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Background: Massive hemorrhage is the main cause of preventable death after trauma. This study aimed to establish prediction models for early diagnosis of massive hemorrhage in trauma.Methods: Using the trauma database of Chinese PLA General Hospital, two logistic regression (LR) models were fit to predict the risk of massive hemorrhage in trauma. Sixty-two potential predictive variables, including clinical symptoms, vital signs, laboratory tests, and imaging results, were included in this study. Variable selection was done using the least absolute shrinkage and selection operator (LASSO) method. The first model was constructed based on LASSO feature selection results. The second model was constructed based on the first vital sign recordings of trauma patients after admission. Finally, a web calculator was developed for clinical use.Results: A total of 2353 patients were included in this study. There were 377 (16.02%) patients with massive hemorrhage. The selected predictive variables were heart rate (OR: 1.01; 95% CI: 1.01-1.02; P<0.001), pulse pressure (OR: 0.99; 95% CI: 0.98-0.99; P = 0.004), base excess (OR: 0.90; 95% CI: 0.87-0.93; P<0.001), hemoglobin (OR: 0.95; 95% CI: 0.95-0.96; P<0.001), displaced pelvic fracture (OR: 2.13; 95% CI: 1.48-3.06; P<0.001), and a positive computed tomography scan or positive focused assessment with sonography for trauma (OR: 1.62; 95% CI: 1.21-2.18; P = 0.001). Model 1, which was developed based on LASSO feature selection results and LR, displayed excellent discrimination (AUC: 0.894; 95% CI: 0.875-0.912), good calibration (P = 0.405), and clinical utility. In addition, the predictive power of model 1 was better than that of model 2 (AUC: 0.718; 95% CI: 0.679-0.757). Model 1 was deployed as a public web tool ( http://82.156.217.249:8080/ ).Conclusions: Our study developed and validated prediction models to assist medical staff in the early diagnosis of massive hemorrhage in trauma. An open web calculator was developed to facilitate the practical application of the research results. [ABSTRACT FROM AUTHOR]

Cement-casting asphalt mixture (CCAM) exhibits excellent antirutting properties and has been widely used to address the severe rutting distress across the world. However, CCAM's failure mechanism has not been comprehensively understood. To this end, the contribution rates of porous asphalt mixture (PAM), cementitious network, and asphalt-cement interface phases to CCAM's pavement performance are evaluated. A novel method was developed to fabricate the cementitious network with the aid of plastic balls. Abrasion loss, strength, peak force, and fracture energy of PAM, cement samples, and CCAM samples are obtained through different tests. Analysis results show that the contribution rate of cementitious network to Cantabro loss is around 60% and that of the interface phase is around 30%. Interface phase and PAM phase approximately contribute 90% to the overall strength and fracture energy of CCAM. With the increase of polymer contents in asphalt binder, the contribution rate of PAM phase increases and the contribution rate of interface decreases. Contribution rates results together with samples' fracture surface observation verify that the interaction between asphalt skeleton and cement network plays a vital role during CCAM's failure process. Attention should be given to the physical-chemical interactions between asphalt and cement in the future study. [ABSTRACT FROM AUTHOR]

Sacubitril/valsartan, simultaneously inhibits neprilysin and angiotensin II receptor, showed an effect in reducing blood pressure (BP). The authors aimed to study whether it can be used as an antihypertensive agent in patients with refractory hypertension who have already been treated. A total of 66 Chinese patients with refractory hypertension were enrolled. Patients received sacubitril/valsartan 200 instead of angiotensin II receptor blocker or angiotensin converting enzyme inhibitor while other agents continued. If BP was uncontrolled after 4 weeks, sacubitril/valsartan was increased to 400 mg. The BP reduction was evaluated by office BP and ambulatory BP monitoring after 8‐week treatment. The baseline office BP and mean arterial pressure (MAP) were 150.0/95.0 mmHg and 113.3 mmHg. BP and MAP reduced to 130.6/83.2 mmHg and 99.0 mmHg at week 8. Office BP and MAP reductions were 19.4/11.8 mmHg and 14.3 mmHg at endpoint (all p <.001). The 24‐h, daytime and nighttime ambulatory BP were 146.2/89.1, 148.1/90.3, and 137.5/83.7 mmHg, respectively at baseline, and BP reduced to 129.6/79.8, 130.6/81.1, and 121.7/75.8 mmHg, respectively at week 8. The 24‐h, daytime and nighttime ambulatory BP reductions were 16.6/9.3, 17.5/9.2, and 15.8/7.9 mmHg, respectively at endpoint (all p <.001). Sacubitril/valsartan significantly reduced office and ambulatory BP in refractory hypertension patients. Our study provided new evidence for sacubitril/valsartan in refractory hypertension. [ABSTRACT FROM AUTHOR]

Sepsis is a life-threatening systemic syndrome characterized by various biological, biochemical, and physiological abnormalities. Due to its high mortality, identifying sepsis patients with high risk of in-hospital death early and accurately will help doctors make optimal clinical decisions and reduce the mortality of sepsis patients. In this paper, we propose a length insensitive TCN-based model to predict sepsis patient's death risk in the future k hours, which is the first work for sepsis death risk early warning model only based on vital signs time series to our best knowledge. Furthermore, we design residual connections between temporal residual blocks to improve the prediction performance and stability especially on short input sequences. We validate and evaluate our model on two freely-available datasets, i.e., MIMIC-IV and eICU, from which 16,520 and 29,620 patients are selected respectively. The experiment results show that our model outperforms LSTM and other machine learning methods, as it has the highest sensitivity and Youden index in almost all cases. Meanwhile, the Youden index of the TCN-based model only slightly decreases by 0.0233 and 0.0307 when the time range of the input sequence changes from 24 to 4 h for k equal to 6 and 12, respectively. [ABSTRACT FROM AUTHOR]

Accurate cannulation of the adrenal vein is challenging during adrenal venous sampling (AVS) because of the variations in adrenal vein anatomy. This study aimed to investigate the adrenal venous morphology in Chinese and improve the success rate of AVS. A total of 221 participants with primary aldosteronism (PA) who underwent AVS were enrolled. Compare the morphology among subgroups divided according to sex, body mass index (BMI), and with or without adenoma. The success rate of right, left, and bilateral AVS was 98.60%, 97.20%, and 96.85%, respectively. The triangular pattern was the most common (39.37%) on the right side, while the glandlike pattern (70.14%) on the left. The proportion of adrenal venous morphology varies among patients with different sexecs (χ2 = 21.335, P < .001), BMI (χ2 = 10.642 P = .031), and with or without adenoma (χ2 = 10.637, P = .031) on the right side, and the male, obese and adenoma group showed a higher proportion of glandlike pattern than triangular pattern. If only dependent on computed tomography, 9.05% of patients incorrectly diagnose the dominant side, 14.48% of patients would have inappropriate surgery meanwhile 25.34% of patients would miss the surgical opportunity. In conclusion, the most common types of right and left adrenal venous morphology were triangular pattern and glandlike pattern, respectively. Sex, BMI, and the presence of adenoma affected right adrenal venous morphology. Adequate knowledge of the adrenal venous morphology is critical for improving the success rate of AVS and making an appropriate treatment for PA. [ABSTRACT FROM AUTHOR]

• Eight gradations with different coarse aggregate contents were investigated. • The relationships between basic gradation performance and mechanical performance were established. • The creep of different gradations mortars was tested at high temperature. • The Burgers model accurately reflected the creep parameters of the SFP specimens. Semi-flexible pavement (SFP) has been widely used for ant-rutting performance and resistance in heavy load conditions. The asphalt mixture skeleton was the central part in the complex-skeleton material system. However, few studies have been made on the connection of asphalt mixture skeleton composition and performance on semi-flexible pavement material. Therefore, the relationship between the skeleton gradation volumetric characteristic and mechanical properties of semi-flexible pavement material was investigated. Eight gradations with different coarse aggregate contents were constituted. The mechanical performances were conducted to establish the relationship between primary gradation performance. The result shows that the porosity of the asphalt matrix and Cantabro abrasion test are related to the composition of gradation. The tensile performance, shear characteristics, and compressive strength were affected by the voids filled asphalt (VFA), porosity, and fine aggregate to asphalt ratio (FB), respectively. The Burgers model accurately reflected the creep curves of the semi-flexible pavement material specimens. The creep modulus was related to the VFA, porosity, and effective asphalt content (P be). The gradation design parameters of open-gradation asphalt mixtures for semi-flexible pavement materials could be obtained based on the target performance. It is possible to reduce material testing times based on the correlation analysis effectively. [ABSTRACT FROM AUTHOR]

