Advanced Materials Research Vol. 684

Abstract: Classical coaxial plasticity constitutive models implicate an inevitable limitation that directions for principal stress and that for principal plastic strain increment are always coaxial. They are not capable of simulating non-coaxial phenomena during the rotation of principal stress axis. In this paper, a three-dimensional, non-coaxial plasticity constitutive model for sands with a modification of Lade angle dependent shape function is introduced to describe the non-coaxial behavior under principal axes rotation. A series of numerical simulations of hollow cylindrical torsional shear tests are performed. The results show that the proposed constitutive model can predict the variations of principal plastic strain increment directions with principal stress directions reasonably.

Abstract: The landslide with static liquefaction often occurs in loose fill slopes with silty sand for the rainfall, causing lots of casualties and property loss. This study performed a series of static CU triaxial tests to investigate the influence of Bentonite content on the static liquefaction behavior of sand. The results indicate that there exists a critical value, below what increasing the Bentonite content reduces the resistance to static liquefaction. However, above the value the resistance to static liquefaction is increased with the rise of Bentonite content. This conclusion can be applied to manage the disaster triggered by the landslide with static liquefaction.

Abstract: Many researches on coal gangue are aimed at increasing its activity by many methods together such as thermal, mechanical and chemical. The methods are so complex that they are difficult to be adopted by some companies. In this paper, considering the low-strength requirement of cement mortar, the activity of coal gangue is more evidently shown by Ca(OH)2 activator. The 28-days strength of coal gangue cement mortar can reach 18MPa and the hydrated mortar shows and keeps an expansive behavior by adding methyl cellulose ether and CaSO4•2H2O at all the ages.

Abstract: Concrete failure surface is the most important tool to predict concrete strength under complicated load. Most concrete structures in cold regions are subjected to both external loads and freezing-thawing, while now most researchers focused on the freeze-thaw durability of concrete without external loads. To make up the deficiency, the degradation of compressive strength of concrete under the simultaneous action of external loads and freezing-thawing are experimentally investigated in this research. Finally, a concrete failure criterion is adopted to establish an applicable failure surface in principal stress space for concrete.

Abstract: Phase change material possesses excellent heat storage performance that can provide some advantages to buildings. This paper introduces the properties of the phase change material , discusses the criterion of the phase change material that can be used in architecture, analysis the principles about the architectural application of phase change material, and especially discusses the ways how to use the phase-change energy storage materials for construction in building energy efficiency. Besides, this paper also analysis the future prospects and some problem still existing.

Abstract: To enhance the mechanical and compressive strength of lime mortar(lime-sand ) the fly ash was added to the compound to improved the engineering performance of lime mixture .The addition of fly ash and lime stone dust to clay soils reduce their plasticity characteristics, swell potential and improve their compressive strength (Brooks et al. 2011) .Boardman et al (2001) observed that no significant pozzolonic activity appears to take place until 7 days of curing during their experiments at room temperature .In this research the effect of fly ash at different range from 30 to 70 percent of mix by varying lime percentage from 6 to 20 percent with thermodynamic parameters of their reaction was assessed in normal and raised temperature by curing compacted specimens in the laboratory .The compressive strength of fly ash and lime mixture are determined on curing period up to 28 days in normal state and one days on raised one .The Result portrayed that raised temperature highly boosted the compressive strength of the mix from 30 to 120 percent at different range of fly ash mixture with lime.

Abstract: An experimental research of the bonds amongst retrofitted materials on concrete structures under seashore climate has conducted. The strength of a bond between repair materials and concrete substratum has been assessed on the base of slant shear test experiment. In this research 52 samples has prepared and used for experiment .The fresh concrete with fine aggregate mix only (less than 9mm particle size without coarse aggregate) and 14% silica fume by weight of cement (normally 8 to 10% but 14% because of high amount of fine aggregate ) added to the mix which improve the properties of concrete such as bond strength as well as compressive strength and reduces permeability of sea water in corrosion or deterioration of steel bars by protecting reinforcing steel from erosion (pivotal aim of research) and even reduces abrasion resistance .Therefore silica fume was rolled an essential repairer materials on seashore structures. The retrofitted specimens were cured on water pool and kept on the seashore simulation climate upto required curing times . The strength of the improved samples has studied in three aspects as bond strength according surface roughness ,curing periods and concrete additives like silica fumes and fibres .

Abstract: To improve the compatibility and dispersion of the sepiolite in polymers, a surfactant of octadearyl dimethyl ammonium chloride（OTAC）was used to modify sepiolite. The experiment was used to analyze the effects of OTAC dosage, reaction temperature and reaction time on the wettability of organically-modified sepiolite. The effects on the structure performance of sepiolite were investigated by XRD, SEM and contact angle measurements. The orthogonal experimental esults show that the optimum amount of OTAC, reaction temperature and reaction time are 400 mmol/kg, 90 °C and 120 min, respectively.

Abstract: Municipal solid waste (MSW) landfills are one of the major source of hydrogen sulphide (H2S) which is the offensive odours potentially creating annoyance in adjacent communities. This project focuses on H2S emission from landfills in Perlis, Malaysia. Landfill gas (LFG) samples were collected and analyzed accordance with NIOSH method 6013. The mean concentrations of H2S in Kuala Perlis Landfill and Padang Siding Landfill are 210.68 ppm and 242.85 ppm respectively. High concentrations of H2S may be a concern for employees working on the landfill site. These results indicate that workers should use proper personal protection at landfill when involved in excavation, landfill gas collection, and refuse compaction. The formation of H2S most likely to be contributed by the biological conversion of sulfate from gypsum-rich soils and landfill wastewater treatment sludges by sulfate-reducing bacteria (SRB) which can utilize dissolved sulfate as an electron acceptor. H2S is conveniently detected by hand held analyzer, such Jerome meter, landfill gas analyzer. In the organic range, in the ease of detection range in the dispersion rate within the landfill site, the monitored H2S gas form a very noticeable concentration with the travelling wind direction. It proved that the dispersion rate of H2S are suitable as tracer to detect route of travelling in a certain distance.

Abstract: The effect of contact time and the determination of the kinetic parameters of adsorption of methyl orange (MO) from aqueous solution onto Iron-Oxide-Coated-Zeolite (IOCZ) powder are important in understanding the adsorption mechanism. The effect of contact time on adsorption quantity was studied at different initial concentration and temperature, respectively. The pseudo-second-order model was adopted to fit the experimental data using non-linear regressive analysis and it was used to predict the adsorption behavior. The results showed that the process of adsorption MO was endothermic and chemisorption. The pore diffusion was not significant.