Applied Mechanics and Materials Vols. 584-586

Abstract: Asphalt mixture was considered as a two-phase composite, in which coarse aggregates are embedded into asphalt mastic matrix, namely a mix of fine aggregates and asphalt, so that a theoretical framework was proposed to correlate its effective thermal expansion coefficient with its components and microstructures based on the Eshelby equivalent inclusion theory. A four-parameter model with the experimentally determined parameters was used to characterize the viscoelastic constitutive behavior of asphalt mastic. The thermal expansion coefficient prediction of asphalt mixture was conducted and compared with the predictions by the sparse method and the self-consistent method. It was revealed that the prediction from the proposed theoretical framework is reasonable.

Abstract: The microstructure of sea sand concrete wes characterized by the Accelerated Surface Area and Porosimetry System (ASAPS) to detect the concrete micro-prorous structure distribution, the Tabletop Scanning Electron Micro-scope (TSEM) to analysis the sea sand concrete internal microstructure, as well as the X-Ray Diffractometer (XRD) and the Thermal gravimetric/Differemtial Thermal Anylyzer (TG/DTA) to observe the composition of concrete in this paper. The influence on hydration processes of concrete caused by sea sand was reseached from four aspects which are the influences of fly ash on concrete, chlorine salts on sea sand concrete, chlorine salt on fly ash added sea sand concrete and desalination sea sand and not desalination sea sand concrete micro structure features to evaluate the effect of sea sand on regular sea sand concrete and fly ash added sea sand concrete micro structure features and chemical composition.

Abstract: Because ordinary concrete cannot be hardened well under sub-zero temperatures, anti-freeze agents are typically added to prevent the frost damage and to ensure the proper hardening of concrete. With the advantage of a rapid exothermic reaction property, jet set concrete may be used as a cold weather concrete because it can reach the required strength before being damaged by cold weather. Recent studies are reported that magnesia-phosphate cement can be hardened very quickly and hydrated even in low temperature, which can be used as an alternative of severe cold weather concrete in arctic regions. This study developed the magnesia-phosphate cement that can be used in severe cold regions and suggested an appropriate mixture design from the experimental results.

Abstract: Interface bonding is the key technical problems of waste rubber in engineering application. Studies show that, with the increase of unmodified rubber particles dosage, the cement mortar 28 d compressive and flexural strength significantly reduce; when NaOH modified rubber particle content is less than or equal to 5%, it can reduce the compressive flexural strength reduction; The PVA modified rubber particles had no beneficial effect on the strength; rubber particles modified by silane coupling agent KH560, can greatly improve the rubber cement mortar 28 d compressive and flexural strength; the modifier mechanism is studied by scanning electron microscopy (SEM).

Abstract: The aim of this study is to present a model for assessing the dynamic compression behaviour of a micro-concrete. This model is based on the results of numerous tests providing the developments of the mechanical characteristics of the material on a wide range of strain rate from 10^-4s^-1 to 10⁺³s^-1.The Split Hopkinson Pressure Bar (SHPB) dispositive, based on the wave propagation theory in materials, has-been adopted to carry out the dynamic tests on the investigated material. The proposed model is composed of two terms, each characterizing the different contributions noted in the two major explored areas of strain rate.

Abstract: Aiming at the disadvantages of traditional magnetic roasting process, suspension calcining process was suggested to dispose refractory iron ore. The experiment indicated that under the conditions of 750°C~850°C, CO volume percentage was 1%, the limonite and siderite could efficiently transformation into magnetite, which only needed 10~20 secs. Tests of roasting-magnetic separation could attained results as: concentrate iron grade be 49.26%, recovery of iron be 87.28%.

Abstract: The design of tourist souvenir is the structure of the tourism industry needs, is also the important direction of regional economic development. In this paper, aiming at the application of traditional crafts and materials in the three gorges local features, more manifests the design value of the tourist souvenirs. As the modern tourism market the goal of sustainable development, through continuously improve product innovation and research and development mode, to better service to the all-round development of the three gorges tourism market.

Abstract: This article mainly aims at to research the affect of thixotropy on the development of the formwork lateral pressure, the ultimate goal is to minimize the potential safety hazard of construction.Before the experiment, through the tests of net cement slurry, we can determine kaolin (additive) to change the influence of the liquidity of concrete. For the mixture of self-compacting concrete (SCC) ,set different content of admixture. Through experimental simulation measurement in 4 meters height of concrete pouring and pouring diameter of 150 mm, test the size of the lateral pressure casting the bottom template, and compare the condition of not using mineral admixtures, helps to identify the most appropriate for the amount of admixture.

Abstract: This paper chose 5~31.5 mm coarse aggregate (commonly used in highway) to supersede 5~20 mm, 20~40 mm double-graded coarse aggregate (commonly used in airport pavement), studying the influence of 5~31.5 mm coarse aggregate on the airport pavement concrete. The results show that the flexural strength and loss rate of relative dynamic elastic modulus of airport pavement concrete prepared with 5~31.5 mm coarse aggregate meet the airport pavement design requirement, the optimum mix amount is the water-cement ratio of 0.40 and the unit cement consumption of 330 kg/m³, and for frost resistance durability after 200 freeze-thaw cycles, the relative dynamic elastic modulus is still above 90%.

Abstract: Effects of the radius of groove and angle of alloy steel-made cooling slope on the microstructure of hypoeutectic high chromium cast iron after holding at the semisolid state have been investigated. The molten alloy with 1390 °C superheat was poured on the surface of the cooling slope in various radius of groove (100 and 400 mm) and angles (15, 30 and 45°), at constant length and preheating temperature. It was found that cooling slope obviously effects on the microstructure of the alloy. Furthermore, it was also found that the radius of groove and angle of cooling slope affect the size and morphology of the alloy. The results indicate that the minimum grain size of 26μm and maximum shape factor of 0.78 of primary austenite phase was obtained at radius of groove 400 mm and an angle of 30°angle, at a constant pouring temperature, length and preheating temperature.