• The anti-cracking abilities of semi-flexible pavement (SFP) are evaluated. • SCB tests are employed to characterize the cracking resistance of SFP mixtures. • Laboratory results (Flexibility index) correlate well with field cracking performance. • MA modifier and fiber would enhance the anti-cracking resistance of SFP mixtures. Semi flexible pavement (SFP) has drawn great attention in recent years due to its high load bearing capacity. Its strength, rutting resistance, and component constitution have been investigated comprehensively in studies. However, understanding on its cracking performance and mechanism is limited. To this end, this paper evaluates the cracking performance of SFP mixture by utilizing the semi-circular bending (SCB) test. Both SCB monotonic and fatigue tests are employed to characterize the cracking resistance of SFP mixtures with three kinds of asphalt binders, which include SBS (Styrene-Butadiene-Styrene) modified asphalt binder, MA (Modified Agent-100, developed by Sobute New Materials Co. Ltd) modified asphalt binder, and fiber incorporated MA modified asphalt binder. A field inspection was conducted to verify the connections between laboratory results and field performance. SCB results show that the addition of MA-100 and fiber (corresponding to higher optimal asphalt content) lowers the strength of SFP mixtures but increases the fracture energy and flexiblity index at intermediate temperatures. The fatigue test result demonstrates that SFP mixture with MA modified asphalt binder and fibers exhibits the best fatigue performance in the high stress ratio area. According to the field inspection results, pavements using MA modified asphalt binder and fibers have fewer cracks. It is found that there is a good relationship between SCB results obtained at 25 °C (fracture energy and flexibility index) and field crack counts. [ABSTRACT FROM AUTHOR]

Plenty work has been done on asphalt’s moisture susceptibility at macro scales. However, limited work was done at micro scale to aid in the understanding of interactions between asphalt and moisture. This paper uses atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) to investigate the mechanism of asphalt property changes during water immersion. Six asphalt samples from same crude oils sources are prepared. Wet-conditioned samples were fabricated by immersing dry samples in water for 72 h. Samples’ micro mechanical properties were obtained by AFM mechanical tests. Chemical alterations were detected by FTIR test. Results from AFM and FTIR tests are compared and analyzed. It is found that formation of asphalt microstructure is closely related to long chain index. Both microstructure and long chain index are less susceptible to water immersion when compared to matrix and other functional group indexes. AFM mechanical results show reasonable connections to FTIR results which indicates that polar components tend to interact with polar water molecules. [ABSTRACT FROM AUTHOR]

Context: Graphene oxide(GO) has been widely used in asphalt modification due to its excellent properties. To reveal the interaction effect between GO and asphalt materials, the microscopic behavior and molecular structure changes of asphalt and GO/asphalt were investigated by molecular dynamics (MD) simulations. Mean square displacement (MSD) results showed that GO significantly inhibited the diffusion of molecules of asphalt components. Radial distribution function (RDF) results that GO destroys the original sol-type structure of asphalt. Simultaneously, GO adsorbed resins at low-temperature, adsorbed asphaltenes at high-temperature, and dispersed as a dispersed phase in the light components. The concentration of the dispersed phase in the asphalt colloidal structure was increased and the mutual attraction was enhanced. This improves the deformation resistance at high temperature, but weakens the ductility at low temperatures. Methods: To investigate the mechanism of action of GO-modified asphalt, the asphalt model and the GO/asphalt composite system model were constructed using the Amorphous Cell module in Materials Studio 2020 software. Subsequently, molecular dynamics simulations of the GO/asphalt composite system were performed using the Forcite module, while the interactions between atoms and molecules were described using the COMPASS II force field. [ABSTRACT FROM AUTHOR]

Bio-binder is a renewable material which can be derived from natural resources. Applications of bio-binder in enhancing asphalt’s properties have gained profound progresses in past several years. However, limitation still exists in our knowledge on adhesion property of asphalt blended with bio-binder. This study aims to characterize adhesion behavior of bio-binder modified asphalt using sessile drop device (SDD) and atomic force microscopy (AFM). Relationship between the two test results is also investigated. It is shown that addition of bio-binder would introduce different impacts on surface properties for different base asphalts (Pen30 and Pen70 asphalts in this paper), which may be attributed to distinct compatibilities between bio-binder and different asphalts. And the work of adhesion data demonstrates that the bio-binder enhances the interaction between basalt and bio-binder modified Pen70 asphalt binders while depress the interaction between basalt and bio-binder modified Pen30 asphalt binders. It is also found that AFM adhesive force is tip-dependent which may be interpreted using different contact mechanics. In this paper, the high coefficient of variation in soft tip’s data may result from the capillary force and contamination during scanning. Interestingly, dispersive surface free energy and AFM results show some reasonable agreements for modified Pen70 asphalts, though there is still a gap between these two methods’ results. It is speculated that the variations between surface free energy method and AFM measurement can be attributed to the differences in probe substance, test scale and measured components. Findings in this paper not only promote the development of bio-binder modified asphalt, but also shed lights of the application of AFM in characterization of asphalt’s adhesion property. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-stage pre-treatment method for food waste (FW) adapted to incineration was proposed, and resources were recovered along with energy. • The freshwater in FW was recovered by a freeze-drying process and its availability was detected and proven. • The negative effect of the presence of lipids on the fuel properties evolution of torrefaction products was investigated. • The fuel properties and combustion performance of coal-like torrefaction products from FW were well evaluated. As of 2020, the annual generation of municipal solid waste (MSW) in China has surged to 235.12 Mt, and food waste (FW) accounts for more than 60 %. The most common treatment method is incineration, which accounts for 62.13 %. This research proposes a three-stage pretreatment method for FW that is suitable for incineration while recovering by-products and energy from the pretreatment process. The first stage is dehydration; as compared to hot air drying (HAD) processes, freeze drying (FD) exhibits a higher dehydration and oil preservation rate, allowing for the preservation of organic matter content and the recovery of freshwater resources from FW. The second stage is oil recovery; the FW extracted oil (FWEO) can be used to produce biodiesel, and this stage also helps to improve the effectiveness of the subsequent torrefaction process. The third stage improves the energy and fuel characteristics of the organic residue of FW and enhances the combustion performance by optimizing the torrefaction temperature. The solid fuel obtained at a torrefaction temperature of 350 °C shows the best combustion performance, with a solid yield of 35.76 %, a torrefaction temperature of 300 °C might be chosen to further improve the solid yield. [ABSTRACT FROM AUTHOR]

Abstracts Use of bio-binder could address depletion of petroleum oil, pollution from residue waste, greenhouse gases emissions, and development of sustainable asphalt pavement that is both economically and environmentally friendly. This study investigated the physical and chemical properties of bio-oil rejuvenated asphalt with a series of test. A pre-treatment procedure was introduced to upgrade the biodiesel residue produced from waste cooking oil. Aged asphalt was prepared with a laboratory short-term aging method. The optimal content of the bio-oil was determined by conventional tests and related index, such as penetration, softening point, and ductility, to rejuvenate aged asphalt to its virgin level. Rheological properties, including viscosity, high-temperature rutting resistance, and low-temperature cracking resistance, of virgin, aged, and bio-oil rejuvenated asphalts were then investigated. Afterward, asphalt fraction components, functional groups, and microstructures of virgin, aged and bio-oil rejuvenated asphalts, together with the molecular information of bio-oil, were analyzed with the aid of micro testing techniques. Finally, the moisture susceptibilities were evaluated by conducting micro mechanical experiments. Results clearly demonstrate that bio-oil could soften aged asphalt and improve its low-temperature cracking resistance. Workability was improved due to the reduction of viscosity. Moreover, bio-oil was found to be a complex organic mixture with low molecular weight. Bio-oil was able to compensate aged asphalt for the loss of light components and may also interact with polymer in modified asphalt. Meanwhile, the aggregation of polar components after aging can be mitigated. Thus, the properties of aged asphalt would be enhanced with the addition of bio-oil rejuvenator. However, the anti-moisture performance of bio-oil rejuvenated base (Pen50) asphalt needs to be further improved due to the presence of hydrophilic functional groups and components. In sum, this paper presents the superiorities and potential application challenges of using biodiesel-residue-based bio-oil to rejuvenate aged asphalt. [ABSTRACT FROM AUTHOR]

