Asphalt pavements in frozen regions are highly susceptible to damage induced by freeze-thaw cycles, during which microcracks initiate, propagate, and ultimately evolve into macrocracks. However, warm-mixed recycled asphalt mixtures (WRAMs) exhibit limited resistance to multi-stage fracture cracking. To address this limitation, basalt fibers (BFs) with various morphologies and dosages were incorporated into WRAMs to enhance their crack-resistance mechanisms. WRAM, chopped basalt fiber-reinforced WRAM (WR-CBF), and flocculent basalt fiber-reinforced WRAM (WR-FBF) were investigated under Mode I, Mode III, and mixed Mode I/III fracture modes. Specimens were subjected to 10 and 20 water and salt freeze-thaw cycles, followed by macroscopic edge-notched disk bend (ENDB) tests, mesoscopic acoustic emission (AE) analysis, and microscopic scanning electron microscopy (SEM) observations. The results indicate that WR-FBF with a basalt fiber content of 0.4% exhibits optimal crack resistance. Fracture resistance decreases with increasing freeze-thaw cycles, with salt freeze-thaw cycles causing more severe deterioration than water freeze-thaw cycles. Chopped basalt fiber provides more stable resistance to crack propagation across different fracture modes, whereas flocculent basalt fiber primarily enhances resistance to crack initiation, particularly under fracture mode I loading. SEM observations further indicate that FBFs enhance interfacial bonding and stress redistribution through adsorption, anchoring, three-dimensional network formation, and fiber pull-out mechanisms, thereby significantly improving the overall crack resistance of WRAMs.

In addition to reducing construction temperatures, incorporating warm mix additive into crumb rubber modified asphalt binder (CRAB) holds promise for enhancing adhesion and low-temperature properties. The low-temperature properties of surfactant-crumb rubber modified asphalt binder (S-CRAB) at various aging stages were conducted using the Bending Beam Rheometer (BBR) test and the Burgers viscoelastic model to determine the dissipated energy ratio and derivation of creep compliance. Surface free energy (SFE) analysis and contact angle test revealed enhanced adhesion and cohesion between S-CRAB and aggregates (sandstone, basalt, and limestone), with limestone demonstrating the best adhesion performance. In conclusion, the addition of surfactant improved the anti-aging performance, low-temperature properties, adhesion, and resistance to moisture damage of CRAB. Additionally, micromechanical properties and micromorphology, assessed using atomic force microscopy (AFM) with the Johnson-Kendall-Roberts (JKR) model, highlighted improvements in Derjaguin-Muller-Toporo (DMT) modulus, adhesion force, and micro work of adhesion. Notably, a correlation between contact angle and AFM results suggests that micro-mechanical properties directly influence macro-scale performance. These findings underscore the feasibility of applying surfactant-modified CRAB to improve asphalt durability.

This study systematically investigates continuous and discrete spectra methodologies for determining time-domain viscoelastic response functions (creep compliance and relaxation modulus) in asphalt mixtures. Through complex modulus testing of three asphalt mixtures (base asphalt mixture, SBS-modified asphalt mixture, and crumb rubber-modified asphalt mixture), we established unified master curves using a Generalized Sigmoidal model with approximated Kramers-Kronig (K-K) relations. Discrete spectra can be obtained by Prony series of Maxwell/Kelvin modeling, while continuous spectra derived through integral transformation produced complementary response functions by numerical integration. Comparative analysis demonstrated that discrete and continuous spectra methods yield highly consistent predictions of the relaxation modulus and creep compliance within conventional time scales (10-7-105 s), with significant deviations emerging only at extreme temporal extremities. Compared to discrete spectra results, material parameters (relaxation modulus and creep compliance) derived from continuous spectra methods invariably asymptotically approach upper and lower plateaus. Notably, the maximum equilibrium values derived from continuous spectra methods consistently surpassed those obtained through discrete approaches, whereas the corresponding minimum values were consistently lower. This comparative analysis highlights the inherent limitations in the extrapolation reliability of computational methodologies, particularly regarding spectra method implementation. Furthermore, within the linear viscoelastic range, the crumb rubber-modified asphalt mixtures exhibited superior low-temperature cracking resistance, whereas the SBS-modified asphalt mixtures demonstrated enhanced high-temperature deformation resistance. This systematic comparative study not only establishes a critical theoretical foundation for the precise characterization of asphalt mixture viscoelasticity across practical engineering time scales through optimal spectral method selection, but also provides actionable guidance for region-specific material selection strategies.

