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Changes in ambient temperature significantly affect the flexural properties of bamboo scrimber. From the perspective of structural safety, temperature is one of the most important conditions to be considered when using structural components made of bamboo scrimber. This experimental study investigated the flexural performance of bamboo scrimber across a broad temperature range of −30 °C to 250 °C, providing essential data for its use as a structural member under different temperature conditions. Through a series of tests conducted at different temperature conditions with utilization of scanning electron microscopy, the damage modes and failure mechanism of bamboo scrimber were analyzed at both macroscopic and microscopic levels. It was found that the failure modes of bamboo scrimber under different temperature conditions were mainly categorized as simple tensile fracture damage, split tensile damage and brittle tensile fracture damage, in which the brittle tensile fracture damage only occurred in the specimens at a temperature of 250 °C. In general, the flexural strength and modulus of elasticity decrease with increasing temperature; when the temperature was increased from 20 °C to 250 °C, the specimens' flexural strength and modulus of elasticity decreased by 87.95 % and 90.25 %, respectively. Microscopic analysis revealed that these variations were correlated with alterations in the shape, structure and composition of the internal cells. Moreover, based on the Hognestad model, a mathematical relationship model between the load-displacement curves of bamboo scrimber and the temperature was derived, which can accurately predict the flexural load capacity of bamboo scrimber under varying temperature conditions. • Flexural properties of bamboo scrimber are investigated under low to high temperature. • Microscopic analysis is carried out with a scanning electron microscope. • Temperature influence coefficient equations for strength and modulus are proposed. • Mathematical model between load-displacement curves and the temperature is derived. [ABSTRACT FROM AUTHOR]

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

Highlights: [•] Hydrocarbon as means of limiting drying shrinkage in cement mortar. [•] Microstructural matrix was observed through SEM. [•] Hydrocarbons fill-up voids and microstructural cracks in mortar. [•] Drying shrinkage of mortar decreases with inclusion of hydrocarbon. [ABSTRACT FROM AUTHOR]

• The macroscopic and microscopic properties of concrete were compared and analyzed under different temperatures and subsequent different cooling methods. • The acoustic emission (AE) phenomenon of concrete after high temperature treatment is different from that of the normal temperature condition. • Under the condition of 300 °C high temperature and air cooling condition, the uniaxial compressive strength of precast crack concrete specimen was improved. • Mechanical characteristics of concrete containing pre-existing crack under different temperatures and subsequent different cooling methods are studied. In order to investigate the mechanical properties and crack propagation of concrete after high temperature, the concrete specimens with different angles of prefabricated cracks are treated with different high temperatures and different cooling methods and then subjected to uniaxial compression. The T2 spectrum is performed on the concrete that has experienced different high temperatures to detect its pore changes. Acoustic emission is used to monitor the destruction process of the concrete during the test. The composition of the damaged specimen by scanning electron microscope and X-ray diffraction are analyzed, then the relationship between the stress–strain curve, porosity change and macroscopic and microscopic properties of concrete are compared and analyzed. In this study, a certain range of high temperature significantly increased the uniaxial compressive strength of concrete. Then, the uniaxial compressive strength decreased rapidly when the temperature is higher than a certain level. It is observed that the bonding degree of concrete aggregate and cement inside the damaged specimen is different after high temperatures and cooling methods treated by using scanning electron microscope. The damage degree of concrete caused by high temperature and water cooling is far greater than that of air cooling. The acoustic emission signal and energy release between the normal temperature specimen and the specimen after high temperature treatment in the test process are quite different. This paper explains the mechanical phenomena of cracked concrete specimen after being treated with high temperature and different cooling methods from the microscopic and mesoscopic perspectives. [ABSTRACT FROM AUTHOR]

• Bamboo fiber effectively decreases the temperature sensitivity of asphalt mastic. • Bamboo fiber-reinforced asphalt mixture has excellent road performance. • Bamboo fiber delays and controls the occurrence and development of large cracks in the mixture. • Bamboo fiber is a viable alternative to lignin fiber, contributing to sustainable pavements. Bamboo is a plant species that features fast-growing characteristics, and bamboo fiber is a kind of environmentally attractive fiber, which is affordable, recyclable, degradable and renewable. This exploratory study entails laboratory tests conducted to evaluate the potential impact of bamboo fiber on the properties of asphalt mastic and mixture, in comparison to that of lignin fiber. To analyze the road performance and reinforcement mechanism of bamboo fiber asphalt mixture, three kinds of fiber asphalt mastics and mixtures, non-fiber, lignin fiber and bamboo fiber, were prepared. The thermal properties of asphalt mastic and the mechanical properties, high-temperature property, low-temperature property, moisture susceptibility and anti-aging property of asphalt mixtures were tested. Finally, the mechanism of interactions between fiber and mixture was revealed using a scanning electron microscope. Both types of plant fiber can improve the degree of crosslinking between asphalt molecules, thus slightly improving the thermal stability of asphalt mastic at high temperature and effectively decrease its temperature sensitivity. The mechanical properties of lignin fiber asphalt mixture outperformed those of bamboo fiber, while the bamboo fiber asphalt mixture exhibited excellent road performance (especially high-temperature stability, low-temperature crack resistance and moisture stability), notably better than that of lignin fiber. Bamboo fiber can form a close connection with mixture and increase the proportion of structural asphalt in the mixture through adsorption. Both adsorption and mechanical anchoring can reduce the temperature sensitivity and moisture sensitivity of the fiber-reinforced asphalt mixture. The distributed fibers can form a three-dimensional network structure in the asphalt mixture, delaying and controlling the occurrence and development of large cracks in the mixture. Bamboo fiber is a viable substitute for lignin fiber, and its beneficial effects on asphalt mixture might be enhanced in the future by further engineering its surface microstructure and chemistry and improving its dispersion. [ABSTRACT FROM AUTHOR]