• The impacts of gradation types and compaction levels of PAM on the pavement performance of SFP is analyzed. • The volumetric properties of PAM with different gradations change in linear trends as different compaction levels are used. • Proper compaction level and higher VFA could together make SFP more cracking-resistant. • SFP samples fabricated with the VCV of PAM lower than 19% exhibit excellent all-around pavement performances. Semi-flexible pavement (SFP) has been widely used to address rutting distress across China in recent years. The field application shows that SFP has excellent anti-rutting performance but relatively poor anti-cracking ability when compared with flexible asphalt pavement. Formation of cementitious network is closely related to the connected voids within porous asphalt mixture (PAM). Different gradations and compaction levels would contribute to different volumetric contents and distribution of connected voids in asphalt skeleton. Thus, the pavement performance of SFP could be theoretically regulated by using different combination of gradations and compaction levels for PAM fabrication. However, the relationship between aforementioned two factors with pavement performance of SFP is not well established. Therefore , volumetric properties of PAM samples fabricated with three different gradations and three compaction levels are characterized firstly in present paper. The pavement performances of grouted samples are evaluated then. Afterwards, the relationship between volumetric parameters of PAM and pavement performance of SFP are analyzed. In the end, the reusable two-factor analysis of variance is carried out to check the significance of different factors. Results show that the 25℃ IDT strength of SFP ranges from 0.7 to 1.0 MPa while that of PAM is from 0.3 to 0.6 MPa by using different gradation types and compaction levels. TSR of all the SFP samples exceed 80%, which indicating that SFP has excellent anti-freeze–thaw ability. The Cantabro loss of SFP can be approximately decreased from 13% to 9% by using finer gradation. Different SFP samples have similar flexural strengths but significantly different maximum flexural strain and modulus. It is found that gradation type has the more significantly impacts on the pavement performance of SFP than compaction level. Based on the results in present paper, SFP samples fabricated with the VCV of PAM lower than 19% exhibit excellent all-around pavement performances. The findings can provide a guidance for the design and application of SFP in the field. [ABSTRACT FROM AUTHOR]

Objectives. Early warning prediction of massive hemorrhages can greatly reduce mortality in trauma patients. This study aimed to develop and validate dynamic prediction models for massive hemorrhage in trauma patients. Methods. Based on vital signs (e.g., heart rate, respiratory rate, pulse pressure, and peripheral oxygen saturation) time-series data and the gated recurrent unit algorithm, we characterized a group of models to flexibly and dynamically predict the occurrence of massive hemorrhages in the subsequent T hours (where T = 1, 2, and 3). Models were evaluated in terms of accuracy, sensitivity, specificity, positive predictive value, negative predictive value, F1 score, and the area under the curve (AUC). Results. Results show that of the 2205 trauma patients selected for model development, a total of 265 (12.02%) had a massive hemorrhage. The AUCs of the model in the 1-h-group, 2-h-group, and 3-h-group were 0.763 (95% CI: 0.708–0.820), 0.775 (95% CI: 0.728–0.823), and 0.756 (95% CI: 0.715–0.797), respectively. Finally, the models were used in a web calculator and information system for the hospital emergency department. Conclusions. This study developed and validated a group of dynamic prediction models based on vital sign time-series data and a deep-learning algorithm to assist medical staff in the early diagnosis and dynamic prediction of a future massive hemorrhage in trauma. [ABSTRACT FROM AUTHOR]

• Three-dimensional cementitious network is fabricated in a novel way. • Pore structures would lower cement grouting material's strengths. • The cementitious network on CCAM's fracture behavior is studied. • The C/F ratio of grouting material correlates well with one type of CCAM. Taking good advantage of both rigid cement and flexible asphalt mixture, cement casting asphalt mixture is developed to address the traditional distress in asphalt pavement. However, the relatively poor cracking resistance of CCAM limits its application in practice. Since the cracking mechanism of CCAM is still unknown, modification on the mixture design of CCAM cannot be done. In this regard, this paper focuses on investigating the influences of an artificial three-dimensional cementitious network on the fracture property of CCAM. In order to simulate the cementitious network, the pore structure in the prism sample is formed by using plastic foam balls of different sizes. The mechanical properties of beam samples at different curing days are measured. The semi circular bending test is used to characterize the strength and fracture properties of CCAM with different grouting materials. It is shown that the pore structure lowers the strength of the prism beams. Pore structures would induce more loss to the compressive strength of the beam samples than to its flexural strength. The cracking resistance of CCAM is determined by the asphalt mixture skeleton and cement network by analyzing the fracture energy and FI data. It is found that the compressive/flexural (C/F) ratio of the prism beam with 1 cm diameter plastic foam balls correlates well with the FI result of the CCAM. The results show that a moderate C/F ratio would make CCAM have fracture energy and flexibility, which makes it difficult for cracks to readily initialize and develop. The findings in this paper would provide guidance for the further selection of cementitious materials for the fabrication of CCAM with an excellent pavement performance. [ABSTRACT FROM AUTHOR]

Aims. To evaluate the impact of neutrophil-to-lymphocyte ratio (NLR) on periprocedural pulmonary hypertension (PH) and 3-month all-cause mortality in patients with aortic stenosis (AS) who underwent transcatheter aortic valve replacement (TAVR) and to develop a nomogram for predicting the mortality for these patients. Methods and Results. 124 patients undergoing TAVR were categorized into three groups according to systolic pulmonary artery pressure (sPAP): Group I (no PH, n = 61) consisted of patients with no pre- and post-TAVR PH; Group II (improved PH, n = 35) consisted of patients with post-TAVR systolic pulmonary artery pressure (sPAP) decreased by more than 10 mmHg compared to pre-TAVR levels; and Group III (persistent PH, n = 28) consisted of patients with post-TAVR sPAP no decrease or less than 10 mmHg, or new-onset PH after the TAVR procedure. The risk of all-cause mortality within 3 months tended to be higher in Group II (11.4%) and Group III (14.3%) compared to Group I (3.3%) (P = 0.057). The multinomial logistic regression analysis demonstrated a positive correlation between NLR and both improved PH (OR: 1.182, 95% CI: 1.036–1.350, P = 0.013) and persistent PH (OR: 1.181, 95% CI: 1.032–1.352, P = 0.016). Kaplan–Meier analysis revealed a significant association between higher NLR and increased 3-month all-cause mortality (16.1% vs. 3.1% in lower NLR group, P = 0.021). The multivariable Cox regression analysis confirmed that NLR was an independent predictor for all-cause mortality within 3 months, even after adjusting for clinical confounders. A nomogram incorporating five factors (BNP, heart rate, serum total bilirubin, NLR, and comorbidity with coronary heart disease) was developed. ROC analysis was performed to discriminate the ability of the nomogram, and the AUC was 0.926 (95% CI: 0.850–1.000, P < 0.001). Conclusions. Patients with higher baseline NLR were found to be at an increased risk of periprocedural PH and all-cause mortality within 3 months after TAVR. [ABSTRACT FROM AUTHOR]