To investigate the dynamic mechanical properties of warm-mix steel slag-crumb rubber modified asphalt mixtures across wide- and narrow-frequency domains and evaluate the applicability of warm-mix technology, four distinct mixtures were prepared. The dynamic modulus characteristics under measured temperatures and frequencies were initially analyzed through complex modulus testing to elucidate narrow-frequency-domain mechanical behavior. Subsequently, leveraging the linear viscoelastic (LVE) theory and time–temperature superposition principle (TTSP), both the 2 Springs, 2 Parabolic Elements and 1 Dashpot (2S2P1D) mechanical element model and Modified Havriliak–Negami (MHN) mathematical model were established based on experimental data to characterize wide-frequency-domain dynamic responses. The results demonstrate substantial consistency in mechanical interpretation between narrow- and wide-frequency domain datasets, with enhanced information resolution achieved in wide-frequency analysis. Both models demonstrate comparable accuracy in characterizing the thermomechanical behavior of warm-mix steel slag-crumb rubber modified asphalt mixture across extended frequency and temperature ranges, while showing negligible performance discrepancies between the 2S2P1D and MHN formulations. Furthermore, both Cole–Cole and Black diagrams convincingly demonstrate the reliability of model predictions. This systematic investigation confirms the technical viability of warm-mix steel slag-crumb rubber modified asphalt mixture while establishing a dual-validated modeling framework for comprehensive performance prediction.

To characterize the quasi-brittle fracture behavior of highly heterogeneous asphalt concrete structures, it is essential to identify fracture parameters that are independent of specimen size and the crack-tip damage zone. This study develops a boundary effect model for determining size-independent fracture parameters-tensile strength, fracture toughness, and fracture energy-of Styrene-Butadiene-Styrene (SBS)-modified asphalt concretes. These parameters are directly derived from peak loads obtained in small notched three-point bending tests at -10 degrees C$$ {}<^>{{}<^>{\circ}}\mathrm{C} $$, 0 degrees C$$ {}<^>{{}<^>{\circ}}\mathrm{C} $$, and 23 degrees C$$ {}<^>{{}<^>{\circ}}\mathrm{C} $$, with notch depths of 7 and 10mm$$ \mathrm{mm} $$. The mean, upper, and lower limits of the fracture parameters are determined through normal distribution analysis, avoiding curve fitting. Structural fracture curves are constructed to evaluate the fracture behavior. Furthermore, the peak load predictions and theoretical minimum size meeting linear elastic fracture mechanics are quantified. The effects of discrete coefficients, discrete numbers, and average grain sizes are also analyzed to reflect the material's heterogeneity.SummaryImproved BEM enables precise prediction of fracture parameters from peak load directly.Size-independent fracture parameters are validated under varying notch depths and temperatures.Normal distribution avoids fitting errors, enhancing the reliability of fracture assessment.Quasi-brittle behavior clarified via discrete metrics reflecting asphalt heterogeneity

To enhance the early-stage crack resistance of warm-mixed recycled asphalt mixtures, various types of reinforcing fibers were incorporated and investigated through a multi-scale analysis. Digital Image Correlation (DIC) and Acoustic Emission (AE), both non-destructive techniques, were utilized to monitor damage evolution in realtime. This study investigates the effects of basalt fiber morphology and fracture loading modes on the fracture resistance and synergistic crack resistance mechanisms of fiber-reinforced warm-mixed recycled SBS modified asphalt mixtures (WRAM-BF). Edge-Notched Disc Bending (ENDB) tests were conducted under mode I, mode III, and mixed mode I/III loading conditions using flocculent and chopped basalt fibers, combined with DIC and AE monitoring techniques. AE signal parameters, including source localization, peak frequency, and ringing counts, were analyzed to characterize the initiation and evolution of internal microcracks. DIC strain field mapping and the damage factor were employed to quantify full-field mesoscale strain distributions and crack propagation. The results indicate that the integration of AE and DIC facilitates a thorough and quantitative assessment of fracture behavior in WRAM-BFs. Specifically, flocculent fibers were found to effectively delay microcrack initiation, whereas chopped fibers significantly suppressed macrocrack propagation under various fracture modes. The findings also offer insights into the toughening mechanisms of fiber-rejuvenator synergy in sustainable asphalt composites.

The anti-skid performance of asphalt pavement is the key index to judge the safety of pavement, and excellent anti-skid performance is also the most effective means to ensure the safety of vehicles. In many years of road operation and management, it is found that the loss of skid resistance of asphalt pavement is the most common disease in the road. Due to the decrease of road skid resistance, traffic safety and road service quality are seriously affected. In view of the factors affecting the skid resistance of asphalt pavement, the tire factors, materials, grading types, construction technology, operation and maintenance management are summarized. This paper analyzes the reasons for the attenuation of anti-skid performance of asphalt pavement by vehicle load, running time, water and pollutants, and the relevant test methods and evaluation models of anti-skid performance of asphalt pavement.

