Advanced Materials Research Vols. 250-253

Abstract: Based on compression curves of spherical pores Al foam measured, compressive yield strength, the densification starting pointand energy absorption had been investigated. The compressive stress-strain curve of spherical pores Al foam consists of three distinct regions, i.e., the linear elasticity region, yield platform stage and the densification region. The way to determine the densification starting pointε_D of high density metal foam has been presented. Spherical pores Al foam is a cellular metal material of high plastic performance, so energy absorption capability of it is bigger than that of spherical pores Al alloy foam. Compressive yield stress was in good agreement with Gibson-Ashby model’s expectation．

Abstract: Using high pure magnesia and magnesia-spinel as the main raw material, keeping the same quantity of spinel, specimens were made with different spinel size distribution (≤0.044mm, 1-0mm, 2-1mm, 3-2mm and 3-1mm). Dextrin and brine are the binder. Specimens were dried at the temperature of 110°C for 24 hours, sintered at the temperature of 1680°C holding 8 hours in a tunnel kiln. The properties and microstructure of the specimens were analyzed. The results are shown that the addition of spinel with grain size of 3-1mm improves sintering of magnesia-spinel brick, with the thermal shock resistance reaching 18 cycles, the cold crushing strength reaching 54 MPa, improving the comprehensive performance of the magnesia-spinel brick.

Abstract: Four groups of specimens were made from Magnesia and alumina-zirconia synthetic materials, the content of alumina-zirconia synthetic materials was 5%, 10%, 15% and 20% respectively. While one group of reference specimen was made from magnesia and magnesia-alumina spinel at the same conditions for comparing. The Ligno-sulfite was used as binder. The raw materials were mixed homogeneously and then were molded to 5 groups of specimens. After being dried at the temperature 100°C holding 24 hours, the bricks were sintered at the temperature 1530°C 10h, and then the physical performances of the specimens were tested. Phase composition and microstructure of the specimens were also analyzed. The result shows that the performances of the MgO- Al₂O₃-ZrO₂ specimens are better than that of MgO-Al₂O₃ specimen. The specimen which contains 10% alumina-zirconia synthetic materials has the best comprehensive performance. The thermal shock resistance and erosion resistance of the MgO-Al₂O₃-ZrO₂ specimens are better than the MgO-Al₂O₃ specimen. It proves that MgO-Al₂O₃-ZrO₂ bricks are potential good material for sintering zone.

Abstract: The compactness and water impermeability of the concrete mixed with magnetized water in different degrees are studied in the thesis. According to the principle of cross-test, 21 samples with the intensity levels C20, C25 and C30 are chosen in the impermeability test. The test indicates the difference of impermeability between magnetized water concrete and ordinary water concrete at the condition of same strength to study the special law influenced by the flow speed of water and the magnetic field strength. The best magnetic field strength and the best water flow speed have been obtained among the range of test parameters.

Abstract: The feasibility of using crumb rubber concrete (CRC) in airport pavement is discussed by analyzing the capability of crumb rubber concrete. The bending property of CRC is studied by four point loading test of small-sized rubber concrete beams. Comparing with cement concrete (CC) pavement, the board thickness of CRC pavement is analyzed. The conclusions are reached that appropriate mixing of crumb rubber could satisfy strength demand and improve durability of airport pavement, and the thickness of CRC pavement is 93 percent of that of CC pavement. As a result, airport CRC pavement has longer service life and perfect cost performance.

Abstract: The impact resistance of steel fiber reinforced lightweight aggregate concrete was presented in a drop weight test. In this test, 5 groups of disc specimens with different steel fiber volumes including 0.0%, 0.5%, 1.0%, 1.5% and 2.0% were tested. The experimental results indicated that the impact resistance of lightweight aggregate concrete is improved with the increase in fiber volume. As the variation in experimental results, a statistical evaluation was performed to study the influence of impact resistance of steel fiber reinforced lightweight aggregate concrete with different steel fiber volumes. Further more, the impact resistance was simulated with probability distribution by Log-normal method. And the goodnees-of-fit tests indicate that the Log-normal method has good fitness to the impact resistance of steel fiber reinforced lightweight aggregate concrete.

Abstract: Effect of packed structure on behavior of capillary absorption was briefly reviewed. Silica fume blended cement was pressed at pressure of 18MPa in a special mould to prepare packed structure. Structure of blended cement compacts was characterized by method of capillary ethanol absorption. Results show that linear correlation coefficient between absorption weight and square root of absorption time for each compact is more than 0.999. Micro silica fume is randomly filled into the skeleton of the compact. With increase of silica fume addition, porosity of the compacts and total length of average capillary pore in the compacts increase, whereas diameter of average capillary pore decreases. Quantified characterization of structure of the blended cement compacts will benefit to research of design and control of cement materials.

Abstract: This paper presents an experimental study on sand-lime bricks. The purpose of this research is to examine different materials as modifiers, in particular barium aggregate. Undoubtedly, the properties of the sand-lime products depend on many factors such as raw materials, preparation or autoclaving conditions, etc. The research was carried out and analyzed by scanning electron microscope (SEM) in order to improve acoustic isolation of calcium silicate bricks. As a result, it was possible to determine the phase composition in the structure of the calcium silicate products.

Abstract: 16 groups of compressive strength with different mix proportion of lightweight heterogeneous soil mixed with expanded polystyrene (EPS-soil) has been gained by means of orthogonal test. Regression model is obtained, checked and evaluated by linear regression .48 groups of EPS-soil’s compressive strength is predicted by using strength predictable formula. Results show that: the formula’s precision is high and satisfy the actual need of project.

Abstract: The purpose of this study was to improve the durability of fly ash concrete. As a result, by making fly ash concrete into non-air-entraining type and using durability improving admixture, the compressive strength of fly ash concrete increases 10%~30%, reducing initial compressive strength defects; drying shrinkage is controlled at 60% compared to when the mixture is not added; carbonation of fly ash concrete can be considered roughly proportional to water-cement ratio regardless of water-binder ratio or fly ash replacementratio; the freeze damage resistance improves for 2 weeks curing in air (drying process). Finally, by making fly ash concrete from non-air entraining type and using durability improving admixture, the difficulty of controlling air content in fly ash concrete is reduced and quality management is simplified.