exceeded 0.6, the migration distance and SO42− content also increased significantly. The addition of fly ash and granulated blast-furnace slag could significantly inhibit the transport of sulfate ions in cement mortar. Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD) analysis results showed that the corrosion products were mainly ettringite and gypsum. The closer the distance to the mortar rod, the more the sulfate ions diffused into the cement mortar and the more corrosion products were obtained.

Low adhesion between emulsified asphalt mortar and aggregate can enormously result in poor properties of emulsified asphalt mixture. The adhesion performance can also be directly influenced by the viscosity of cement emulsified asphalt mortar (CEAM). In this work, Brookfield viscometer was used to test the viscosity of CEAM with different cement content, temperature and mixing time. Then, influence degree of each factor on viscosity was determined by gray correlation analysis (GCA) and significance test. Furthermore, dynamic mechanical analysis (DMA) was used to quantitatively evaluate the adhesion between CEAM and aggregate. Besides these, scanning electron microscope (SEM), energy dispersive X-ray (EDX), alkali content test, Fourier transform infrared spectroscopy (FT-IR) were adopted to analyze the interaction between cement and emulsified asphalt. The results show that the viscosity of CEAM increases with the increase of the cement content, mixing time and temperature. The cement content has the highest effect on the viscosity of CEAM, followed by mixing time; and temperature has a lowest effect. When the cement content is less than 50%, hydration products in the mixture can improve the fatigue life of CEAM. While it is higher than 50%, the adhesion is weakened and the fatigue life is shortened. Cement hydration and asphalt emulsion demulsification can mutually promote, which generates a network structure and improves the adhesion performance of CEAM to aggregate.

Natural magnetic components in magnetite are outstanding microwave absorbers, which can be used in asphalt pavement for deicing practice. Therefore, asphalt mixtures containing magnetite aggregate as microwave absorber for different replacements of conventional basalt aggregate were prepared in this work and their deicing characteristics were studied in laboratory. Properties of asphalt mixtures incorporated with magnetite and basalt aggregates were tested, respectively. Microwave heating efficiency ( MHE ), microwave reflection and microwave deicing time ( MDT ) tests of asphalt mixtures were conducted. In addition, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were adopted to conduct microscopic analyses. The results show that asphalt mixtures with magnetite aggregate present better performances at high temperature compared to those containing basalt aggregate with the same content, even though slightly lower water and temperature resistance are observed. The MHE of magnetite aggregate is 6.15 times that of basalt aggregate. The minimum reflectivity value of asphalt mixtures containing 80% magnetite content reaches −11.3 dB at 2.45 GHz frequency. Suitable magnetite content can decrease microwave reflectivity and improve microwave absorbing ability. The MHE of asphalt mixtures increases with the increase of magnetite contents when magnetite content is below 80%. Optimum magnetite aggregate content can evidently shorten the MDT . However, the MDT increases with the decrease of surrounding temperature. In a word, magnetite can be used as aggregates and microwave-absorbing materials in asphalt mixtures to achieve microwave deicing function.

Magnetite tailings (MTs) are waste generated from magnetite processing, which not only occupy lots of land, but also result in severe pollution to the surroundings. In this paper, the MTs were used as a substitution of limestone (LMs) aggregate in asphalt mixtures. Water boiling and residual Marshall stability tests were conducted to study asphalt-aggregate interface adhesion, which was improved by hydrated lime (HL). The effects of MTs on high temperature property, low temperature property and water stability property of asphalt mixtures were evaluated respectively through some indexes, such as dynamic stability, splitting strength at low temperature and freeze–thaw splitting strength ratio. In addition, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Infrared spectrometer (IR) and Zeta potential were also adopted to analyze the mechanism. The results show that there are not heavy metal elements and toxic pollution threats in MTs. The HL can improve the asphalt-aggregate interface adhesion and the water stability of the asphalt mixtures with MTs. MTs can improve the high temperature property and slightly decrease splitting strength at low temperature of asphalt mixtures. Freezing-thawing splitting strength ratio increases with the increase of MTs, which is greatly higher 80% requirement in the Chinese specification. Therefore, the asphalt mixtures containing MTs present excellent properties and MTs can be widely used as substitution of natural aggregates in asphalt mixtures for pavement engineering.