Warm-mix asphalt technology has been applied to recycled rubber asphalt binder (RAB), which forms warm-mixed crumb rubber-modified asphalt binder (W-RAB) as a "green" material for environmental conservation and to enhance road performance. Furthermore, low-temperature cracking is one of the major distresses for asphalt pavement, which drastically restricts ride quality and service level. Therefore, the main objective of this study is to comparatively analyze the low-temperature properties of W-RABs based on thermal stress and the simple fractional model. W-RABs were obtained by mixing 60 mesh recycled rubber (CR) and two different types of warm-mix additives, namely viscosity reducer (1, 2, and 3%) and surfactant (0.4, 0.6, and 0.8%). First, Hopkins and Hamming's numerical algorithm and the Boltzmann superposition principle were used for obtaining thermal stress σT. Subsequently, critical cracking temperature Tcr was derived using the single asymptote procedure (SAP) theory. Second, the simple fractional viscoelasticity model was used to calculate the creep compliance, damping ratio, and dissipation energy ratio, and the results were compared with the Superpave protocol results obtained with bending beam rheometer (BBR) tests. The results showed that a combination of CR and warm-mix additives could slightly improve the thermal crack resistance of the asphalt binder. The addition of 0.6% surfactant yielded the optimum performance, while only a high dosage (3%) of viscosity reducer provided a marked improvement in efficiency, which decreased with a decrease in temperature. This study recommends the use of RAB composited with 0.6% surfactant for areas with extremely low temperature.

In this study, comparative analysis was carried out to investigate the influence of crumb rubber (CR) powder size and warm mix additives (WMA) on the high-temperature properties of warm-mixed crumb rubber (CR-WMA) modified asphalts by temperature and frequency sweep test as well as repeated creep and recovery test. CR-WMA binders were obtained by mixing modifiers including two different types of rubber powder: an individual mesh and a mixed-mesh, and two different WMA additives: viscosity reducer and surfactant. Anti-rutting performance of asphalt binders was determined through several approaches employing various factors including phase angle delta, complex modulus G*, rutting factor G*/sin delta, modified rutting factor G*/(sin delta)(9), high failure temperature, equivalent viscosity eta', accumulated strain r(acc), ratio of permanent deformation to total deformation epsilon(p)/epsilon(L), and the Burgers model to determine creep compliance J and Generalized Voigt G(V). The results showed that the combination of CR and WMA exhibited a positive synergistic effect on asphalt's rheological properties; and CR-WMA modified binder containing mixed mesh CR powder and surfactant yielded optimum performance. Moreover, analysis of anti-rutting properties indicated that the effect of mixed powder size was found to be more prominent than that of single particle size, the effect of surfactant was better than that of viscosity reducer, and the modification effect of composite modifiers was greater than that of single modifier alone. Furthermore, the permanent deformation occurred continuously with the increase in the number of loadings and the delayed elastic performance was unstable at the beginning of loading progress. (C) 2021 Elsevier Ltd. All rights reserved.

为实现从胶粉改性沥青混合料的动态模量测试结果预测对应的相位角,并从线性粘弹性角度评估不同胶粉改性沥青混合料的高低温性能.通过复数模量试验结果,构建近似满足Kramers-Kronig(K-K)关系由动态模量和相位角主曲线,按照粘弹性原理进一步得到时域下的松弛模量和蠕变柔量主曲线.结果表明,相位角的模型预估值不及动态模量但依然显示出较高的精确性.Cole-Cole图和Black Space图都证明了实测结果及模型的预测结果均符合线性粘弹性理论.松弛模量和蠕变柔量的变化规律又表明,HMA-60的高温抗车辙能力不及HMA-C,但低温抗裂性能优于HMA-C.温拌后混合料的高温抗车辙能力及低温抗裂性能都得到改善.WMA-60的高温抗车辙能力不及WMA-C,但低温抗裂性能优于WMA-C.

