Advanced Materials Research Vol. 811

Abstract: New Generation Large Aircrafts became a new member of China large airports. However, its heavy weight and high contact pressure would have great impact on the flexible runway pavement. in this paper, based on the multilayered elastic theory, the tensile stress distribution under different airplane was studied to obtain the critical load positions. Furthermore, parameter sensitivity analysis was conducted, including thickness and modulus of Asphalt Stabilized Base (ATB) layer. Results indicated that increasing ATB thickness can only decrease the tensile stress a little, and increasing the modulus of the ATB layer will be more efficient than increasing its thickness. Finally pavement design suggestions composing of both the structural and material considerations were proposed.

Abstract: The objective of this study is to investigate and evaluate the effect of coarse aggregates (aggregate size bigger than 2.36 mm) on the compressive strength and creep behavior of asphalt mixture. The variable that is mainly considered in the study is the gradation degradation of coarse aggregates. A kind of standard aggregate gradation and three kinds of degraded aggregate gradation mixture specimens are used. Uniaxial compression and static creep tests were realized at different loading conditions and temperatures. The test results on asphalt mixture showed that the compressive strength and creep behavior of asphalt mixture are significant affected by the different coarse aggregate gradations.

Abstract: The response analysis of a large cable net bearing wind load is conducted by the nonlinear finite element method. First, the form-finding calculation of the cable net structure is carried out to find an equilibrium state which can make the pretensions and sags of the wires meet the given requirements. Then the static analyses of the finite element model of the cable net structure under different wind loads are conducted to assess whether the cable net structure meets the requirements for strength. The work of this paper establishes the foundation for the design of a large cable antenna.

Abstract: Hangers are the critical elements supporting stiffening girder in suspension bridge. The hangers probably break suddenly in service for the reasons of corrosion, fatigue or traffic accident. Because the hangers are anchored to the main cable, the sudden breakage of hanger causes strong vibration of main cable, and the vibration may damage some of the elements of the bridge. Using nonlinear dynamic analysis methods and adopting 3D finite element model, the responses of a suspension bridge to sudden breakage of hangers are studied in this paper. The results show that the sudden breakage of hanger has significant effects on tensions of the hangers adjacent to the broken hanger, the maximum tension of hanger produced by breakage of a hanger exceeds 2.2 times of its initial value, and the tensions of other hangers far away from the broken hanger are affected little. The breakage of a single hanger causes very large torsion moments of girder and reactions of bearings, but it has little effects on the tensions of main cable and moments of tower.

Abstract: APC (air pollution control) fly ash, generated in incineration process of municipal solid waste, is regarded as a hazardous waste because of enrichment of heavy metals. In this work, stabilization of the ash with cement was studied. In addition, XRD analysis of the cement stabilized body was performed as a function of conservation time period. It was It was found that the hydration products cement fly ash and other particles together, which rises with increase of the cement / ash ratio and duration of conservation. Major mineralogical compositions CaCO₃, Ca (0H)₂ and C-H-S hydration products. Content of Ca (0H)₂ and C-H-S rises with increase of conservation period and cement / ash ratio.

Abstract: Reactive powder concrete (RPC) has been proposed as barrier materials for the construction of engineered barrier in Taiwan. The durability characteristics of RPC in such applications become paramount for the success of the containment of the wastes. The adverse environmental conditions at the disposal site could attack concrete barrier and results in degradation of the material.Laboratory tests will be conducted on RPC with various compositions to investigate the durability test of RPC. These include chloride ion ingress, and sulfate attack of RPC. In this study, the resistance of concrete to sulfate attack was tested by submerging RPC specimens in Na₂SO₄ solution. Based on the volume change data for a period of1 year, the RPC with higher water to binder ratio (W/B) exhibited lower resistance to sulfate attack. The electrochemical technique is applied to accelerate chloride-ion migration test for RPC. The RPCs chloride migration coefficient is significantly decreased by the use of pozzolanic material, compared with ordinary concrete.

Abstract: Experiments on influence of species of aggregate and mixing method on interfacial zone in recycled aggregate concrete were investigated. SEM observations revealed that a recycle normal-strength concrete aggregate consist of loose and porous interfacial structure, whereas a recycled high performance concrete (HPC) aggregate and a triple mixing (TM) consist mainly of dense hydrates. Various admixtures on ITZ was produced that consumed CH in the pore, modified attached cement mortar. Strength of recycled concrete was explained by interaction between cements paste and recycled aggregate. The result verified that the relatively dense pore structure of the recycled concrete benefit to development of mechanical properties.

Abstract: Recycled aggregate concrete (RAC) differ from natural aggregate concrete in mechanical and durability properties. The poorer qualities of recycled aggregate (RA) limit utilization of RAC in engineering. Cement mortar attached on the surface of recycled aggregate result in higher water absorption rate. Also, interfacial zone between recycled aggregate and new mortar consist of loose and porous hydrates. Investigation is devoted to effects of different approaches on improving performance of RA to compensate the lower quality of RA. The pre-soaking treatment approach reduces the old cement mortar and removes the weaker link in interfacial zone. Moreover, The two-stage mixing approach (TSMA) is adopted, leads to the formation of a thin layer of cement slurry on the surface of RA which permeates into the porous old cement mortar, filling up the old cracks and voids for increasing compressive strength. Correlations in methods have been obtained and discussed.

Abstract: Major objectives of this study are to evaluation the enrichment, accumulation, and potential ecological risk of copper (Cu) in the surface sediments of southern Kaohsiung Harbor, Taiwan. Twelve sampling locations were installed of southern Kaohsiung Harbor to collect sediment samples for analyzing Cu. Results showed that the Cu concentrations varied from 6.0953 mg/kg with an average of 132±165 mg/kg. The spatial distribution of Cu reveals that the Cu concentration is relatively high in the river mouth region, and gradually diminishes toward the harbor entrance region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of Cu pollution. Results from the enrichment factor and geo-accumulation index analyses imply that the sediments collected from the Salt River mouth can be characterized very severe degree enrichment and strong accumulation of Cu, respectively. Results of potential ecological risk index indicate that the sediment has low to higher ecological potential risk.

Abstract: Precipitation runoff is the main driving factor which leads to soil erosion and nutrient transfer. In the experiment, an artificial rainfall simulator was used to study the migration amount of organic matter, nitrogen, phosphorus and potassium, volume of the soil erosion and its particle size composition in the earlier runoff, under a certain condition of rainstorm intensity and different slopes. The test results show that the migration amount of nitrogen, phosphorus, potassium, etc. is more than 70% of the respectively total loss in the first 30 minutes of runoff. Under different slope conditions, clay content in the runoff sediment within the first ten minutes is more than subsequent 10min and the rest time. According to the test results, under different slope conditions, there are obvious initial flushing effects of storm-runoff.