The foaming performance of porous cement slurry (PCS) foamed by H 2 O 2 was greatly affected by types and dosages of catalysts. In this paper, KMnO 4 was adopted as catalyst to the H 2 O 2 foamed PCS. The influences of the catalyst were investigated through the apparent density and coefficient of thermal conductivity (CTC) of each H 2 O 2 foamed PCS under different water to cement ratios (w/c ratios). The catalyst’s contribution degree to foaming effect (CDFE) in cement slurry was compared to the control group. The geometrical factors of pores in PCS were obtained through digital image processing technique. Morphology and components of PCS were analyzed with Scanning Electron Microscope and X-ray Diffraction, respectively. The results show that KMnO 4 can exert excellent catalytic effect in H 2 O 2 foamed PCS. The Portland cement in PCS can hydrate as normal. KMnO 4 displays higher contribution degree to foaming effect for the slurry with higher w/c ratio. Therefore, increasing the amount of KMnO 4 catalyst under high w/c ratio is more helpful for the foaming effect than under low w/c ratio. The pores in cement slurry with KMnO 4 catalyst are more regular and the slurry with catalyst possesses higher porosity than the control group.

Water-retentive asphalt concrete (WRAC), produced by incorporating water-retentive slurry (WRS) into porous asphalt concrete (PAC), could significantly reduce the surface temperature of pavements and is currently considered a promising tool for alleviating urban heat island effect. Based on laboratory test and microstructural analysis, the present study investigated the effects of varying the proportions of ground granulated blast furnace fly ash, calcium hydroxide and mixing water amount on workability of fresh WRS. In addition, the water absorbing capacity, compressive strength and flexural strength of the cured (hardened) WRS were determined. The microstructures of hardened WRS were examined using scanning electron microscopy in order to better understand the effect of hydration level and pore structure on the water absorbing capacity and mechanical properties of hardened WRS. The results showed that materials composition have significant effects on the water absorbing capacity, compressive strength and flexural strength of hardened water-retentive slurry, as well as the workability of fresh WRS. WRAC showed good moisture resistance, rutting resistance and low deformation resistance comparable to the control PAC. However, the use of WRAC resulted in a temperature drop of about 10 °C compared to the control PAC.

Superabsorbent polymer (SAP) is becoming the most promising internal curing material for cementitious materials. However, commercial SAP products, most of which are designed for hygiene products, controlled drug release, and agriculture, usually impair the strength of cementitious materials. In view of this, a novel type of poly(acrylic acid-co-acrylamide) SAP composites based on modified metakaolin (MK) was prepared for cementitious materials in this work. Modified MK, acrylic acid (AA) and acrylamide (AM) were polymerized by initiating of ammonium persulfate (APS). The kinetics characteristics of the fabricated SAP composites were studied by absorption and desorption in different solutions. The microstructures and phase compositions of SAP composites, as well as the mechanical properties of SAP-modified cement mortar were characterized by a suite of complementary techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and compressive strength test. Results show that the modification of silane coupling agent (SCA) and xanthan gum (XG) can increase the recombination degree between MK and copolymers. The water retentions of self-developed SAP composites, SAP-N1 and SAP-N2, are much better than those of two commercial SAPs in alkaline solution and cement filtrate, respectively. The maximum absorbency of SAP-N2 in sodium hydroxide solution is even greater than that in tap water. When SAP saturated with absorbed tap water is placed in saturated lime water, SAP-N2 can release only 0.49% water at a 4 h soaking period. Furthermore, either of the commercial SAPs has negative effects on the strength of cement mortar at 7 d and 28 d curing ages, while compared with the reference mortars, the incorporation of the SAP-N2 increases the 28 d compressive strength of the mortars by about 8% to 16%.

As the combinatorial space of a composite is virtually infinite and cannot be explored completely, a deep-learning method was proposed for high-throughput fiber-reinforced cement-based composites (FRC) design. First, a deep hierarchy network was developed to measure the relationship between the experimental variables and the FRC properties. A gradient-based high-throughput method based on the deep hierarchy network was then proposed to design FRCs, which were expected to have one or more certain properties. At last, a fine-tuning method was employed to guarantee its transferability for all types of FRCs. The results showed that the proposed method was able to design cement-fiber-water-curing-aging systems for carbon fiber reinforced cement-based composites (CFRCs). The fine-tuning method could transfer the CFRC model to design other FRCs. Thus, the proposed method showed promise for releasing the composite material property optimization from labor-consuming and low-efficiency laboratory tests.

Many researches and field applications have proven that binders modified with ground tire rubber (GTR) can significantly improve rutting resistance potential and durability of asphalt pavement. However, GTR modified asphalt binder has higher viscosity and poorer hot storage stability than base one resulting in construction troubles, such as more energy consumption, extra stirring, reduction in asphalt mixtures performance and etc. The objective of this study was to investigate the engineering and rheological properties of binders prepared with microwave preprocessed GTR at high service temperature, medium temperature, and low temperature, respectively. The experiment included two particle sizes of GTR and five microwave preprocessing radiation intensities. The dynamic shear rheometer (DSR), force ductility test (FDT) and hot storage test were performed to evaluate the effect of radiation intensities and particle sizes of GTR on the engineering and rheological characteristics from low to high temperature. The test results show that microwave preprocessed GTR modified binders presented a reduction trend in composite viscosity, as well as rutting resistance potential after exposing to microwave radiation. In addition, fatigue and low temperature tension properties were jointly affected by microwave radiation intensities and GTR particle size. Otherwise, lower phase separation tendency compared with binder modified with GTR without microwave radiation was observed in this study. Thus, comprehensive consideration of radiation intensities and GTR particles sizes were recommended to apply in the field.

