Applied Mechanics and Materials Vols. 174-177

Abstract: In view of the new concerns in deepwater cementing, such as low temperature, shallow water/gas flow and so on, that can not be efficiently solved with conventional cement systems, a new SP-D cement with calcium sulphoaluminate and silicate was developed to adapt to deepwater low-temperature cementing. Test results show that the SP-D cement possesses high early-strength under low-temperature, favorable compatibility with conventional accelerators and retarders, and can be used to prepare the low density cement slurries combining with microsphere. The research offers a new SP-D cement for deepwater cementing with favorable high early-strength, improved migration control ability and minute expansion of set cement, and also shows prospective solution for the confronted problems in deepwater cementing.

Abstract: Non-biodegradable rubber waste from tyres can be employed for the making of pseudo-ductile cementitious composites (PDCC) which requires a matrix of low toughness. In the present study, compressive strength and fracture toughness are measured for cementitious mortar containing small volume of sand, and with or without rubber particles. Also micro-hardness testing, mercury intrusion porosimetry and scanning electron microscopy are performed. According to the test results, the incorporation of 10%~11% rubber particles with average size of 0.4mm or 0.2mm by volume decreases the compressive strength by 40%~60% and the fracture toughness by 10%~40% which makes preparation of PDCC easier. These can be explained by the presence of cracks at the interface between rubber particle and matrix, as well as the increased porosity and specifically the increased content of large capillary pores in the cementitious composites with rubber particles which is considered as solid air-entraining agent. Moreover, there is a more significant increase in the content of capillary pores for composites with small size rubber particles, explaining the lower strength and toughness when these particles are employed.

Abstract: By testing the Axial compression performance of the Block of concrete short columns regenerated by No rib and steel ribbed thin-walled square and simulating the finite element program ANSYS calculation ,we are going to reveal the square steel tube regeneration block of mixed component axial compressive deformation and failure mode ,and analyze the longitudinal force and the strain relationship of the longitudinal direction and the horizontal direction as well as the effect on forcing performance and failure mode of specimen played by the combined concrete force of fresh concrete. The results showed that the main failure mode of specimen is crushed drum-type damage. In the elastic state, all the strain growth in the middle section and the corner is self and growth of longitudinal strain of the two is relatively consistent. On damaging stage, the specimen without ribs is softened, while the specimen with ribs shows a feature of stiffening. The results of finite element analysis fit the test results well.

Abstract: Hydrogen is considered a promising alternative energy carrier that can potentially facilitate the transition from fossil fuels to sources of clean energy because of its prominent advantages such as high energy density, great variety of potential sources, light weight and low environmental impact (water is the sole combustion product). Due to low price and abundance magnesium should be considered as a potential candidate for hydrogen storage. Recent progress in the application of Magnesium-based nanostructured and composite materials in hydrogen storage is presented in this review. The main focus is on the synthesis of composite material, the design of nanocomposite material, the improvement of the thermodynamical properties and kinetics of hydrogenation/dehydrogenation and the improvement of resistance towards oxygen contamination.

Abstract: The effects of rare earth metals on the inclusions and the mechanical properties of 2Cr13 stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of inclusions in 2Cr13 stainless steel are changed, and rare earth metals played a very good role of modifying inclusions. The fracture mode of 2Cr13 stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding Ce into the steel, and the spherical inclusions of rare earth oxysulfide in the dimple are the main factors for this transformation. The transverse impact toughness of 2Cr13 stainless steel is improved obviously by Ce. In comparison with 2Cr13 stainless steel without Ce, the transverse impact toughness of 2Cr13 stainless steel with Ce is increased 54.55% at -40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 11.90%, 16.67 respectively.

Abstract: The special physical characteristic of diatomite was described in the paper. The point and superiority of the diatomite for application in coating and high-performance concrete were also discussed and it will have broad prospects application in the future.

Abstract: Using antifreeze compound in negative temperature concrete construction can not only reduce the liquid freezing point of the concrete, promote coagulation and achieve the water-reducing effects, but also improve the early strength of the concrete. Through the concrete test, the antifreeze compounded basically with the acrylic polycarboxylate super plasticizer (acrylic acid series for short) can achieve good liquidity and fluidity, low slump loss, early strength enhancements in particular the great potential to enhance early strength and many other performance characteristics.

Abstract: For the disadvantages of the traditional NDT methods for coating defects, Thermal Wave Nondestructive Testing (TWNDT) technology was used to detect coating debonding defect on composite Materials matrix. Numerical simulation method was used to simulate the heat transfer process of thermal wave in the coating material with defects. The factors influencing the testing sensitivity were in-depth studied, including the debonding defect size and coating thickness. Simulation results show that: TWNDT technology can quickly and efficiently identify the size of the coating debonding defects, while the thickness of the coating is an important factor influencing the inspection sensitivity for the thermal wave detection.

Abstract: With the deep reform of national policy of building energy conservation and the increasing requirements of building fire protection, building insulation industry appeared a hitherto unknown development opportunity and challenge. This paper introduces the research and application of phenolic foam plate, modified phenolic foam plate with thermal insulation, fire prevention, environmental protection and other excellent properties, puts forward in the field of building energy conservation should be vigorously promoted the application of phenolic foam.

Abstract: Materials for exterior wall external insulation have various types and the uneven development in different areas. Based on the studies of related works, exterior wall external insulation can be generalized as four series according to the construction technologies, which includes the series of the plug-in insulation materials, the slurry and spray, the concrete sandwich heat insulation, and the energy-saving inorganic insulation materials. Associated with China’s situation, the application features and developmental prospect of main exterior wall external insulation materials in every series have been emphasized, and furthermore, several suggestions have been given to the development of exterior wall external insulation materials in China.