Advanced Materials Research Vols. 168-170

Abstract: With the increasing popularity of pervious concrete as a pavement material, researchers and concrete manufacturers have paid more attention to research needs. Pervious concrete is currently used in low traffic volume areas such as parking lots, footpaths and driveways. This is because it generally has lower strength than conventional concrete. This paper aims at developing a computational model to simulate the behaviour of pervious concrete under compression. Since compressive strength is one of the most important properties for concrete, a virtual model will provide a better understanding of its mechanical performance, which in turn will improve both the mix design and the material strength in the future. The discrete element method was applied and the results of calculations based on particle flow analysis are compared to the experimental data.

Abstract: The solar chimney power station is a renewable energy system consisting of solar collector, wind turbine, and chimney. To improve the efficiency of energy generation, the higher chimney is the better. Considering the difference between the solar chimney and the traditional high-rise structure, the study on the chimney from the structural point of view is produced in this paper. The existing and planed chimneys are first introduced. Then the solar chimney is classified according to material, structural system, and constraint condition. Followed that, application of prestress technology including adoption of prestressed concrete, introduction of circumferential prestress, arrangement of stayed cable or cable net, and utilization of tensegrity system in the solar chimney is involved, which can improve the structural behavior of the chimney significantly. On this basis, conceptual models of three different structural systems are designed, and the performance of the models is tested under the horizontal force to show the effect of stayed cable and spokewise cable.

Abstract: A new method for transformer fault diagnosis based on cluster analysis and statistical theory is presented. First, the fault diagnosis results are obtained according to the distances between the state sorts of transformer. Then, the final fault diagnosis is accomplished according to the concentration distribution of typical fault gases in higher dimensional space. The proposed approach is constructing the most accuracy model from few training samples supporting. Moreover, by comparing with the other methods, it cost less time for diagnosing by the proposed model and the accuracy for transformer fault diagnosis is improved using our proposed model.

Abstract: In order to study the effect of fibers to the anti-crack performance of the concrete, sixteen different plat restraint specimens with four different fiber mixing amount (steel fiber is 0, 0.5%, 1%, 1.5%, and polypropylene fiber is 0, 0.1%, 0.2%, 0.3% respectively), are selected to comparison about the influence on the anti-cracking property of the hybrid fiber concrete, single fiber reinforced concrete and plain concrete. Experiments show that fibers increasing the anti-crack performance of the concrete significantly. The relationship between fibers’ content and the crack area is analyzed, and the microscopic mechanism of the anti-crack performance is discussed. Considering the economy and the convenient for construction, the column ratio of 0.5% steel fiber and 0.1% polypropylene fiber is recommended.

Abstract: FRP (fiber reinforce polymer) rubber bearing is a novel isolator improved from traditional laminated rubber bearing. Several specimens were manufactured to study the mechanic properties of FRP rubber bearing. Vertical experiments are conducted to study the compression capacity and compression modulus of the bearing and horizontal experiments are conducted to study the shear modulus and damping property of the bearing. Hysteretic curve and damping ratio of each specimen are derived from the experiments. The results show that the performance of FRP rubber bearing matches that of multiplayer rubber bearing but have good damping capacity.

Abstract: Industrial wastewater sludge contains a certain amount of heavy metals, which will cause environmental pollution. In this paper high Cr, Zn content wastewater sludge from steel plant was used as the main raw material, with Kaolin and other materials as adjustment materials. Through optimization design of raw mix composition and firing system, a kind of function aggregate was got, which had an apparent relative density of about 3.0 g/cm³, a vacuum water absorption between 16%~23%, and a linear attenuation coefficient more than 0.15cm^-1. Use XRD and SEM to analyze the existence state of heavy metals in aggregates. The novel method for making function aggregates provides a technical support for resource utilization of steel wastewater sludge, which could be applied in the field of high strength concrete and radiation shielding concrete.

Abstract: There is a fast moving trend towards using lightweight materials in automotive, aerospace, building and construction, body armour and protection, sports and leisure goods. The dynamic industrial development puts higher demands for lighter and yet stronger materials. Magnesium alloys potentially met the present demands for lighter and reliable construction. With comparable specific stiffness, higher specific strength and energy absorption magnesium alloys have the potential to replace steel and aluminum alloys. Magnesium alloys are very useful for applications where materials are subjected to variable or dynamic loads such as crash events in vehicles and planes, buildings and structures against projectiles penetration etc. To know the materials’ response to impacts and their resistance to blast and shock, it is necessary to understand their behaviour under static as well as dynamic conditions. In current study, magnesium alloys AZ91D and AM50 have been studied at dynamic loading conditions and compared with aluminum alloy AA6061-T6. With significant mass saving, higher specific properties and higher energy absorption under dynamic loadings, magnesium alloys are promising candidates to replace conventional materials not only aluminum but steel as well in structural applications.

Abstract: The work presented in this paper focuses on the molding technical and mechanical properties of cotton stalk block. Cotton stalk block is a new type of ecological filling materials. The previous test data and practical experience show that the major three factors affecting the compressive strength of the block are the glue consumption, the density of block and the sand content of block. In this paper, the method of orthogonal experiment is used to analyze the molding technology of cotton stalk blocks and the above three factors (glue consumption, density and sand content of block). The research results show that, the glue consumption and the density have significant effect on the compressive strength of the block, but the effect of sand content of block is less. In additional, an optimal combination of the three factors is obtained. Based on this combination, the compressive strength of the block can reach to1.55 MPa, which can meet the strength requirement of the filling materials.

Abstract: The packing density of the powder in cement paste has great influence on the performance of the concrete. A higher packing density could at the same water/powder ratio increase the amount of excess water for lubricating the cement paste and thereby improve the flowability of the concrete. Alternatively, it would allow the water/powder ratio to be reduced to improve the strength of the concrete without compromising the flowability. Therefore, it is of great interest, especially for production of high-performance concrete, to maximize the packing density of the powder. This study aims to investigate the roles of superplasticizer and fillers in the packing density of the powder in cement paste. Packing density tests were carried out to determine the packing density of cement with various dosages of superplasticizer and different fillers (limestone fine, superfine cement and condensed silica fume) added using a newly developed wet packing method. The results showed that the addition of superplasticizer can significantly improve the packing density of cement while the addition of fillers can further improve the packing density of the powder.

Abstract: This paper introduces performances and characteristics of concrete bar-type plank, a new type of building materials, through detailed graphics recording its applications in State Key Laboratory for Green Building Materials. Also, it proposes issues in further research and potential direction for concrete bar-type plank development widespread used in actual projects, i.e., to become an exterior wall structure system rather than a simple decorative component.