To evaluate the association of uric acid (UA) with adverse outcomes and its potential mediator in patients with left ventricular diastolic dysfunction (LVDD) and pulmonary hypertension (PH). We retrospectively analyzed 234 patients with LVDD and PH. The baseline characteristics of patients with low UA (≤ 330 µmol/L) group were compared with high UA (> 330 µmol/L) group. Adverse outcomes included all-cause mortality, cardiac death and heart failure (HF) hospitalization. Their association with UA and the mediator were evaluated using Cox regression and mediation analysis. The mediation proportion was further quantified by the R mediation package. During a mean follow-up of 50 ± 18 months, there were 27 all-cause deaths, 18 cardiovascular deaths and 41 incidents of HF hospitalization. Multivariable Cox regression analysis showed UA was an independent risk factor of adverse outcomes in LVDD and PH patients, even after adjusting for age, sex, body mass index, medical histories, systolic blood pressure, fasting blood glucose, total cholesterol, triglyceride, eGFR, BNP and medications. The hazard ratios (HRs) for UA (per 10 µmol/L increase) were as below: for all-cause mortality, HR 1.143, 95% CI 1.069–1.221, P < 0.001; for cardiac death, HR 1.168, 95% CI 1.064–1.282, P = 0.001; for HF hospitalization, HR 1.093, 95% CI 1.035–1.155, P = 0.001. Neutrophil-to-lymphocyte ratio (NLR) played a partial mediation role in the association, and the mediation proportion for NLR on the UA-adverse outcomes were 21%, 19% and 17%, respectively. In patients of LVDD with PH, higher UA level was independently correlated with adverse outcomes. Furthermore, NLR partially mediated the effect of UA on the risk of all-cause mortality, cardiac death and HF hospitalization. [ABSTRACT FROM AUTHOR]

Semiflexible pavement (SFP) is constructed by pouring grouting material into porous asphalt (PA) mixture. SFP has been widely used to address the rutting distress issues across China in recent years. However, studies on its cracking resistance are limited and the failure mechanism of the SFP mixture has not been fully explored nor understood in a comprehensive way. Moreover, the influences of the curing time on the cracking property of the SFP mixture are still not clear. To this end, the strength development and shrinkage properties of grouting materials are determined by utilizing the three-point beam bending test and the shrinkage test. The semicircular bending (SCB) test and the scanning electron microscope-energy-dispersive spectrum (SEM-EDS) are conducted in this study to investigate the cracking resistance and failure mechanism of SFP mixtures with different curing days. Results show that both the strength and shrinkage of grouting materials would develop as the curing time was extended from 0 days to 14 days. SCB test results show that SFP mixtures have higher tensile strength but a lower flexibility index (FI) than PA mixture. It is found that the cracking resistance of SFP mixture is influenced by both the grouting materials' strength and shrinkage. SEM-EDS analysis demonstrates that the cement-asphalt interface is a stress concentration site and therefore is the weak zone where cracks would initially develop. The microcracks found in the interface zone with different curing days may contribute to the decline of the SFP mixture's anticracking ability. This study sheds light on the further application of SFP in practical projects. [ABSTRACT FROM AUTHOR]

The poor cracking resistance of Semi-Flexible Pavement (SFP) mixture has limited its wider application. Particularly, the dual skeletal interlocking structure makes its damage process complicated. Its fracture process is expected to change with aggregate gradation and temperature, but the relevant knowledge is very limited. Thus, this study aims to investigate the effects of the two factors on the fracture characteristics of SFP using the acoustic emission (AE) technique and X-ray computed tomography (CT) approach. SFP specimens with three gradations (the target cement grout volume is 22%, 25% and 30%, respectively) were fabricated and subjected to the split tensile tests at three different temperatures (−10°C, 10°C and 25°C). Machine learning-based techniques were applied to analyze the AE signals to improve the understanding of the mesoscale damage process. Although the analysis of macro mechanical parameters showed the diminishing effect of temperature dependency on the fracture process with an increase in cement grout volume, the effect was found to be still significant based on the mesoscale analysis. Besides, it was found that the damage process transferred from the main crack going through cement to distributed meso-cracks in asphalt and cement with the temperature increase. [ABSTRACT FROM AUTHOR]

The poor cracking resistance of Semi-Flexible Pavement (SFP) mixture has limited its wider application. Particularly, the dual skeletal interlocking structure makes its damage process complicated. Its fracture process is expected to change with aggregate gradation and temperature, but the relevant knowledge is very limited. Thus, this study aims to investigate the effects of the two factors on the fracture characteristics of SFP using the acoustic emission (AE) technique and X-ray computed tomography (CT) approach. SFP specimens with three gradations (the target cement grout volume is 22%, 25% and 30%, respectively) were fabricated and subjected to the split tensile tests at three different temperatures (−10°C, 10°C and 25°C). Machine learning-based techniques were applied to analyze the AE signals to improve the understanding of the mesoscale damage process. Although the analysis of macro mechanical parameters showed the diminishing effect of temperature dependency on the fracture process with an increase in cement grout volume, the effect was found to be still significant based on the mesoscale analysis. Besides, it was found that the damage process transferred from the main crack going through cement to distributed meso-cracks in asphalt and cement with the temperature increase. [ABSTRACT FROM AUTHOR]

Strength is a crucial performance indicator for evaluating the durability of pervious concrete (PC). However, there are few models for estimating the remaining strength of in-service PC in sulfate and dry-wet cycle circumstances. Even though there are already direct detection methods for strength, nondestructive testing methods are still worth additional research. This paper aims to give a calculation model for the residual strength of PC under corrosion conditions based on ultrasonic methods, which is economical and convenient for engineering applications. The apparent morphological, compressive strength, and ultrasonic velocity of PC against sulfate and dry-wet cycle attack were examined. The results highlight that the primary cause of the macroscopic mechanical deterioration is the worsening in interface strength. Furthermore, the compressive strength and ultrasonic wave velocity of PC followed the same trends during sulfate and dry-wet cycles, increasing first and subsequently decreasing. Additionally, using the curve-fitting approach, an empirical model of strength deterioration based on ultrasonic velocity was developed and validated utilizing experimental data, demonstrating that the proposed model could more accurately define the strength progression. The results can provide an effective calculation method for monitoring the residual strength of PC pavement engineering in a corrosive environment. [ABSTRACT FROM AUTHOR]

Moisture damage seriously deteriorates asphalt pavement’s performance and durability and is therefore one of the major problems of asphalt pavements. Currently, researchers pay most attention to macro investigation of moisture damage in asphalt materials. However, moisture damage in asphalt materials can be attributed to the complex interactions between water, asphalt and aggregates occurring at the micro level so that macro tests cannot provide precise insight into this process and its mechanisms. To this end, two promising micromechanical tests, atomic force microscopy (AFM) and nanoindentation, were used in this paper to capture the micromechanical properties of asphalt binder and mixture samples before and after moisture damage. For data comparison, surface energy method and freeze-thaw splitting test were also used. Results show that AFM and nanoindentation are promising methods in investigation of asphalt materials’ moisture damage because they can quantitatively determine the loss of asphalt samples’ strength and also determine their damage types (adhesion or cohesion failure). Results of surface energy method and freeze-thaw splitting test correlate well with AFM and nanoindentation results in characterization of moisture susceptibility of asphalt binder and mixture samples respectively. It is concluded that these four testing methods can achieve a systematic and accurate evaluation of asphalt materials’ moisture resistance. [ABSTRACT FROM AUTHOR]

Moisture damage seriously deteriorates asphalt pavement’s performance and durability and is therefore one of the major problems of asphalt pavements. Currently, researchers pay most attention to macro investigation of moisture damage in asphalt materials. However, moisture damage in asphalt materials can be attributed to the complex interactions between water, asphalt and aggregates occurring at the micro level so that macro tests cannot provide precise insight into this process and its mechanisms. To this end, two promising micromechanical tests, atomic force microscopy (AFM) and nanoindentation, were used in this paper to capture the micromechanical properties of asphalt binder and mixture samples before and after moisture damage. For data comparison, surface energy method and freeze-thaw splitting test were also used. Results show that AFM and nanoindentation are promising methods in investigation of asphalt materials’ moisture damage because they can quantitatively determine the loss of asphalt samples’ strength and also determine their damage types (adhesion or cohesion failure). Results of surface energy method and freeze-thaw splitting test correlate well with AFM and nanoindentation results in characterization of moisture susceptibility of asphalt binder and mixture samples respectively. It is concluded that these four testing methods can achieve a systematic and accurate evaluation of asphalt materials’ moisture resistance. [ABSTRACT FROM AUTHOR]

