Aiming at the engineering problem of poor water stability of silt in the Yellow River area, a curing agent (SBCG) was prepared with steel slag, granulated blast furnace slag, and desulfurized gypsum as the main materials to improve and solidify the alluvial silt of the Yellow River. Taking the unconfined compressive strength and CBR as the main indicators, the water stability performance of SBCG-solidified silt was studied through water immersion tests. Meanwhile, the pore characteristics of the solidified silt were observed by Nuclear magnetic resonance (NMR). The results show that the addition of SBCG can obviously improve the engineering properties of silt soil. The standard curing strength is significantly improved with the increase of SBCG content, the guarantee rate of water immersion strength at 7d age is all greater than 80%, and the CBR after immersion still meets the requirements of subgrade strength. According to the change law of the strength of the solidified silt under different test conditions, the preferred dosage of SBCG is determined to be 6%∼10%. The pore structure characteristics are an important factor affecting the water stability of solidified silt. The large pore volume and the porosity of solidified silt decreased significantly with ages.

Based on comparative analysis of the performance of the coal gangue aggregate pavement base mixture before and after coal gangue strengthening, Coal gangue has high water absorption and is easy to disintegrate and pulverize in water, which is not conducive to the water stability, rigidity, and strength of a semi-rigid base. In view of this, in this paper, the process of organic composite inorganic strengthening coal gangue coarse aggregate is adopted. An alkali metal reinforcing agent is added, which can make the 7-day unconfined compressive strength of the full replacement rate coal gangue aggregate pavement base mixture reach 3.5–7.5 MPa. The road performance, such as dry-wet cycle, frost resistance, and splitting strength, has also been greatly improved so as to meet the technical requirements of high-grade highway base construction. It is in line with the strategic needs of the country to promote the carbon peak of the building materials industry and strengthen the comprehensive utilization of bulk solid waste.

Temperature segregation during the paving of asphalt pavements is one of the causes of asphalt pavement distress. Therefore, controlling the paving temperature is crucial in the construction of asphalt pavements. To quickly evaluate the road performance of asphalt mixtures during paving, in this work, we used unmanned aerial vehicle infrared thermal imaging technology to monitor the construction work. By analyzing the temperature distribution at the paving site, and conducting laboratory tests, the relationship between the melt temperature, high-temperature stability, and water stability of the asphalt mix was assessed. The results showed that the optimal temperature measurement height for an unmanned aerial vehicle (UAV) with an infrared thermal imager was 7–8 m. By coring the representative temperature points on the construction site and then conducting a Hamburg wheel tracking (HWT) test, the test results were verified through the laboratory test results in order to establish a prediction model for the melt temperature and high-temperature stability of y = 10.73e0.03x + 1415.78, where the predictive model for the melt temperature and water was y = −19.18e−0.02x + 98.03. The results showed that using laboratory tests combined with UAV infrared thermography could quickly and accurately predict the road performance of asphalt mixtures during paving. We hope that more extensive evaluations of the roadworthiness of asphalt mixtures using paving temperatures will provide reference recommendations in the future.

In order to better evaluate the construction quality of asphalt pavement, nondestructive testing techniques are used to inspect newly paved asphalt mixture pavement. The proposed system for the evaluation of asphalt pavement construction quality uses three-dimensional ground-penetrating radar (GPR) and a non-nuclear density gauge. The GPR and the non-nuclear density gauge test results were used to establish a dielectric constant–porosity model by fitting. This approach can more accurately determine the dielectric constant selection scheme of the GPR based on the average value of every 10 dielectric constant data points in the length direction of the radar antenna and every three data channels in the width direction. The GPR collected the dielectric constants of the road surface based on the total reflection method and used the average value of the local dielectric constant to evaluate the construction quality of the road. The non-nuclear density gauge used the local porosity to assess the construction quality of the road. It is recommended that the two testing schemes described above be used to evaluate the quality of asphalt pavement construction. They can provide theoretical guidance for future applications in practical processes.

