Applied Mechanics and Materials Vols. 174-177

Abstract: Water-reducer is one of the dispensable components in modern concrete, can improve the workability and mechanical performance of concrete, and also has an important influence on the plastic cracking resistance of concrete. In this paper, the flat cracking test was used to evaluate the effect of water reducer on the plastic cracking resistance of concrete, meanwhile, capillary pressure; plastic settlement and evaporation rate were also tested. The results showed that water-reducer could improve the plastic cracking resistance of concrete significantly, and the effectiveness of polycarboxylate water reducer were o better than that of wood calcium and naphthalene water reducer.

Abstract: The glass-covered Co-rich amorphous wires was annealed by an applied stress during the current annealing process. The influence of stress and dc current annealing on the giant magneto-impedance (GMI) effect were investigated by the magneto-impedance. Our experiments showed that the magentic anisotropy is reduced by the annealing treatments, furthermore, the maximum GMI value is increased to 105 %.The GMI value is enhanced by increasing the outer domain volume and inducing a transverse anisotropy due to the changing of inner stress.

Abstract: Low, medium and high variability of aggregates of concrete were designed and prepared and the influence of variability of recycled aggregates on the mechanical properties and durability of concretes was investigated. The experimental results indicated that the kinds of strengths, static compressive elastic modulus and durability of recycled concrete were decreased at engineering-acceptable level compared with natural aggregate concrete; the most properties of recycled concrete with high variability of recycled aggregates are not very different from that of recycled concrete with medium variability of recycled aggregates even that of natural aggregate concretes; however, the variability of properties of recycled concrete with high variability of recycled aggregates are much different from that of medium variability of recycled aggregates and more different from that of natural aggregate concretes, which means if only one or limited properties of recycled concrete were tested, the existing high variability of properties of concrete may not be revealed to a full enough extent, and the possible neglect of this high variability may result in potential engineering risk in application of high variability of recycled aggregate; the content of hardened cement paste and mortar attached to the recycled aggregate is found to be the essential factor to influence the properties of recycled concrete.

Abstract: Wall thermal insulation is one of the most effective ways for building energy-saving. Selecting suitable thermal insulation materials is important to energy-saving, economy, safety and durability, etc. The principle of fuzzy matter-element method is introduced as well as entropy method. The methods are use to evaluation wall thermal insulation materials to determine the most appropriate material. The performance indicators of wall thermal insulation materials are analyzed. An application case is studied using the methods, and Extruded Polystyrene (XPS) is selected to be the most suitable material.

Abstract: Influence on activation property of coal gangue by calcining temperature was discussed. The experimental results show that C₁₂A₇ and C₂S with hydraulic-activity are created in coal gangue calcined at 900 - 950°C which has reasonable pore distribution after hydrating.

Abstract: In order to enhance the strength of cold drawn high carbon steel and improve its comprehensive properties ,the law of change in microstructures and properties of high carbon steel with various contents of V and N were investigated .The size of pearlite colony，interlamellar spacing of pearlite and mechanical properties with various contents of V and N were measured; the change of magnetic properties of wires with different cold drawing strains were measured by VSM. It is shown that V can decrease the size of pearlite colony and interlamellar spacing of pearlite when V content is less than 0.06 wt %; N can decrease the size of pearlite colony and increase slightly the interlamellar spacing of pearlite. The tensile strength is enhanced with increasing V or N content, but V decrease plasticity of wire and N has little effect on it. The cementite in wire is dissolved with increasing cold drawing strain. The volume fraction of cementite is decreased to 4.4%，dissolution of 7.8%，as the true strain is increased up to 3.19.

Abstract: N-compound coating based Fe has the feature of effective, rapid and large depth. So it is fit for repairing the metal parts. FeCl2 plating liquid fixed with n- Al2O3 was adopted, in term of given technical process, so the coating can be acquired. Used the coating, glide, rolling, fixed, half fixed friction and frictional pairs tribological characteristics were studied. The conclusion is that under the condition of gliding and half fixed, the bearing capability is very well, breaking in was necessary when the frictional pairs needed to work.

Abstract: The micro/nano fibrils was used to modify the soybean glue, which was used as the adhesive of poplar plywood. The poplar plywood bond strength were evaluated. To explain the improvement in mechanism, Differential Scanning Calorimetry(DSC) and Dynamic Mechanical Analysis apparatus(DMA) were applied to analyze the influence of poplar macro/nano fibrils on soybean glue. The test of bonding strength results show that the bond strength of poplar plywood was enhanced as micro/nano poplar fibrils was added. And the DMA figures of soybean glue illustrate that poplar macro/nano fibrils has improved the deformation resistence of soybean glue plywood and the heat resistance of soybean glue.

Abstract: The cavity wall material is a kind of new saving energy and environmental protection building material having good physical and mechanic performance including lightweight, high strength, heat insulation and thermal insulation. Making full use of good physical and mechanic performance, as the infilling wall of steel frame structure, a new cavity composite masonry wall material is put forward, which can bear lateral load with steel frame together. Based on test of two specimens, the failure process and pattern is analyzed in detail in this paper, and the hysteretic behavior, energy dissipation and stiffness degeneration under the seismic force. Comparing with the steel frame, the cavity composite masonry infilling wall steel frame structure has higher strength, light weigh, higher stiffness, good anti-seismic behavior and ductility. The conclusion is reference for the seismic design of the infilling wall steel structure.

Abstract: The influence of anhydrite on mechanical property and alkalinity of sulphoaluminate cement clinker was investigated. The alkalinity was examined by mixing powdered samples with a solvent and measuring the pH of the suspension. The hydration mechanism was analysed by XRD analysis. The results indicated that with the increase of anhydrite addition, both the alkalinity and compressive strength decreased. Yeelimite completely converted into ettringite with the dosage of anhydrite reaching to 50% by weight of the paste. With the dosage of 30%, the 7 d pH could be reduced to 10.43 while the 7 d compressive strength was 48 MPa.