In this study, a bio-binder/plasticizer-based rejuvenator was used to restore the properties of a long-term-aged asphalt binder. The chemical properties of the rejuvenated-asphalt binder were then analyzed. Pen70 asphalt and an SBS-modified asphalt were used in this study as virgin asphalt binders. A pressure-aging-vessel test was conducted to simulate the long-term aging process of the asphalt samples. The aged asphalt binders were blended with a bio-rejuvenator at dosages of 5% and 10%. The results show that adding the bio-rejuvenator with a dosage of 10% helps in restoring the workability and rutting resistance of the long-term-aged asphalt to their original level. The fatigue resistance and low-temperature cracking resistance of the aged asphalt binder also improved. The bio-rejuvenation helped reduce the oxygenated-group peak-area intensities of the aged asphalt. The results of the component analysis show that the asphaltene content of the aged asphalt reduced by adding the bio-rejuvenator. The molecular-weight-distribution patterns were further examined. The results show that the bio-rejuvenator helps increase the medium-weight molecular content whereas the high-weight molecular content remains unchanged. [ABSTRACT FROM AUTHOR]

This paper presents comprehensive research work on the crack initiation behavior of Semi Flexible Pavements (SFP) with the help of a one-way coupled multiscale modelling approach. The study focuses on elucidating the influence of layer interface conditions on potential cracking patterns under different temperature conditions. By integrating material properties at both local (mixture) and global (pavement) scales using a local de-homogenization approach, the interlocking effect was addressed within the asphalt binder's mesoscale properties. CT-image based mesostructure was employed to reconstruct the Representative Volume Element (RVE). Cohesive Zone Model (CZM) was utilized to simulate cracking initiation within the RVEs, with simulation results validated against practical engineering inspections. Additionally, a potential macroscopic failure index was introduced for SFP. It was found that the typical macroscopic failure indexes utilized for AC pavement may not be suitable for SFP due to the higher degree of heterogeneity. Analysis showed that SFP layer's coarse aggregate and cement grout at the bottom may experience compressive stress, while asphalt binder beneath the tire load may face high tensile stresses. Regardless of the interface conditions, top-down cracking was found to be the dominating failure mode in SFP. Besides, the vulnerable area in bonded interface SFP shifts from under tire load to the adjacent area with the rise in pavement temperature, while bottom-up cracking may appear only in unbonded interface SFP under low temperature conditions. Subsequent analysis demonstrated that top-down cracking is prominent in bonded interface SFP, especially at higher temperatures, compared to unbonded interface SFP. It is expected that critical observations for SFP highlighted above will certainly help in understanding critical failure modes and, hence, designing and constructing durable SFP structures. • A one-way coupled multiscale modelling approach considering interlocking effect was developed. • The interlocking effect was addressed using a local de-homogenization method. • The cracking initiation form of SFP was simulated and validated by pavement inspection. • A potential macro-mechanical failure index was proposed for SFP. [ABSTRACT FROM AUTHOR]

In the past three decades, researchers have engaged in the relationship between the composition, macro performance, and microstructure of asphalt. There are many research results in the use of atomic force microscopy (AFM) to study the microstructure and related mechanisms of asphalt. Based on previous studies, the performance of asphalt from its microstructure has been observed and analyzed, and different evaluation indices and modification methods have been proposed, providing guidance toward improving the performance of asphalt materials and benefiting potential applications. This review focuses on the typical application and analysis of AFM in the study of the aging regeneration and modification properties of asphalt. Additionally, this review introduces the history of the rheological and chemical testing of asphalt materials and the history of using AFM to investigate asphalt. Furthermore, this review introduces the basic principles of various modes of application of AFM in the microstructure of asphalt, providing a research direction for the further popularization and application of AFM in asphalt or other materials in the future. This review aims to provide a reference and direction for researchers to further popularize the application of AFM in asphalt and standardize the testing methods of AFM. This paper is also helpful in further exploring the relationship between the microstructure and macro performance of asphalt. [ABSTRACT FROM AUTHOR]

• A laboratory test was developed to evaluate the thermal resistance of waterproof bonding materials. • The interfacial thermal resistance parameter was determined by the laboratory test and numerical simulation. • Interlayer residual stress remain in the SBDP after the high-temperature pavement paving. • The calculated maximum interlayer residual stress based on the CZM was 7.3 kPa. The interlayer shear stress in the steel bridge deck pavement (SBDP) and interlayer shear performance of waterproof bonding material change significantly during the gussasphalt mixture (GAM) paving, and interlayer residual stress may remain in the SBDP after the paving, which can affect the long-term performance of SBDP. The interfacial thermal resistance (ITR) parameter was proposed to represent the thermal resistance performance of waterproof bonding material firstly. A laboratory test and numerical simulation were carried out simultaneously through simulating the temperature variations of OSBD and GAM pavement during the paving, and the ITR values for three common waterproof bonding materials were determined by the least square method. The direct shear test was used to measure the shear performance variations of waterproof bonding layer during the GAM paving. The cohesive zone model (CZM) in the finite element (FE) method was used to characterize the interlayer shear performance variations of waterproof bonding layer during the paving, and the interlayer residual stress in the SBDP was calculated by the numerical simulation. The results showed that the ITR of the methyl methacrylate (MMA) bonding material is about two times that of HYPER-PRIMER (HYP) epoxy resin, and the ITR of 2910-type epoxy asphalt bonding material approximates zero. The waterproof bonding material with higher ITR values can reduce the highest temperature of steel bridge deck and interlayer residual stress during the paving to some extent, and the maximum interlayer residual stress after the gussasphalt pavement paving reaches 7.3 kPa. [ABSTRACT FROM AUTHOR]

Semi-flexible pavement (SFP) is characterized by injected cementitious grout within porous asphalt (PA) matrixes to improve anti-rutting performance. The grouting rate is a key factor to ensure longevity and performance of SFP that require precise and non-destructive in-situ measurements. No practical approach has been built in both literature and field applications. This research proposed an automatic method for determining the SFP grouting rate, namely the Leng-Wang-Sui (LWS) model, a novel SFP dielectric constant prediction model derived from electromagnetic (EM) mixing theory. The validity of the proposed method was substantiated through a sensitivity analysis, numerical simulations of meso-scale ground-penetrating radar (GPR)-SFP models, and laboratory tests. Results verify the method's capability to accurately predict the in-situ grouting rate of SFP, demonstrating an average estimation error below 7 %. A practical workflow of using GPR in conjunction with the LWS model for on-site assessments of SFP grouting rate was recommended for real-world applications. • A novel composite dielectric model of semi-flexible pavement. • Non-destructive evaluation of in-situ grouting rate of semi-flexible pavement. • Meso-scale electromagnetic models of semi-flexible pavement system. • A workflow using the proposed model and ground-penetrating radar. [ABSTRACT FROM AUTHOR]

Mortar thickness plays a crucial role in the adhesion/cohesion properties of mortar, and its distribution further affects the stress response, mechanical, durability, and fatigue performance of asphalt mixtures. However, the random distribution of mortar thickness (RDMT) in asphalt mixtures remains inadequately characterized. X-ray computed tomography (CT), digital imaging processing, and sampling mask with different orientations are employed to determine the mortar thickness in seven asphalt mixture designs. These mixtures include open-graded, dense-graded, and gap-graded asphalt mixtures with nominal maximum aggregate size (NMAS) of 13.2 mm, 16 mm, and 19 mm. Three segmentation methods (parallel line, sector, and ring segmentation) with different segmentation numbers are applied on CT images to investigate the RDMT. The variance of mortar thickness, coefficient of variation, and range of mortar thickness are used to evaluate the RDMT. The orientations of the sampling mask have a negligible impact on the distribution of mortar thickness. In contrast, the segmentation methods and segmentation numbers significantly affect the evaluation results of RDMT. Parallel line segmentation with 36 segments demonstrates the best potential and is recommended for characterizing RDMT. The average mortar thickness (T average) and RDMT are increased with the increasing NMAS, with a particularly significant increase observed when NMAS changes from 13.2 mm to 16 mm. The gap-graded asphalt mixtures exhibit the greatest T average and RDMT when comparing to the dense-graded and open-graded asphalt mixtures. Furthermore, the T average and RDMT are smaller at the top and bottom of the specimen compared to the middle section. At the middle section, the T average and RDMT exhibit fluctuations with multiple peaks, and the distance between two adjacent peaks is approximately equal to the NMAS. This study provides a simplified method to characterized the complicated RDMT and lays a foundation for investigating the role of RDMT in the meso-mechanics of asphalt mixtures. • A novel method for characterizing RDMT was proposed. • The influence of NMAS and asphalt mixture types on the RDMT was investigated. • The RDMT along the height of specimen was evaluated. [ABSTRACT FROM AUTHOR]

