Advanced Materials Research Vols. 335-336

Abstract: The thermal insulating of new and existing buildings is of a key influence in reduction of their energetic demand factor resulting in reduction of emissions of gases, carbon particles and dust which directly improves the environment. At development of light thermal insulation plasters with very low thermal conductivity the foam-plastic matters or light porous aggregates are frequently used at present. The foam-plastic materials do not appear as convenient ones in view of the environment and sustainable development as well. In the given case the thermal insulation plasters based on light cellular aggregates appear as more suitable. However a majority of light aggregates (for example expanded perlite) do not show a good ratio of insulation and mechanical properties. The paper describes a design and development of thermal insulation plasters based on expanded obsidian that can be used for thermal insulating of building constructions and for moisture sanitation. Considering the applied type of aggregates the materials show better ratio of thermal insulation and mechanical properties while in practice the plasters can be used as a full- value alternative for classical thermal insulation systems.

Abstract: This paper presents studies of prediction of compressive strength of lightweight aggregate concrete (LWAC). In order to choose the optimized prediction model, the prediction models based on different parameters, which included compressive strength of mortar matrix, volume content of lightweight aggregate (LWA), crushing strength of LWA, particle density of LWA and shape index of LWA, were analyzed and compared. For LWAC, due to the effect of LWA on LWAC is more obvious than the effect of mortar matrix, therefore, a prediction model that just used LWA properties to serve as parameters of prediction model can predict LWAC strength. The LWA properties included volume content, crushing strength, particle density and shape index. As long as the LWA properties are known, the advantage of the model is that LWAC strength can be predicted. The best prediction discrepancy of 12.9% compared with the experimental results.

Abstract: With considering the effect of the initial pore water pressure and the variety of seismic pore water pressure generation, a two-dimensional inhomogeneous compound diffusion equation for describing generation and dissipation of seismic pore water pressure are given by coupling the Terzaghi’s consolidation theory and the increasing mode of seismic pore water pressure in saturated sands. The analytical expression of the diffusion equation is obtained by using the method of the generalized Green function and the finite Fourier transformation.

Abstract: In concrete construction, it is usual to encounter integrating problems between old and new concrete interfaces, such as disease concrete’s repairing and anchoring, concrete blocking construction and etc. Due to low cohesion strength between old and new concrete interfaces, weak interface is formed, then old and new concrete cannot construct as an integrate whole which tends to be damaged along the interfaces after being loaded and results in hidden danger. Regarding of this situation, the paper optimizes the mix on the base of mixes tests on inorganic cohesion material used between old and new concrete interfaces. When the material is used to old and new mortar interfaces and old and new concrete interfaces, cohesion tensile strength in interfaces equates or is higher than that of mortar itself and concrete itself; In the mean time, through permeability test the impermeability in the interface equates that of concrete itself, eliminating weak interfaces between old and new concrete. Physical property tests show that the material’s mechanical property is better than that of concrete, deformation property is close to concrete’s, especially linear expansion (temperature deformation) coefficient is basically consistent with that of concrete, avoiding peel-off damage after repeated internal forces due to too much difference between linear expansion coefficients when organic cohesion material is used. By analysis of hydraulic productions in interfaces and micro structure, the mechanism of inorganic cohesion glue is illuminated. It results in satisfying cohesive effect when optimized inorganic cohesion material is applied to high-strength concrete repair and RCC interfaces.

Abstract: By the experimental research to the effect sucrose-natural gypsum as composite retarder on the performance of cement and concrete. This paper analyzes and summarizes the fact that the influence of this kind of composite retarder is more obvious than the slow setting effect of a single sugar or plaster. And the retardation of cement and concrete the mixing time is basically the amount of sugar a positive correlation. And on the other hand, it will not influence other physical properties.

Abstract: Material adsorption process is the reverse process of evaporation diffusion, reflecting directly the wetting degree of material, is one of the main factors of material drying shrinkage. Based on pore structure theory, this article designed a device measuring the wetting properties of materials, tested different recycled aggregate replacement rate recycled aggregate concrete isothermal absorption curve. The article proposes the water contact angle can be calculated from the initial absorption curve, and analyzes its impact on drying shrinkage of recycled aggregate concrete.

Abstract: Comparson research as to the relationship between building residues solidified by cement and those solidified by soil stabilizer are made , and the unconfined compressive strength of them increased over time are analyzed in the paper. When the soil stabilizer is mixed with the building residues, the acicular ettringites acting as inlay or infilling are formed in the solidified body. This is the reason why their unconfined compressive strength are increased. Some relevances show that the more the acicular ettringite was formed, the higher the confined compressive strength of the solidified bodies would be, and vice versa.

Abstract: A new concrete filled steel tube (CFT) frame structure was developed by using self-compacting concrete (SCC). Experimental work was done in order to investigate seismic behavior of the new CFT frame structure. The experiment result shows that sufficient deformation capacity is able to be obtained in PC bar jointed CFT column-beam joint specimens. Cost estimation and comparison result of the new CFT frame structure and steel frame structure system were also be described.

Abstract: Light and thin bipolar plates are essential in increasing the power density of a fuel cell. To construct high-aspect-ratio micro flow channels in such plates is, however, a big challenge. This study reports on machining micro flow channels in metallic bipolar plates using micro electrical discharge machining milling (micro EDMM) with a tungsten carbide electrode. We successfully machined metallic bipolar plates with 500μm channel and rib widths, height of 600μm in a reaction area of 20mm × 20mm, on 1mm thick of SUS316L stainless steel. The optimal operating parameters were explored and discussed. The performance of resulting fuel cell (Metallic-FC) was compared with a commercial available fuel cell composed of graphite bipolar plates (Graphite-FC). The high temperature of Metallic-FC increases its electrochemical reaction rate and consequently yields higher power density (723 mWcm^-2) then that of Graphite-FC (687.3 mWcm^-2)

Abstract: The influence of the strain of AlN buffer layers on the strain evolution of GaN epilayers grown on 3-in 6H-SiC substrates by metal-organic chemical vapor deposition was investigated by double-crystal X-ray diffractometry, and Raman scattering spectra. It was found that the tensile strain of the GaN epilayers mainly decreases with the strain of the AlN buffer layers varied from tensile to compressive. A model based on the strain evolution during the epitaxial growth is proposed to provide a valuable reference for the massive production of large scale and high quality GaN epilayers.