To identify the most accurate approach for constructing of the dynamic modulus master curves for warm mix crumb rubber modified asphalt mixtures and assess the feasibility of predicting the phase angle master curves from the dynamic modulus ones. The SM (Sigmoidal model) and GSM (generalized sigmoidal model) were utilized to construct the dynamic modulus master curve, respectively. Subsequently, the master curve of phase angle could be predicted from the master curve of dynamic modulus in term of the K-K (Kramers–Kronig) relations. The results show that both SM and GSM can predict the dynamic modulus very well, except that the GSM shows a slightly higher correlation coefficient than SM. Therefore, it is recommended to construct the dynamic modulus master curve using GSM and obtain the corresponding phase angle master curve in term of the K-K relations. The Black space diagram and Wicket diagram were utilized to verify the predictions were consistent with the LVE (linear viscoelastic) theory. Then the master curve of storage modulus and loss modulus were also obtained. Finally, the creep compliance and relaxation modulus can be used to represent the creep and relaxation properties of warm-mix crumb rubber-modified asphalt mixtures.

To study the linear viscoelastic (LVE) of crumb rubber-modified asphalt mixtures before and after the warm mix additive was added methods of obtaining the discrete and continuous spectrum are presented. Besides, the relaxation modulus and creep compliance are constructed from the discrete and continuous spectrum, respectively. The discrete spectrum of asphalt mixtures can be obtained from dynamic modulus test results according to the generalized Maxwell model (GMM) and the generalized Kelvin model (GKM). Similarly, the continuous spectrum of asphalt mixtures can be obtained from the dynamic modulus test data via the inverse integral transformation. In this paper, the test procedure for all specimens was ensured to be completed in the LVE range. The results show that the discrete spectrum and the continuous spectrum have similar shapes, but the magnitude and position of the spectrum peaks is different. The continuous spectrum can be considered as the limiting case of the discrete spectrum. The relaxation modulus and creep compliance constructed by the discrete and continuous spectrum are almost indistinguishable in the reduced time range of 10(-5)s-10(3)s. However, there are more significant errors outside the time range, and the maximum error is up to 55%.

为防止失控车辆驶出路外,保护车辆及乘客免受重大损失,并能起到引导驾驶员视线和美化路容的作用,中央护栏可采用钢筋混凝土护栏。以张石高速公路石家庄段中央混凝土护栏施工为例,重点介绍混凝土护栏的施工工艺和方法。

In order to achieve a high-yield of sweet sorghum through optimizing the cultivation measures, the relationships between straw yield, grain yield, the average straw Brix, seed manure and density of that in Lin xi area, Inner Mongolia were studied by the L9(34) orthogonal experiment. The results showed: the production of sweet sorghum stalks, grain yield and average straw Brix were mainly affected by density. The cultivation measures in Lin xi area in Inner Mongolia were optimized as follow: urea 8.8 kg/667m2, diamidogen 6.2 kg/667m2, potassium sulfate 10.6 kg/667m2 and 6000 plants/hm2 of density.

The endangered plant of Tetraena mongolica and Songaricum schrenk were relict flora and distribute only in China.They are valuable resources for scientific research on species evolution,plant anti-stress and biomaterials.In this paper,the main fatty acids content in the stem and leaves of Tetraena mongolica and Songaricum schrenk were detected.The results showed that the variation trends of saturated fatty acid in Tetraena mongolica and Songaricum schrenk takes a parabola shape,while that of unsaturated fatty acid goes down with the process of growth.From spring to autumn,unsaturated fatty acids play an important role on development and stress-resisting by forming a store-release cycle.The content of unsaturated fatty acid are higher in both stems and leaves of Tetraena mongolica and Songaricum schrenk,especially that of linoleic acid and linolenic acid,when the plants just turn green in spring.That means the nutritive organs above ground of Tetraena mongolica and Songaricum schrenk could be used as materials for oil extraction,nutrition and health care.Tetraena mongolica and Songaricum schrenk are extemely drought-resistant species.How to protect and use this valuable resource would have great effect on environment and species protection in local area of Inner Mongolia.

An improved Trizol method has been developed for total RNA extraction from the leaves of the Caragana microphylia Lam which contains high leave of proteins and polysaccharides.

Objective: To develop a new technology of extracting galanthamine.Methods: Galanthamine was extracted from the bulb of Lycoris aurea by heat reflux.An orthogonal experiment was conducted to analyze the influences of different factors and their levels on the extracting rate of galanthamine.One-step extraction by basification was adopted and HPLC was made for separation and preparation.Results: The optimal extract conditions were as follows: solid and liquid ratio was 1∶10,ethanol 95%,temperature 85 ℃,extract 2 times for 2 h for each,under which the extraction rate of galanthamine was up to 81.12%.The yield of alkalization extraction and HPLC preparation was 77% and 50.8%,respectively.The purity of galanthamine was up to 92.5%.Conclusion: The process of alkalization extraction is simple and HPLC preparation can separate galanthamine,which is flexible to operate.