To improve the bonding quality between the sleeper and asphalt block used in the asphalt elastic cured track bed, a novel epoxy asphalt mortar (EAM) was designed in this study. The optimal dosage of EAM was determined as 17 kg·m-2 through laboratory tests. Besides, to understand the bonding quality in depth, the bonding performance of two kinds of sleeper-asphalt block composite structures under different conditions were investigated through interfacial shear test and pull-out test, and the results show that the bonding quality between sleeper and epoxy asphalt mixture using designed EAM is better than that between sleeper and styrene–butadiene–styrene/crumb rubber (SBS/CR) composite modified asphalt mixture. Meanwhile, bonding qualities decrease in an exponential trend with the increase in temperature. Besides, an FE model using a cohesive contact approach at the interface was established and validated to evaluate the bonding performance during the long-term service and lifting process. The differences among static lifting parameters and dynamic lifting parameters were evaluated and the optimal lifting speed was selected as 0.9 m/s. The results also show that the sleeper-epoxy asphalt mixture composite structure has better bonding performance at most conditions and this structure was selected as the ideal structure for construction. • A method of evaluating bonding quality between sleeper and asphalt blocks in elastic asphalt cured track was established. • The bonding quality under different working conditions and different construction processes were researched in detail. • A method of connecting laboratory bonding tests and an FE model was established. [ABSTRACT FROM AUTHOR]

• The fracture modes of SCB specimen at different temperature and with different initial crack length were discussed. • The relationship between fracture energy and initial crack length at different temperature were discussed. • The reasonability of using fracture energy as critical parameter in researching crack growth was validated. • A XFEM model of pavement with initial reflective crack was established using fracture energy obtained by laboratory test. Reflective cracking is one of the main failure mode of pavement structures, resulting in structure deterioration and reduced traffic safety. This study investigated the cracking behavior of reflective cracks using semi-circular bending (SCB) specimens and fracture tests were conducted to obtain fracture energy, which is the critical parameter of facture calculation, and the reasonability of fracture energy was validated using a numerical model of SCB specimen. Then, a numerical model of typical pavement structure was established and cracking behavior of reflective cracks and related parameters influencing cracking were investigated in detail. The simulation results indicate the main form of reflective crack is mode I and mode II mixed crack, among which mode I takes the dominant position. Among the four investigated influence factors, overloading and long-time loading have a significant influence on the expansion of reflective cracks, while the temperature mainly influences the expansion of mode I crack. The traffic speed mainly affects the direction of crack expansion, while other factors do not have a significant effect on it. [ABSTRACT FROM AUTHOR]

• Clarify the effects of mixture gradation and polishing on nanoindentation results. • Characterize the age-hardening behavior of asphalt mixtures using nanoindentation. • Describe the vertical aging gradient in asphalt mixtures by nanoindentation. Understanding the aging behavior of asphalt mixtures is of great significance to the design, construction and maintenance of asphalt pavements. Numerous studies have been conducted on the aging phenomenon and its effects on mixture properties. However, conventional testing methods focus mainly on the global view or average value of the performance of aged mixtures, while the inner aging gradients are seldom addressed. The aging gradient, referring to the differences of aging effects in asphalt mixtures due to different accessibilities to aging conditions, represents the true aging behavior of asphalt mixtures. Hence, a micromechanical testing technique, nanoindentation, was used in this paper to investigate this issue. The effects of mixture gradation and polishing in sample preparation process on nanoindentation results were explored first. Then the vertical changes of modulus of asphalt mastic in asphalt mixture samples were characterized by nanoindentation to describe the aging gradient in different aged mixture samples. Dynamic modulus test was also performed for data supplement and comparison. Results show that gap-graded mixtures are suitable for nanoindentation test and a careful and standard polishing treatment will not affect the reliability of nanoindentation data. Nanoindentation can well characterize the age-hardening behavior of asphalt mastic and the aging gradient in long-term aged asphalt mixtures is approximately in a logarithmic curve form. Nanoindentation modulus results indicate that 8d of laboratory long-term aging in this paper can only affect the upper sections of dense asphalt mixtures. This paper suggests that nanoindentation can achieve a quantitative, mechanical and precise characterization of aging gradient in asphalt mixtures and is therefore promising in further research of asphalt materials. [ABSTRACT FROM AUTHOR]

Abstract Profound progress has been made in bio-rejuvenators to enhance aged asphalt's low temperature performance and reduce its high temperature viscosity. However, limitation still exists in the knowledge how long service life of rejuvenated asphalt is and whether regeneration is effective since aging behavior of rejuvenated asphalt is neglected. Furthermore, aging evaluation is based on different tests dependent on temperature, which may lead to various results. This study aims to evaluate the aging behavior of bio-rejuvenated Pen70 and SBS modified asphalts using internal aging indexes that characterize the physical property. Original Pen70 and SBS asphalts under identical aging conditions were set as the control group. Fourier transform infrared spectroscopy test (FTIR) was conducted to quantify aging extent through oxidation aging functional groups. Activation energy was achieved through rotational viscometer (RV). Dynamic shear modulus was acquired through dynamic shear rheological test (DSR) and characterized by two springs, two parabolic elements, and one dashpot (2S2P1D) model. For both Pen70 and SBS, the two potential aging indexes related with activation energy and viscosity of dashpot separately were found linearly correlated with related chemical aging functional groups. Through comparison, it indicates that bio-rejuvenation was a process of physical blending. It couldn't restore the crosslinking structures of SBS polymers. Besides, the physical property of bio-rejuvenated Pen70 degenerated faster, while that of bio-rejuvenated SBS stayed stable. A benefit period was proposed for the rejuvenation of Pen70 while the rejuvenation of SBS was not bound by time. Further work is needed to validate findings in the present study. Graphical abstract Image 10385 [ABSTRACT FROM AUTHOR]

Determining the causes of gas production difference among wells and regions is crucial for future coalbed methane (CBM) exploration and development. Combined with gas content and equivalent drainage radius (ER), the vertical characteristics that different coal texture types overlaid are researched and compared between the north and south regions in the Zaoyuan area of Shizhuangnan Block, Southern Qinshui Basin. The results indicate that the vertical relationship of different coal textures has a great impact on gas/water production. Thicker granulated coal may contribute to adsorb more gas, but may also increase the possibility of blocking the seepage channel with coal powder in the coals. CBM in granulated coals could flow into the wellbore through the fractures in the upper and lower cataclastic or undeformed coals, and the mudstone contact directly below the granulated coals in the north may restrict gas production, as mudstone could obstruct the seepage passage that CBM in granulated coal flows downward. [ABSTRACT FROM PUBLISHER]

• The acoustic emission technology is used to monitor and analyze the damage of cement grouted asphalt mixture in the whole process. • Flexible anti-rutting material is used as control group to analyze the cracking characteristics of cement grouted asphalt mixture. • The cracking stages of the cement grouted asphalt mixture are divided, and the cracks are classified and time-history analyzed according to macroscopic and microscopic, shear and tensile. Cracking is one of the main diseases of cement grouted asphalt mixture (CGAM). This paper aims to disclose the whole process failure characteristics of CGAM under different loads. Three types of tests under acoustic emission monitoring were designed to observe the performance of CGAM under indirect tension, bending tension and compression. Stone matrix asphalt (SMA) was used as the control group. The results show that the failure process of CGAM can be divided into three stages. Large damage will be produced in one or more short periods. The cracking of cement mesh is one of the main factors to form cracks in CGAM, and its brittleness leads to the proportion of macro cracks of CGAM in each stage being greater than that of SMA. The proportion of shear failure of CGAM is higher than that of SMA, so more attention should be paid to its shear resistance in material design. [ABSTRACT FROM AUTHOR]