钢渣作为炼钢产物之一,在中国利用率较低,将钢渣掺入沥青玛蹄脂碎石混合料中,可提高路用性能又能减轻对天然石料的开采力度.为了确定SMA-13沥青混合料的最佳钢渣掺量,采用等体积法将陈化钢渣替换石灰岩粗集料,制备了5种钢渣掺量的SMA-13沥青混合料,确定了各钢渣掺量的级配组成及最佳沥青用量,通过高温稳定性、水稳定性、低温抗裂性、体积膨胀性等路用性能验证,分析得出最佳钢渣掺量.结果表明:随着钢渣的掺入,混合料的高温稳定性和水稳定性均有提高,超过75％钢渣掺量时开始下降;沥青混合料的低温抗裂性和体积安定性随着钢渣掺入量的增加而下降,但都满足规范要求;钢渣的掺入可以提高混合料的动态模量;通过对以上性能分析,建议SMA-13沥青混合料的钢渣最佳掺量为75％.研究结果为将来钢渣在道路工程中更广泛的应用提供参考.

To study the in-situ response and performance of asphalt pavement, instrumenting pavement with a variety of sensors has become one of the most important tools in the field or accelerated load facilities. In the dynamic response collection process, engineers are more concerned with the load position strain of the pavement structure due to wheel wander. This paper proposes a method to obtain the load position and the strain at the load position when there is no lateral-axis positioning system based on multilayer elastic theory. The test section was paved in the field with installed strain sensors to verify and apply the proposed method. The verification results showed that both the calculated load position and load position strain matched the measured values with an absolute difference range of 5–60 mm, 0.5–2.5 με, respectively. The application results showed that the strain at the load position calculated by the proposed method had a good correlation with the temperature, as expected.

The silt in the Yellow River alluvial plain has low clay content, low cohesion and poor structure. Its stability has always been a difficult problem in the engineering field. In order to improve the engineering properties of the silt in the alluvial plain of the Yellow River, a new type of silt composite flexible curing agent was prepared by using sintered red mud and matrix asphalt as the main materials to comprehensively stabilize the silt. The aim of this study was to investigate the effects of sintered red mud-asphalt composite flexible curing agent on aged mechanical properties of treated silt, in which the replacement levels of the flexible curing agent below 10% by weight are compared. Apart from the compressive strength, the drying shrinkage, low temperature freeze-thaw and high temperature self-healing ability are measured. The test results show that the flexible curing agent has a positive effect on improving the mechanical properties of stabilized silt. The flexible curing agent series exhibit higher compressive strength, better water stability, resistance to freeze-thaw and high temperature self-healing ability, and lower drying shrinkage compared to silt and cement stabilized silt. The preferred dosage 4%~6% of the flexible curing agent is obtained by mechanical property analysis. The SEM images show that the incorporation of the flexible curing agent helps the silt form dense cementation and non-connected microporous structure, that is beneficial to the improvement of water stability and frost resistance. The asphalt component in the flexible curing agent can reorganize and diffuse in the soil, fill the internal pores and micro cracks, and realize the repair of soil damage and structural reinforcement.

In this paper, Co-based WC composite coating was prepared by laser cladding on the surface of high speed steel (HSS) tools damaged for numerical control machine tools. The results show that the interface metallurgical bonding between HSS substrate and repair layer is good without obvious defects. The repair layer is mainly composed of a Co-based FCC crystal structure and three types of carbides. The microhardness is about (1625 +/- 63) HV, which is 364.3% higher than that of the HSS substrate. The average friction coefficient is 0.65. The wear surface is relatively intact compared with the HSS tool. Cutting experiments show that the HSS tool with the Co-WC repair layer has lower O content on the rake face and better cutting performance.

Obtaining the required homogeneity, including uniform thickness and density, is very crucial for controlling the quality of flexible asphalt layers. Although non-destructive testing (NDT) methods are time-saving and less labor-intensive, they only provide indirect measurement data under testing area conditions and strongly depend on the explanations by prediction models. In this study, in terms of the three-dimensional air-launched Ground Penetrating Radar (GPR) technique, the dielectric constant of asphalt concrete base with dry conditions in pavements was detected and calculated by different methods (the Coring Method, Reflection Amplitudes Method and Common Mid-Point Method). According to the calculated dielectric constant, the thickness and density of asphalt concrete base were further calculated and assessed. Comparing with the Coring Method, the Common Mid-Point Method was recommended to calculate dielectric constants in order to obtain reliable thickness of asphalt pavement base. Among the Birefringence, Boettcher, Linearity indicator, and Rayleigh models, the Rayleigh model was suggested to predict the density, and the predicted density exhibited a good correlation coefficient with the measured one. Furthermore, by choosing these proper calculation methods, an assessment was successfully conducted to evaluate homogeneity of a constructed field pavement in practice.