In this paper, the mechanical and damping properties of concrete modified with lightweight aggregates (LAs) presaturated polymer emulsion were investigated. The effect of four variables, namely, LA type, maximum LA particle size, LA presaturated different polymer emulsions, and the sand ratio of concrete, on the mechanical and dynamic behavior were analyzed. Test results indicated that the damping ratio of concrete prepared using shale aggregates was lower than that of concrete prepared using clay aggregates, but has higher mechanical properties. The mechanical and damping properties of concrete decreased when the maximum LA particle size increased, especially after the particle size exceeded 20 mm, at which decreasing tendency became obvious. Concrete modified with LAs presaturated styrene-acrylic polymer emulsion had a higher damping ratio than concrete modified with LAs presaturated polyvinyl alcohol polymer emulsion. The damping ratio of concrete decreased as the sand ratio increased, and the compressive strength of concrete peaked at 40% sand ratio. The results of scanning electron microscope and energy dispersive spectrometer (SEM-EDS) showed that the free and constrained layers formed during the mixing process of concrete, which could provide damping capacity effectively and reveal the damping mechanism of the concrete.

Considering the groutability of porous media using cement slurry, the following phenomenon remains explained: although cement powder particles are smaller than the pore diameter of the porous medium to be grouted, cement slurry cannot be effectively grouted into the porous medium under some conditions. To better understand this unexplained phenomenon and the correlation between particle sizes and pore diameter, a focused beam reflectance measurement (FBRM) system was used to analyse the in-situ particle state characteristics of cement slurry. Further, the grouting depth of the slurry in sand columns was tested. Results showed that cement powder particles have a significant flocculation effect on the slurry and the chord size of the flocculent particles is 2–4 times greater than the powder particle size. The relationship between changes in chord size, water-to-cement ratio, and flocculation time were established. The primary factors affecting groutability were the presence of ultra-large flocculent particles, friction between large particles and pores, and particle arrangement within the pores. Finally, flocculent chord size can be employed as an index for evaluating groutability and develop a new criterion, as it particularly considers the blocking effect of large flocculent particles on porous media. This new and improved criterion can be used to predict groutability of cement grouts in sand as it more essentially reflects the groutability of porous media.

Effects of microwave heating time, microwave power, water-cement ratio (W/C) and bitumen-cement ratio (B/C) on early strength of cement bitumen emulsion mixture (CBEM) were studied in this work. Environment scanning electron microscopy (ESEM) and Fourier Transform infrared spectroscopy (FT-IR) were adopted to analyze microstructures and compositions of CBEM. The most important factors affecting CBEM strength were putting forward based on multiple linear regression analysis (MLRA) and grey correlation analysis (GCA). The results show that the total microwave energy is composed of microwave power and microwave radiation time. The higher the total microwave energy, the higher the surface temperature of CBEM. The effect of W/C on CBEM temperature is more significant than that of B/C. Microwave heating time and microwave power can evidently influence strength of CBEM. Microwave heating can promote cement hydration, which is beneficial to improve strength of CBEM. However, excessive microwave time can result in the decrease of CBEM strength. Temperature model based on MLRA can show linear correlation between different factors. Strength model shows quadratic correlation to microwave parameters. In summary, reasonable microwave heating is an effective technique to improve early strength of CBEM.

Ultrasonic oil production technique is characterized by high adaptability, simple operation, low cost and zero pollution. In this paper, the recent new high-power ultrasonic transducers for Enhanced Oil Recovery field in China are summarized. The application of high-power ultrasonic transducers for Enhanced Oil Recovery are also introduced in the view of preventing paraffin precipitation by ultrasonic wave, ultrasonic crude oil viscosity reduction, ultrasonic demulsification/dehydration, removing plug using ultrasonic wave and ultrasonic descaling/anti-scaling. Finally, installation speculations and operable speculations for ultrasonic oil production in offshore oil fields are given. the purposed of this paper is to provide important process parameters and technical support for future large-scale application of ultrasonic oil production technique.