• An equivalent dynamic modulus of asphalt binder was introduced to incorporate the interlocking effect in the model. • Temperature plays a significant role in the damage process of SFP composite. • The macro distribution of damage degree of SFP primarily depends on cement grout. Poor cracking resistance is a widely known concern of semi-flexible pavement (SFP). However, most of the previous studies on SFP composite have focused on the crack evolution at the macroscale, while the corresponding studies on the mesoscopic damage process are very limited. Moreover, the cracking resistance of SFP composite was found to be significantly affected by temperature, but quantitative analysis on such effect is missing. To fill the knowledge gap, this study aims to understand the role of temperature on the mesoscale damage process of SFP composite using the finite element method (FEM). The cohesive elements for the asphalt binder and cement grout phases, and the adhesive element along the interface between asphalt and aggregate and along the interface between asphalt and cement grout were considered in the simulation process. An equivalent dynamic modulus of asphalt binder was also introduced to incorporate the interlocking effect in the analysis process. Similarly, the pull-off test was performed to incorporate the role of interface strength in the damage process. The change in the roles of different phases (asphalt binder or cement grout) and interfaces (cement grout-asphalt binder or asphalt binder-aggregate) in SFP composite in the damage evolution process with the change of temperature was clearly identified. Overall, this research is a steppingstone towards better understanding of the cracking mechanism of SFP at the mesoscale, which can help develop SFP composite with improved cracking resistance. [ABSTRACT FROM AUTHOR]

In this study, a new approach “sulfur-oil agglomeration” for gold flotation was put forward to recover gold particles in laboratory and industrial scale experiments. The optimum recovery of gold was obtained by adding (NH 4 ) 2 S 2 O 3 , oil emulsions and sulfur into the mill, together with butyl xanthate as the collector in weak acidic pulp adjusted by H 2 SO 4 . Fundamental concepts of gold flotation were considered, including the sulfur-oil-gold agglomeration mechanisms and the role of (NH 4 ) 2 S 2 O 3 . The possible mechanism had been put forward: (1) nature of (NH 4 ) 2 S 2 O 3 is complex, it renders the oxidized gold surface cleaned, the exposed fresh surface shows strong natural oleophilicity; (2) in weak acidic pulp, S decomposed from (NH 4 ) 2 S 2 O 3 , a highly hydrophobic/oleophilic material, agglomerated with gold; (3) then the oil droplets overspread the gold surfaces and the collision of these oil wetted particles caused formation of “liquid bridges” each upon them. As a result, the fine gold particles in the beginning were converted to the masses in the form of sulfur-gold-oil which were bonded together by liquid bridges. Meanwhile, the sulfur could strengthen the adsorption of collectors on gold surface, as well as the floating size range of gold is widen, and the recovery of gold is significantly improved. Industrial trials conducted at Yunnan, China showed that an average gold recovery of 87.39% into a concentrate assaying 25.84 g/t Au from a feed of 1.8–3.0 g/t could be achieved by the aid of sulfur-oil agglomeration method. [ABSTRACT FROM AUTHOR]

As a new type of railway structure, the elastic trackbed can avoid the inherent limitations of railway ballast tracks and slab tracks. Therefore, it is of great significance to provide excellent materials for the elastic trackbed. In this paper, the feasibility of applying crumb rubber asphalt mixture (CRM) to the railway trackbed is preliminarily investigated by evaluating the mechanical properties of CRM. The static modulus, vertical deformation and lateral stability of CRM for the elastic trackbed are characterized via the uniaxial compression test as well as the interfacial shear test. In addition, via the dynamic creep test, the temperature susceptibility, the viscoelastic behaviours as well as the creep compliance master curve of CRM are studied. The uniaxial compression results show that the stiffness of CRM with 3 wt% and 6 wt% crumb rubber particles decreases compared with the ordinary asphalt mixture. And the vertical deformation can also meet the requirements of the elastic trackbed. Furthermore, it is shown from the shear test that the interfacial strength, which presents a linear relationship with temperature, can provide satisfactory lateral stability of the elastic trackbed. Additionally, the dynamic creep test results reveal that the addition of 3 wt% crumb rubber will not lead to excessive accumulation and the increased temperature susceptibility of permanent deformation at high temperature. The viscoelastic parameters gained from the dynamic creep test also show that asphalt mixture with 6 wt% crumb rubber particles shows the worst resistance to deformation despite having the best recovery performance. Finally, the creep compliance master curve of CRM between 10-2 to 109 domain can be obtained by horizontally shifting the creep curves at high temperature. And the horizontal shift factors can be gained. Then, the long-term deformation of the elastic trackbed under the dynamic train load can be predicted by using the equivalent conversion loading time from the short-term dynamic creep test results at 25 ℃ and 0.25 MPa. [ABSTRACT FROM AUTHOR]

Mixture segregation is a common defect in the construction of epoxy asphalt mixture (EAM) deck pavement. The segregation can affect the compaction quality of EAM deck pavement, while the compaction action can also change the segregation degree in the EAM. Therefore, the appropriate compaction technique can decrease the mixture segregation. The objective of this study is to investigate the mutual effect of mixture segregation and EAM compaction. To achieve this goal, the Superpave gyratory compaction (SGC) test was conducted, and a field compaction DEM (Discrete element method) model for EAM on the steel bridge deck was developed using a partitioned deposition method, to study the segregation characteristics of EAM during the compaction. Results show that the partitioned distribution segregation of aggregate in the EAM decreases first and then increases with the increase of gyration compactions. As a thermosetting material, the segregation is more likely to occur in the lowly cured EAM during the compaction process. In the field compaction, the initial vertical distribution segregation of loose EAM has a significantly negative effect on the compaction quality of EAM deck pavement, while the compaction action could also influence the segregation degree of EAM. Under the over repeated compaction, the increasing 1segregation degree of fine EAM particles and too tight contact between EAM particles make the extrusion separation of asphalt mastic between the coarse particles, which could result in the surface bleeding problem. The findings from this study are helpful to decrease mixture segregation and improve compaction quality of EAM deck pavement.. [ABSTRACT FROM AUTHOR]

Recycled from waste tires, crumb rubber (CR) is a common additive material using in transport infrastructures to improve the mechanical performance of asphalt mixture. The styrene-butadiene-styrene (SBS) and CR composite modification technology were employed to prepare SBS/CR composite modified asphalt (CMA) binders. To study the effect of CR contents and control modes on the fatigue performance of asphalt binders, the Dynamic Shear Rheometer (DSR) tests, including stress/strain sweep tests and controlled-stress/strain time sweep tests, were conducted to calculate the fatigue crack density as loading cycles. Based on the test data, the fatigue crack density evolution and the modified Paris' law were used to characterize the fatigue performance of SBS/CR CMA binders. A unified fatigue parameter was proposed to evaluate the fatigue resistance and optimize the CR content of SBS/CR CMA binders under two control modes. Results demonstrated that the fatigue crack density only experienced two stages (the crack initiation stage and the steady growth stage) under the controlled-strain loading, while the asphalt binder sample shows obvious structural failure (e.g., stepping into the unsteady growth stage) under controlled-stress loading. The smaller value of the proposed index, ln A / (n + 1) , indicated the better capacity of fatigue crack resistance and that of a certain type of asphalt binder under two control modes were almost identical. Furthermore, the value of SBS/CR CMA binder with 40 wt% CR was −6.81 showing the best fatigue performance among these asphalt binders, and the CR contents and the values of proposed index followed a linear relationship. [ABSTRACT FROM AUTHOR]

