Advanced Materials Research Vols. 652-654

Abstract: Due to excellent mechanical properties and high working efficiency, FRP sheet has attracted significant attention from the field of strengthening in civil engineering. This paper summarizes the current achievements in the FRP strengthened reinforced concrete beams under fatigue loading. The review and discussion focuses on the development of fatigue design, the fatigue failure mechanism, reinforcement methods,and environmental effects. Finally, it puts forward the main research directions in this field in the future.

Abstract: The paper study on the properties of Tricalcium Silicate (C₃S) in different physical and chemical environment, the results suggest that neither chemically nor by way of adsorption and that the physically bound water could not act as a solvent for the ethanolamine. Small-angle neutron scattering studies allow a nondestructive description of statistically representative microstructures in the scale range from micrometer to nanometer. Moreover, the scattering signals can be analyzed in a variety of ways, and more detailed insight can be provided into the very complex cement paste microstructure.

Abstract: Velocity gradient and low efficiency zone exist in the common forced mixing. The linear velocity of mixing is low, and the mixing time is long. The concrete has poor micro uniformity. The interface bonded strength and the durability are low. Based on the deficiency of common forced mixing, we put forward vibrating mixing technology and have successfully developed a device. The device adopts the method of forced mixing and vibrating mixing combined, which makes the material particle own certain vibrating frequency and present in vibrating status not only to destroy the sticky connection of mixture, but also reduce friction in materials to promote materials from clusters into uniform distribution. Meanwhile, the device improves micro uniformity and interface connection strength of concrete, and air content of concrete can reach above 3%. The mixing time is shorter and the cement dosage is fewer under the condition of invariable concrete strength.

Abstract: The macroscopic performance of three kinds asphalt and its after aging were analyzed, and aging mechanism and characteristics were explored by. FT-IR.The results showed that the asphalt dynamic shear G*/sinδis very consistent with penetration ratio, moving wavenumber of carbonyl is a valid indicator for the evaluation of asphalt anti-aging ability.

Abstract: Previous studies found that there were some problems when processing goaf by filling method, such as large amount of cement, and high cost. A new type of cementing material was investigated in this study. Its main ingredients was graining blast furnace slag. on the chemical activation, its activities were substantially improved, and the technical parameters of the filling body were markedly ameliorated. Furthermore, the new cementing material complied with the filling cementing material standard of China. The results demonstrated that the new type of cementing material which overcome some traditional shortconmings could be the pottential material for the similar mines which exploit ores by back-filling method.

Abstract: The effects of natural and artificial weathering on mechanical properties of Chlorinated Polyvinyl Chloride (CPVC) pipe material are investigated. Tensile specimens, prepared from locally manufactured CPVC commercial pipes (4-in Schedule 80) were exposed for periods ranging from 2 weeks to 18 months in the harsh weather conditions of Dhahran, Saudi Arabia. The accelerated artificial weathering was carried out in the Q- Sun Xe-3-HS Xenon Test Chambers for periods ranging from 100 to 3000 hours. Standard tensile tests were performed before and after exposure. The tensile test results show that natural and accelerated artificial weathering had limited effects on the tensile and fracture strengths and modulus of elasticity of the material. However, the deterioration of the fracture strain is noticeable for exposure periods as short as 15 days of natural exposure and 100 hours of artificial UV exposure. Visual analysis of exposed specimens revealed that both types of exposures resulted in the discoloration of the specimens.

Abstract: In order to investigate the effect of moisture content on thermal physical properties and heat transfer of plywood during hot pressing, the quasi steady method was applied to measure the thermal conductivity, specific heat and thermal diffusivity values of the resinated plywood assembly with a UF loading rate of 300g/m2 under different moisture conditions. Results showed that with the increase of moisture content in a range of 10-22%, the thermal conductivity and specific heat of the plywood assembly enhanced significantly, and that plywood hot pressing noticeably consisted of fast heating and slow heating phases: during the first phase the heating rate of the core ply was quickened with the increase of moisture content while the second phase did not show any significant impact of moisture content on the corresponding heating rate.

Abstract: Withdrawn at authors request

Abstract: With higher cleanness upgraded steadily, surface failure of metallic materials in very high cycle fatigue (VHCF) regime beyond 107 cycles has been reported one after another. The occurrence of surface crack initiation to failure in VHCF regime is closely related to the following factors: (i) surface finishing condition of specimen, i.e. whether some grinding scratches, grooves and cavities with a relatively larger size than the subsurface defect exist at the surface of specimen; (ii) type, size, location, distribution and density of metallurgical defects such as inclusion contained in the subsurface of material; (iii) degree of persistent slip band (PSB) deformation induced by surface roughening of specimen, mainly corresponding to the some ductile single-phase metallic materials. Furthermore, the effect of environment such as humidity also accelerates surface crack initiation and propagation in VHCF regime. In the present paper, the authors briefly reviewed surface failure modes of metallic materials in VHCF regime beyond 107 cycles, and analyzed the surface crack initiation and propagation mechanisms from the viewpoints of the fracture mechanics and statistics.

Abstract: The X-ray diffraction method (iXRD) has been applied into the measurement of residual stress ultrasonic impact ultrasound before and after the impact test process residual stress of aluminum alloy welded joints. Research different inrush current, different impact time of different ultrasonic impact of the process on the residual stress of welded joints of aluminum alloy welded joints welding residual stress distribution and its variation. We can study the distributing status and disciplinarian, and testify the step to adjust the welding residual stress by ultrasonic impact treatment. The research supplys the data supports for welding residual stress engineering disposal and weld joint assistant consolidation to improve abilities against the gatigue. The research shows appropriate welding and ultrasonic impact treatment technics can effectively adjust welding residual stress and meet the RAMS demands about the product.