Due to the strong piezoelectric effect possessed by lithium niobate and the fact that the adhesive bond of ice–substrate interface is relatively weak in shear, an ultrasonic de-icing technique that uses lithium niobate to design a light transducer for aircraft wing de-icing is proposed in this paper. The main contents of this paper are as follows: Firstly, a light de-icing lithium niobate transducer is designed to affix on the inner surface of the leading edge at the locations, where highest amount of ice accretion on the outer surface occurs. Secondly, the outdoor wing de-icing experiments are conducted to determine the optimal ultrasonic de-icing frequency. Finally, the design scheme of light-weight supersonic generator installed in the aircraft is presented. Research results show that this de-icing technique for aircraft wing de-icing is feasible, promising for further investigation.

This study evaluates the effects of two types of asphalt emulsion, anionic and cationic emulsions, on the properties of two types of cement emulsified asphalt mortar (CEAM), low-modulus CEAM and high-modulus CEAM, at varying asphalt to cement ratios (A/C). The study focused on the effects of emulsion on the properties of fresh CEAM mixes, including workability, cement hydration, dynamic shear modulus, and phase angle. The workability was evaluated using the flow table test. The cement hydration and dynamic shear rheometer (DSR) tests were performed to investigate the cement hydration development and viscoelastic properties of CEAM mixes. In addition, the uniaxial compressive strength was tested to examine the effects on the properties of hardened CEAM mixes. The laboratory test results show that the workability evidently decreased with the increase in A/C and the adoption of cationic asphalt emulsion. Increase in A/C ratio lowered the cement hydration rate in CEAM. Cationic asphalt emulsion and higher cement content made CEAM stiffer as it exhibited higher complex shear modulus. There was a significant reduction in compressive strength of the mortars with the increase in A/C ratio. Cationic asphalt emulsion was desirable for high-modulus CEAM because it could give CEAM a higher compressive strength than anionic asphalt emulsion at different ages.

To date, carbon fiber cement based composites are gaining popularity in the field of civil engineering. Dispersion degree of carbon fibers (CFs) in the composites plays a significant role in the property improvements. However, it is extremely challengeable to evaluate quantitatively the dispersion of CFs because of their random distribution and low contrast with cement paste. In this paper, X-ray computed tomography (CT) scanner was adopted to capture the images; Optical Microscope (OP) was used to determine the thresholds of different components and mathematical calculation was conducted to compare the degree of fiber dispersion. The dispersion coefficient was introduced to evaluate quantitatively dispersion of the CFs. The higher value of dispersion coefficient, the more uniform distribution the CFs. The value range of dispersion coefficient is concentrated from 84% to 94%. There is no rule for changes of dispersion coefficient with the changes of scanned slices. Meanwhile, variation coefficient was calculated as an index to effectively compare the fiber dispersion for the different scanned slice with the same dispersion coefficient. In addition, the lower variation coefficient of fiber dispersion, the more uniform distribution the CFs.

The present study investigated the mechanical properties of cement emulsified asphalt mortar (CEAM) as a damping material for ballastless high-speed rail track bed. CEAM has unique properties that differ from concrete and asphalt alone as this hybrid material combines the high strength of portland cement composites and the flexibility of asphalt materials. In this study, uniaxial compressive strength (UCS), indirect tensile (IDT) strength, tensile strength ratio (TSR), dynamic modulus and phase angle, and shrinkage were tested on CEAM samples at three different asphalt/cement (A/C) ratios. The cement hydration heat of the paste was measured and the microstructures of CEAM were examined to analyze the interaction between cement and asphalt and to explain its effect on the mechanical properties of CEAM. The results from this study show that CEAM exhibited loading rate- and temperature-dependent properties, indicative of a typical viscoelastic material. Cement could hydrate effectively and both cement and asphalt acted as a binder in the hybrid material as they were in cement or asphalt mix alone. The A/C ratio showed a significant effect on the mechanical properties and cement hydration heat of CEAM.

As a long-life road surfacing material, epoxy asphalt has many benefits such as high strength, excellent bonding properties, high temperature stability, and high resistance to low temperature cracking. With the increasing use of epoxy asphalt in orthotropic steel bridge deck pavements, there has been an urgent need for a fast, easy, and reliable maintenance method. Microwave heating provides a promising method for epoxy asphalt curing. This study explored the possibility of using microwave heating for epoxy asphalt curing and investigated the effects of microwave heating on chemical and physical properties of epoxy asphalt. An epoxy asphalt suitable for microwave heating was prepared, tested for its tensile properties, and characterized using thermal analysis, infrared analysis, and microscopy tests. The results showed that the epoxy asphalt cured by microwave heating had a better ductility than that cured by conventional heating. The fluorescence and scanning electronic microscopy (SEM) observati...