Residual waste toner (WT), which is abundantly generating with modern industry, is a potential green resource that can be used as an asphalt modifier for better engineering performance and cost-saving. This study is conducted to comprehensively evaluate the feasibility of using WT as an asphalt modifier considering various rheological properties of the modified binder. Four different WT modified asphalt are prepared (with WT contents of 3%, 6%, 9%, and 12%). The properties of the modified binder were investigated through a series of rheological tests including the conventional binder specification tests (penetration, softening point, ductility, and flash point), multiple stress creep recovery (MSCR), and Bending Beam Rheometer (BBR) tests. Testing results indicated that the incorporation of WT can improve the rheological properties of the asphalt binders at low and high temperatures regardless of the WT contents. Besides, WT was shown a positive impact on fracture and bonding performances. It is noted that asphalt binders containing up to 12% of WT had a significant improvement on high-temperature, intermediate temperature fracture, low-temperature cracking, and moisture sensitivity properties. In the end, the present research shows the residual WT as a value-added modifier is a promising solution with both environmental and engineering merits. [ABSTRACT FROM AUTHOR]

Semi-flexible pavement (SFP) is widely used in recent years because of its good rutting resistance, but it is easy to crack under traffic loads. A large number of studies are aimed at improving its crack resistance. However, the understanding of its fatigue resistance and fatigue-cracking mechanism is limited. Therefore, the semi-circular bending (SCB) fatigue test is used to evaluate the fatigue resistance of the SFP mixture. SCB fatigue tests under different temperature values and stress ratio were used to characterize the fatigue life of the SFP mixture, and its laboratory fatigue prediction model was established. The distribution of various phases of the SFP mixture in the fracture surface was analyzed by digital image processing technology, and its fatigue cracking mechanism was analyzed. The results show that the SFP mixture has better fatigue resistance under low temperature and low stress ratio, while its fatigue resistance under other environmental and load conditions is worse than that of asphalt mixture. The main reason for the poor fatigue resistance of the SFP mixture is the poor deformation capacity and low strength of grouting materials. Furthermore, the performance difference between grouting material and the asphalt binder is large, which leads to the difference of fatigue cracking mechanism of the SFP mixture under different conditions. Under the fatigue load, the weak position of the SFP mixture at a low temperature is asphalt binder and its interface with other materials, while at medium and high temperatures, the weak position of the SFP mixture is inside the grouting material. The research provides a basis for the calculation of the service life of the SFP structure, provides a reference for the improvement direction of the SFP mixture composition and internal structure. [ABSTRACT FROM AUTHOR]

• A polymer modified bio-derived rejuvenator (PMBR) was prepared. • PMBR has satisfactory ability to rejuvenate the anti-cracking and anti-fatigue performance of aged bitumen. • PMBR contains no severe side-effects on the high temperature performance of rejuvenated bitumen. PMBR renders better elastic response to aged bitumen. • The polymer and crosslinking agent replenished by PMBR can react with the initially destroyed SBS segment in aged SBS modified bitumen. Then the network structure can be restored. In this paper, a polymer modified bio-derived rejuvenator (PMBR) consisting of bio-oil, polymer modifier, and other additives (plasticizer, cross-linking agent) was investigated. The regeneration performance of PMBR on aged base and SBS modified bitumen was compared with that of commercial rejuvenator (CR) and bio-based rejuvenator (BR). The anti-cracking, anti-fatigue, anti-rutting and anti-moisture performance of aged base and SBS modified bitumen rejuvenated by CR, BR, as well as PMBR were evaluated via Dynamic Shear Rheometer (DSR) tests. The morphology, as well as the change of molecular functional groups of aged base and SBS modified bitumen rejuvenated by PMBR were studied by Fluorescence Microscopy (FM) and Fourier Transform Infrared Spectrum (FTIR). Glover-Rowe diagram results manifest that PMBR could restore the anti-cracking performance of aged bitumen to the level of virgin binder. Black diagram results show that PMBR rendered satisfactory elastic performance. Moreover, it is obtained from Linear Amplitude Sweep (LAS) results that PMBR performed better than conventional rejuvenators in reducing the damage rate and increasing the N f of aged bitumen. Additionally, Multiple Stress Creep Recovery (MSCR) results reveal that PMBR contained no severe side-effects on the high temperature performance, and rendered better elastic recovery to aged bitumen. The Shear Test results show that PMBR rejuvenated bitumen contained better anti-moisture ability as well as better network structure strength among all rejuvenated bitumen. Finally, the reaction between PMBR and aged SBS modified bitumen and the restoration of network structure was revealed via analyzing the morphology studied by the FM test, and characterizing the the C─S stretching vibrations and ─CH═CH─ vibrations in polybutadiene block obtained from the FTIR test. It is verified that the polymer and crosslinking agent replenished by PMBR reacted with the originally destroyed SBS segment in aged SBS modified bitumen. Then the network structure was restored, which could explain the rheological properties of aged bitumen rejuvenated by PMBR. [ABSTRACT FROM AUTHOR]

• An innovative precise low-intensity magnetic separator (PLIMS) was designed and manufactured. • The design parameters of the magnet assembly and operational parameters of PLIMS were optimized. • The remnant flux density of the magnet assembly was designed to gradually increase from low to high. • The principle of PLIMS was explained by simulating the dynamic capture process of the magnetic particles. A wet low-intensity magnetic separator (LIMS) is the workhorse for winning magnetite from a slurry. However, the issue with optimizing LIMS is the balance between attracting too much material and obtaining mixed grains of extremely low-grade material (less than 20 vol% magnetite) in the concentrates and attracting too little material and losing the fine liberated magnetite to the tailings. In this study, an innovative precise low-intensity magnetic separator (PLIMS) was designed and optimized based on a multiphysics numerical model. The design parameters of the magnetic assembly and operational parameters were designed and optimized by predicting the separation performance and particle dynamic trajectory of the PLIMS. In particular, the remnant flux density of the magnet assembly was designed to gradually increase from low to high along the flow direction of the slurry, so that the magnetic particles were subjected to precise magnetic force during the separation process. When the magnetic force is greater than the competitive forces, the magnetic particles are captured on the surface of the drum. Then, the captured particles with different liberation degrees and particle sizes are taken out of the separation zone via rotating drum one by one and become concentrated products of multiple grades. The aim of the process is to capture the high liberation magnetite into the main concentrates to obtain high-grade concentrate products, while also capture the low-grade intergrowth particles into the minor concentrates as much as possible to obtain higher recovery. Furthermore, this principle of magnetic separation of PLIMS was explained by simulating the dynamic capture process of the magnetic particles. To verify whether the design concept of gradient magnet assembly (GMA) has advantages, another uniform magnet assembly (UMA) with the same remnant flux density of all permanent magnets was designed. Comparative studies of the magnetic field distribution and magnetic separation performance of GMA and UMA show that PLIMS of the GMA has more significant separation performance. Finally, a laboratory-level PLIMS with a drum diameter of 300 mm (ϕ 300-PLIMS) was manufactured based on all the optimization studies above. By comparing the experimental results with simulated results, the accuracy of the PLIMS recovery and grade prediction results were verified. [ABSTRACT FROM AUTHOR]

• Viscosity of asphalt rubber is affected by the liquid phase and the particle effect. • Particle effect dominates the viscosity under some crumb rubber contents. • Viscosity of liquid phase is more reliable asphalt mixture workability parameter. Previous studies have documented the disconnect between the rotational viscosity of asphalt rubber (AR) and the workability of AR mix. There is a possibility that the particle effect of crumb rubber modifier (CRM) particles within AR causes this phenomenon. This study measured the viscosities of ARs and the corresponding liquid phases at three temperatures. The workability of the corresponding AR mixes was evaluated using the number of gyrations of Superpave Gyratory Compactor (SGC) samples. The changes on AR caused by the CRM contents were measured using Gel permeation chromatography (GPC) test. The experimental results revealed that the rotational viscosity of the AR liquid phase is more suitable to be used as a workability indicator. In addition, thresholds of CRM content were reported. Once the threshold is exceeded, the increase in AR viscosity is only caused by the increase in CRM particle effect and there is no detectable CRM/asphalt interaction. [ABSTRACT FROM AUTHOR]