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Epoxy asphalt concrete (EAC) is a widely used steel bridge deck pavement (SBDP) material. Due to the curing reaction, the EAC-based material needs a long curing period before opening to traffic, which in an inconvenience in the construction of SBDP. This study developed a cold mix high-early-strength (CHES) epoxy asphalt through the design of a compatilizer and curing agent system. The optimum formula of CHES epoxy asphalt was determined through a series of laboratory tests. By comparison of the performances of CHES EAC and some conventional EACs for SBDP, it was found that the developed CHES epoxy asphalt can significantly reduce the curing period, and the pavement performance of CHES EAC is, overall, excellent for application in SBDP. In addition, the sufficient allowable construction duration shows that the CHES EAC has a good construction workability.
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Construction and demolition waste material is of great potential for use in pavement engineering. This paper aims to investigate the feasibility of ceramic waste aggregate (CA) used in cooling asphalt pavement through a series of test methods and simulation techniques. Stone mastic asphalt (SMA) containing 10%, 20%, 30%, 40%, and 50% coarse ceramic waste aggregate (CASMAs) was first designed using the Marshall method. Afterward, the road performance and thermal insulation performance of the five different CASMAs were assessed by a comprehensive lab test, including a wheel rutting test, moisture susceptibility test, bending beam test, fatigue beam test, and indoor thermal insulation test. Finally, a 2D finite-element (FE) model was developed to investigate the transient thermal field and rutting deformation response of the cooling asphalt pavement with CASMAs. Results show that CASMAs experienced degradation of rutting resistance, moisture susceptibility, and anti-cracking performance while still meeting technical requirements with CA content of up to 40%. On the other hand, CASMAs can cool the pavement's temperature by 11.5 °C at the bottom of asphalt layers. The permanent rutting deformation of cooling asphalt pavement was 45.36% smaller than that of conventional asphalt pavement without CASMAs. Based on the test results and numerical simulation results, the optimum content of ceramic waste aggregate in stone mastic asphalt was recommended as 40%.
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High percentage reclaimed asphalt pavement (RAP) is prevailing in pavement engineering for its advantages in sustainability and environmental friendliness, however, its fatigue resistance remains a major concern. Fine aggregate matrix (FAM) is a crucial part in the fatigue resistance of asphalt mixtures with high RAP content. Hence, the linear amplitude sweep (LAS) test of FAM has been developed to study the fatigue resistance of asphalt mixtures. However, the torsional loading mode of the LAS test with a dynamic shear rheometer (DSR) is a limitation to simulate traffic load. In this paper, an alternative LAS test for FAM with high RAP content was proposed. Beam FAM specimens were tested using a dual-cantilever flexural loading fixture in a dynamic mechanical analyzer (DMA). To investigate the influence of RAP content and the rejuvenating agent (RA), four kinds of FAM mixes were tested with this method to study their fatigue resistance. The test results suggested that the repeatability of this alternative approach was reliable. A fatigue failure criterion based on maximum C × N was defined. Then, fatigue life prediction models based on viscoelastic continuum damage (VECD) analysis were established according to the LAS test results and validated by a strain-controlled time sweep (TS) test. It turned out that as RAP content increased, the modulus of FAM would be significantly raised, accompanied with a drop in the phase angle. The fatigue life of FAM would be greatly shortened when the RAP binder replacement rate reached 50%. Adding RA could considerably improve the dynamic properties of FAM mixes with high RAP content, resulting in a decrease in modulus, increase in phase angle and elongating fatigue life, but could not recover to the level of virgin binder.
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OBJECTIVES: This article aims to model fault in e-bike fatal crashes in a county-level city in China. METHOD: Three-year crash data are retrieved from the crash reports (2012-2014) from the Taixing Police Department. A mixed logit model is introduced to explore significant factors associated with fault assignment, as well as accounting for similarity among fault assignment and heterogeneity within unobserved variables. RESULTS: The modeling results indicate some interesting new findings. First, precrash behaviors of both drivers and e-bike riders are found to be significant to fault assignment. Second, bike lane and median type are significantly associated with e-bike rider fault commitment. Third, specific groups of e-bike riders (low-educated and older) and drivers (heavy good vehicles) are more likely to be at fault in e-bike crashes. Last, crash location and the built environment have significant correlations with faulty behaviors of e-bike riders. CONCLUSIONS: Safety countermeasures are proposed including (1) the deployment of traffic design and control elements including physically separated bike lanes, medians, video surveillance systems for e-bike riders, and left-turning treatments for nonmotorists (e.g., a 2-step e-bike left turning); (2) the amendment of the current traffic regulations on drunk e-bike riders and child e-bike passengers; (3) the development of a license system for specific e-bike rider groups (older and low-educated) and a safety campaign for drivers (to increase safety awareness when parking on-street or driving heavy good vehicles). Some interesting future research topics are also suggested: e-bike riders' behaviors at unsignalized intersections and mid-block openings, e-bike safety in suburban areas, and an in-depth study of the effect of the built environment on e-bike safety.
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Accidentes de Tránsito/estadística & datos numéricos , Conducción de Automóvil/psicología , Motocicletas/estadística & datos numéricos , Medición de Riesgo , Asunción de Riesgos , Adulto , Anciano , China , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Notch family proteins have been reported to be associated with the initiation and development of various types of tumors. The present study used a prospective design to investigate the role of Notch proteins as novel biomarkers that are capable of predicting the survival outcome for patients with non-small cell lung cancer (NSCLC). The protein expression of Notch 1, Notch 3 and their ligands, Jagged 1 and Delta-like 4, was examined using immunohistochemistry in NSCLC tissues and adjacent non-cancerous lung tissues from 101 patients who underwent surgical treatment. The expression was also correlated with clinicopathological parameters and overall survival (OS). High Notch 1 protein expression was observed in 55.4% (56/101) of NSCLC samples and high Notch 3 expression was observed in 53.5% (54/101). The nuclear expression of Notch 3 was significantly associated with the lymph node status (P=0.0026) and tumor-node-metastasis (TNM) stage (P<0.0001), while the coexpression of Notch 1 plus Notch 3 was associated with lymph node status (P=0.0056), TNM stage (P=0.0001) and the histological grading (P=0.0359). In the survival analyses, the high expression of Notch 1 and Notch 3 exhibited an additive effect toward a poorer OS compared with a subtype with low coexpression for the two proteins (P<0.001), with high nuclear Notch 3 expression in the NSCLC patients maintaining independent prognostic significance for the outcome on multivariate analysis. These data further demonstrate a central role for Notch signaling in NSCLC and the significance of Notch 3 as a prognostic indicator of a poorer survival for patients with resected NSCLC.