Applied Mechanics and Materials Vols. 253-255

Abstract: This essay introduced that shape memory alloy in martensite-austenite coexisting was use to control the structural vibration. The proportion of martensite and austenite in shape memory alloy was selected which could realize the two basic characteristics of shape memory alloy. Based on Liang model, the mechanical model of shape memory alloy was established. The computer simulation analysis of the structure was achieved by using Matlab, and the result of numerical analysis proved that shape memory alloy in martensite-austenite coexisting could effect structural vibration control.

Abstract: The researchers studied the effects of air-entraining agent, water reducing agent, water-retentive and thickening admixture on the performance of building mortar, and the air content, coursing degree, and mortar strength, which helped improve the peaceability and durability of the mortar.

Abstract: The crack resistance of concrete with crushed basalt aggregate was studied. Compared with the limestone concrete, the basalt concrete has larger drying shrinkage and autogenous volume deformation. The linear expansion coefficient of basalt concrete is 1.3×10－6 /°C larger than that of limestone concrete, and it has additional temperature deformation of 24.1×10－6. According to the analysis on temperature-stress of concrete, the cracking temperature of basalt concrete is 8.9°C higher than that of limestone concrete, and the crack resistance of basalt concrete is unfavorable.

Abstract: Basalt fiber was added to the traditional cement-based materials to improve the physical and mechanical properties. The mixture ratio of the matrix, the basalt fiber content, and the super-plasticizer type as well as its contents were designed optimally. The fluidity test, axial compressive strength and cube compressive strength test, flexure strength test were carried out. The results show that the fluidity and the compressive strength of basalt fiber reinforced cementitious composite(BFRCC for short) reduces when the basalt fiber content increases, but the toughness of traditional cement-based materials is improved by adding basalt fiber.

Abstract: Although various models exist for envelope curves of concrete confined by transverse reinforcement, only a few simple models represent the hysteretic behavior of the confined concrete; therefore, development of stress–strain model of unloading and reloading paths for confined concrete is needed. In this paper, an experimental and numerical investigation for describing the cyclic stress–strain behavior of lateral ties confined and polyolefin fibre reinforced concrete (CPFRC) prisms under repeated axial compressive loading is presented. The study focuses on the effect of repeated unloading and reloading cycles on confined concrete prisms. The combined effect of spacing of lateral ties and volume fraction of polyolefin fibres was studied both experimentally and numerically from the point of deformability characteristics of concrete under repeated loading as loading, unloading and reloading.The envelope curve is derived from the results of uniaxial, monotonic, compression loading tests specimens. It explicitly accounts for the effects of lateral tie spacing of 145mm spacing and 75mm spacing and polyolefin fibres of volume fractions 0.7% and 1.2% on concrete prisms of size 150 ×150 ×300 mm were investigated. The behaviour is implemented in the finite element program in ANSYS software, with a view to analyzing CPFRC prisms under repeated loading. This analysis accounts for energy dissipation through hysteretic behavior, stiffness degradation as damage progresses, and degree of confinement. It was observed from hysteretic behavior that for increased polyolefin fibres volume fractions the degradation of strength and stiffness reduces significantly.

Abstract: Modifying crystal morphology was the key technology of the preparation of α-calcium sulfate hemihydrate from flue gas desulphurization gypsum using the hydrothermal method under atmospheric pressure. For exploring crystal modifier, the crystal morphology of α-calcium sulfate hemihydrate in preparation from flue gas desulphurization gypsum with various organic diacid was studied, by polarizing microscope profile observation. The results showed, When the space between two carboxyls was triplicate length of C-C, the organic diacid had the best effect of modifying crystal morphology.

Abstract: Today, efforts are underway in a number of areas to conserve the environment and protect natural resource. In the construction industry, many researchers have studied the development of new concrete using recycled aggregate (RA). This research proposes a multiple regression model (MRM) for predicting the compressive strength of recycled aggregate concrete (RAC). The compressive strength data of 85 specimens of RAC strengths were used for constructing and evaluating the prediction model. The average error rate of the constructed MRM evaluation is 7.18 percent. This result will be useful for predicting the compressive strength of RAC using multiple regression analysis.

Abstract: Recycled Aggregate Concrete (RAC) is referred to as Recycled Concrete (RC). In this paper, the compression performance of recycled concrete was researched using the micromechanics. The recycled concrete was taken as a five-phase composite material consisting of recycled coarse aggregate, old hardened cement paste, new hardened cement paste, the old interfacial transition zone (Old ITZ) and the new interfacial transition zone (New ITZ) on meso-level. A random aggregate model was used to simulate the meso-structure of recycled concrete. The propagation process of cracks and the mechanical properties of uniaxial compression specimens of recycled concrete were simulated using finite element method (FEM) with damage model. The numerical simulation results agree well with the corresponding experimental results. The results show that the specimen usually damaged along the old interfacial transition zone and the new interfacial transition zone.

Abstract: Papers removed due to plagiarism. The original was published by http://www.sciencedirect.com/science/article/pii/S0008884610002796

Abstract: This paper investigated the effect of fly-ash on environmental sustainability and engineering performance of mortar. Samples of mortar were prepared with different dosage of superplasticizer to gives three ranges of workability that is normal slump flow, high slump flow and self-compacting flow. Cement content of 550 kg/m³, water/binder ratio of 0.35, binder/cement ratio of 2.00 and fly ash replacement 10%,20%, 40%, and 60% were adopted for the mix proportion.The relationship to look into are the potential of CO2 reduction in the mortar mixes while cement content were replace by fly ash. Results showed that self-compacting mixes with 20 % replacement by fly ash provides an increase in 28 day strength, enhancing the durability with low % of water absorption and reducing the environmental impact with low CO2 footprint. This gives it the best balance of durability and environmental sustainability impact of the mixes.