Applied Mechanics and Materials Vols. 99-100

Abstract: As the British has a cold and rainy climate, which is variability, its relatively high energy efficiency standards has been set up. Energy efficient building in the United Kingdom in the technical measures three main areas: 1) use of structural measures to raise the walls, roof and windows of the thermal insulation properties; 2) the use of solar energy; 3) improving the heating system. Currently the United Kingdom to promote passive solar house without external mechanical action, heat-absorbing insulation materials of construction for the media, the use of natural cold and hot air exchange, to the use of solar energy.

Abstract: In this dissertation, the mathematical models of thermal conduction procedure and thermal deformation for an insulated composite wall are established. That thermal conduction model takes complicately environmental changes (such as solar radiation, building self-radiation, reflecting ground radiation, air temperature, outdoor heat convection and indoor heat convection) into account. The thermal conduction problem is solved using finite difference method on spatial domain and DIPIM on time domain respectively. Computational formulae of thermal stress are deduced based on theory of thermal elasticity and plane section assumption. Finally, both the hourly temperature field and the thermal stress for an exteriorly and an interiorly insulated composite wall within a typical day of winter and summer are analyzed. Computational results show although the exterior insulation system is more beneficial to the stability of primary wall than interior one, the effect of environmental changes on mortar cracking and decorative materials inside the exteriorly insulated system than that inside the interiorly insulated system. The temperature gradient inside the insulated lamination is bigger than that in other laminations for any insulated system within whether winter or summer. In addition, the temperature gradient inside the insulated lamination for the interiorly insulated system within winter is bigger than that within summer, but the temperature gradient inside the insulated lamination for the interiorly insulated system within summer is bigger than that within winter. Although the exteriorly insulated system is more beneficial to the stability of primary wall than the interiorly insulated, the effect of environmental changes on mortar cracking and decorative materials for the exteriorly insulated system is bigger than that for the interiorly insulated. An exteriorly insulated system is more beneficial to the primary wall than an interiorly insulated system according to environmental attacks on the primary wall.

Abstract: The paper briefly introduces the form and construction method of a new reinforced concrete composite wall (RCCW) with inner insulating layer of polystyrene panel. The thermal insulation properties such as heat resistance, heat exchange resistance and heat transfer coefficient of the RCCW were measured by the protection chest method, six specimens in dimensions of 1450mm×1450mm×300mm were cast with the same thickness of prototype walls of building envelop, three kinds of linkages of the RCCW were considered, and two surfaces of the specimen were tested respectively as the heat bearing surface to simulated different heat resources. Based on the tests, the effects of linkages and heat resources on thermal insulation properties of the RCCW are analyzed, some improvements are proposed for reducing the heat-bridge effects as much as possible.

Abstract: Briefly outlines current situation of building energy consumption in China. On this basis, lists the efficiency measures of building energy conservation: including energy optimization in building design process, new technologies in building envelope, energy saving of heating system, heat pumps, large public buildings energy conservation, efficient lights and energy saving electrical appliances.

Abstract: In order to research the crack initiation and propagation behavior in rock mass under coupled static and dynamic loads, the crack initiation angle and expansion angle formulas are set up by use of the fracture mechanics theory, then numerical simulation of crack propagation are conducted using software RFPA. The results show that: the crack always extend toward the dynamic stress direction; the bigger of the crack dip, the smaller of the crack initiation angle and the more difficulty of the crack initiation and propagation, meanwhile the less influence to the damage of rock. What’s more, when the crack dip is small, theoretical value and numerical simulation value of initiation angle will be have good uniformity.

Abstract: The influence of wollastonite or plant fiber on the property of autoclaved cement concrete is studied by chemical composition analysis, X-ray diffraction analysis, scanning electron microscopy and energy spectrum analysis. The results showed that the two fibers were benefit to bending strength of autoclaved cement concrete. The suitable content of wollastonite was about 15% of cement mass, and the increased amplitude of flexural strength was more than 30% and the compressive strength slightly increased for autoclaved cement concrete admixed wollastonite. The optimal content of plant fiber was about 1.5% of cement mass, the increased amplitude of the flexural strength was more than 20%, and the compressive strength change of autoclaved cement concrete was not significant for autoclaved cement concrete admixed plant fiber.

Abstract: The paper using different strength cement mixture of cement paste, cement mortar and cement concrete, to which adding single plasticizer and two kinds of mixed with plasticizer, Experimental study plasticizer on different cement adaptability, effects of mixture of different water-reducing admixtures, Submit Issues to be noticed on plasticizer storage and use.

Abstract: A series of mineral admixture slurry with different fineness was manufactured by means of wet-milling with stirring mill. The effect of mineral admixture treated by dry milling and wet milling on chemical corrosion resistance of concrete in artificial seawater was investigated in this paper. Results showed that, the chemical corrosion resistance of concrete with fly ash and original fly ash treated by different grinding mode is improved, and the chemical corrosion resistance of concrete with slag is relatively inferior. The compound of fly ash and slag can evidently improve the weakness of slag concrete that has poor chemical resistance.

Abstract: CaCO₃ whiskers were incorporated into the cement mortar in this study and the effects of whiskers on the impact resistance of mortar were investigated. The results showed that CaCO₃ whiskers could improve the impact resistance of cement mortar before initial cracking. When the whisker content was 10%, the reinforcing effect was optimal. But after initial cracking, the capacity of matrix to resist further impact load was not improved significantly. By observing the failure modes of specimens, it was shown that the crack branches of whisker-reinforced cement mortar were increased, which indicated the brittleness of matrix was decreased and the toughness was improved to some extent. In addition, the reinforcing mechanisms of CaCO₃ whiskers in the cement mortar were also discussed

Abstract: This study used Type I Portland cement with Na2Oeq of 0.67% to fabricate a mortar specimen with w/c ratio of 0.5 and a dimension of φ10  3 cm. The 7 volume fractions of aggregate (Vf) were adjusted to 0, 10, 20, 30, 40, 50 and 60%, and Acceleration Lithium Migration Technique (ALMT) experiments with 9 A/m2 constant current density were performed. The results show that for specimen with Vf of 10%, the negative effects on ion migration generated by aggregate dilution and tortuosity effects were the greatest; therefore, the removal times of Na + and K+, the time it took for Li+ to pass through the specimen and the time for Li+ to reach steady state were all longer than in the other experiments. When Vf was increased to 20 and 30%, the negative effect from the dilution and the tortuosity effects generated by the increase in Vf was cancelled the positive effect from ITZ on ion migration. When Vf was increased to over 30%, the percolation effect from ITZ controlled the behavior of ion migration. During the ALMT experiment, the anode steadily produced a large amount of O2, while the cathode produced a small amount of H2.