Applied Mechanics and Materials Vols. 71-78

Abstract: This paper studied on preparation, mechanical and thermal properties of two PCM wallboards made of gypsum and paraffin composite, PCM particles wallboard and PCM bag packed wallboard. Density, flexural and compressive strength and thermal conductivity of PCM particles wallboards deceased as PCM particles dosage increasing. Only PCM particles wallboard with PCM particles dosage 30% is suitable. Thermal comparison between PCM wallboards and pure gypsum wallboard shows that two PCM wallboards have better thermal properties and PCM wallboards can be used in building envelope to cut down building energy-consumption.

Abstract: The basic properties and its influences on mortar properties are studied for the purpose of using recycled fine powder. Results show that mortar water assumption increases and the compressive strength declines with the increase of recycled fine powder content. Efficient ratio of recycled fine powder is propounded for the first time to reflect the contribution of recycled fine powder with different content to mortar strength. It is greater than 1 and thus has certain contribution to mortar strength when recycled fine power content being less than 28%, which reaches the maximum as being 14%.

Abstract: A concrete sulfate corrosion-resistance admixture is developed with anhydrous calcium sulfo aluminate (C-S-A), super fine slag powder (P800) and anhydrite (CaSO₄) in this paper. Scope of prescription is optimized according to performance requirements of JC/T1011-2006. This sulfate corrosion-resistance admixture has declared Chinese national invention patent (201010256189.2)[1]. Corrosion resistance coefficient is tested after sulfate corrosion-resistance admixture is adjoined into fly ash concrete. The results reveal that sulfate resistance of the concrete is obviously improved by addition of sulfate corrosion-resistance admixture, and the its anti sulfate erosion grade is KS150.

Abstract: In this paper, the frost resistance on different water-cement ratio of concrete after the air-entraining agent admixture. When the gas is controlled about 4%, with the lower water-cement ratio, freeze-thaw resistance of concrete is increased significantly. And then the frost resistance of YC20 and YC40 concrete which are mixed in efficient air-entraining water-reducing agent were studied, the experiment results that when the concrete YC40 reached F300, gas content reached more than 4.5%,and the strength without reducing, the durability would improve. But the YC20 is different, so, GL-B4-efficiency air-entraining water-reducing agent does not apply to the water-cement ratio above 0.6 of the concrete

Abstract: The uniform zonal disintegration of surrounding rock is the peculiar phenomena of deep and high stress field, researching the inner mechanism and affecting factors has important meaning for guaranteeing the safety of deep engineering. The paper adopted strain soft Mohr-Coulomb model and carried out numerical simulation of surrounding rock fracture and excavation. The simulation states that along with the unloading time accumulation, the shear belt produced from tunnel wall and developed to inner rock. The corresponding shear stress concentration zone also spread to inner rock and destroy zone increasing. The pore water pressure increasing will accelerate the shear belt developing and increase the destroy degree.

Abstract: Aiming at that general Finite Element Method is difficult to simulate the complex tunnel excavation inducing the second stresses adjusting, the paper proposed the simulation methods combining loading releasing and stress mapping return arithmetic. After the introduction of relative theory, the FEM code has been developed by VC++ . The excavation process of a large section tunnel engineering CRD construction is simulated by the code, the displacements contour, arc top and arc shoulder settlement, horizontal convergence and ground face settlement corresponding to each excavate step have been obtained by the simulation. The regulation of the results are compared with monitoring data, which stated the method is feasible. The simulation has guiding meaning to the tunnel engineering construction.

Abstract: This paper summarizes existing evaluation methods of ground heat exchanger performance. Based on the characteristics of heat transfer in variable flow, comprehensively considering the similarity law of momentum transfer and heat transfer law, the performance of ground heat exchanger was evaluated in winter conditions by a comprehensive heat performance evaluation method – a combination of unit tube length for heat and pumps power consumption.

Abstract: Constructions in Dong inhabit houses respond to the cosmopolitan ecological thought “Man and nature live in harmony” with landscape of simplicity, nature and unity of heaven and humanity. It is not only Chinese nation’s cultural treasure but also a distinguished one in the art of architectural world which forms going through long-term choice and elimination of nature and human society and includes many reasonable ecological construction experience. This paper summarizes its ecological construction experience by researching traditional houses of Dong inhabit villages in Sanjiang, Guangxi to provide guidance for local architectural creation and sustainable development of villages.

Abstract: Experimental results on tensile mechanics properties of GFRP bars at high temperatures are present in this paper. Thirty commercially produced GFRP tensile specimens of 8mm diameter were tested at high temperature ranging from 10°Cup to 500°C. Tensile test result indicates that, the ultimate tensile stress has significant reduction at two temperature zones, one is glass transition temperature of epoxy resin (80-120°C), with strength degradation 22%, the second is the soften temperature of glass fibers(about 400°C), the strength decrease drastically with almost linear rate and remained 33% residual strength at 500°C. The elastic modulus remained unchanged until glass transition temperature of epoxy resin, and the modulus declined linearly with the temperature elevating. Stress-strain relationships of GFRP bars exhibit liner performance even at high temperatures.

Abstract: This paper presents the idea of mixing waste cement mortar into foam concrete block, and gets the foam concrete testing models with the values of dry density at 700 to 1000 kg/m³ , and the compression strength at 0.5-2.5MPa, which are met to foam concrete block standard. At the same time, the power formulas for calculating the dry density and compression strength of concrete cubes doped with waste cement mortar have been brought up, which are coincided with the experiment results well. An initial discussion about microcosmic composition has also been given, which has rather high practical application values since it offers experimental and theory foundations for reusing the waste cement mortar. The innovation significance should not be neglected, since it is the first time doing research on these aspects.