To reduce the use of aggregates such as limestone and basalt, this paper used steel slag to replace some of the limestone aggregates in the production of SMA-13 asphalt mixes. The optimum content of steel slag in the SMA-13 asphalt mixes was investigated, and the performance of these mixes was evaluated. Five SMA-13 asphalt mixes with varying steel slag content (0%, 25%, 50%, 75%, and 100%) were designed and prepared experimentally. The high-temperature stability, low-temperature crack resistance, water stability, dynamic modulus, shear resistance, and volumetric stability of the mixes were investigated using the wheel tracking, Hamburg wheel tracking, three-point bending, freeze–thaw splitting, dynamic modulus, uniaxial penetration, and asphalt mix expansion tests. The results showed that compared to normal SMA-13 asphalt mixes, the high-temperature stability, water stability, and shear resistance of the SMA-13 asphalt mixes increased and then decreased as the steel slag content increased. All three performance indicators peaked at 75% steel slag content, and the dynamic stability, freeze–thaw splitting ratio, and uniaxial penetration strength increased by 90.48%, 7.39%, and 88.08%, respectively; however, the maximum bending tensile strain, which represents the low-temperature crack resistance of the asphalt mix, decreased by 5.98%. The dynamic modulus of the SMA-13 asphalt mixes increased with increasing steel slag content, but the volume expansion at a 75% steel slag content was 0.446% higher than at a 0% steel slag content. Based on the experimental results, the optimum content of steel slag for SMA-13 asphalt mixes was determined to be 75%.

The dynamic responses of a pavement structure to traffic loading is typically collected to predict pavement performance or in-service life. Researchers have primarily focused on using the maximum deviation from the peak strain responses to the conjoint valley responses for investigating the structural response of the pavement. However, the existing batch-processing program is not capable of identifying peak and valley responses from the low signal-to-noise-ratio (SNR) electronic signals. This paper explored the use of low-pass filtering and wavelet filtering to de-noise the strain signals for data pre-processing, and proposed the adaptive maximum energy ratio method and standard deviation method to isolate the foreground loading areas from the background noise of the strain responses. Finally, an automated data processing software was developed to precisely identify the peak and valley responses. This software provides a significant advancement to the current state of the practice in dynamic signal processing for pavement evaluation and performance prediction applications.

For highway maintenance, due to the restriction of security and the need to reduce the traffic delay, the pavement structure performance needs to be detected fast and accurate, to provide the design basis for the formulation and implementation of the maintenance plan. Rapid and nondestructive detection and diagnosis technology of the pavement structure is not only the currently practical needs and the direction of development of pavement maintenance of China, but also the major bottleneck problem restricting pavement maintenance of China. Especially the internal structure of the pavement, the detection and diagnosis are more difficult because of its invisible. Based on experience or the means of destruction efficiency and reliability of excavation is poor, lacking rapid, nondestructive, and effective detection method. According to the practical needs of the present, starting from the damage cause of disease and development mechanism of the road structure, a rapid detection and diagnosis of damaged pavement based on 3D ground penetrating radar is developed. Through many detections of different conditions in actual project, using common midpoint method (CMP) and three-dimensional radar chart of typical diseases method, the detection results of pavement structure are evaluated. The pavement distresses rapid detection, evaluation, and diagnosis methods based on 3D ground penetrating radar are developed.

The flexible pavement was facing Environment pollution and resource strain in the moment. KGO III (Karl Guunar Olhson III) flow mixing method is a new mixing method which can reduce the asphalt content and mixing temperature and prolong pavement service life. Its development, basic theory and mixing process were introduced in this paper. Two types of the gradation (AC dense-graded asphalt mixture), SMA (stone mastic asphalt), three normal size (13mm, 16mm) asphalt mixtures were mixed by conventional method and KGO flow mixing method. It is confirmed that the volume of AC which is mixed with KGO method is smaller than conventional mixing method while SMA present the opposite result. Furthermore, to the AC13, this paper analyzed its volume index, compacting curve and property parameters, refined the flow mixing method and adjusted the asphalt content by the orthogonal experiment and auxiliary test. An optimum parameters constitute was provided. The two kinds of asphalt mixture were used to carry on simple properties test. As a result, the optimum flow mixing method can reduce asphalt content, presents excellent water stability while keeping basic pavement performance. However, its high-temperature property is not performing as well as the conventional method.