Applied Mechanics and Materials Vols. 71-78

Abstract: In this study, in order to evaluate the migration of heavy metals in enhanced electrokinetic removal，visual minteq was adopted to calculate the species distribution of heavy metals in different pH. Most of the heavy metals except arsenic generated the enrichment near the cathode area. Arsenate always existed as anion such as AsO₄^3-、H₂AsO₄^-、HAsO₄^2-. Near the alkaline area ,the main form of heavy metals were alkali metal hydroxides and seriously restricted the migration and removal of heavy metals. The addition of potassium tetroxalate did not change the species distribution of heavy metals obviously.The nitric acid was more efficient than potassium tetroxalate to condition enhanced electrokinetic removal. Nevertheless ,both of two enhancement still need to be impoved to promote the removal efficiency.

Abstract: According to the data of carrying capacity of concrete columniation in seawater in different circulation times, a non-liner regression model is established between circulation times with carrying capacity of concrete columniation in this paper. The parameter is calculated by Genetic Algorithms, and then the carrying capacity of concrete columniation is calculated with the model. Good agreement is reached between the theoretical calculations with test results; the average relative precision is over 92%. As a result, it can be used to analyze the carrying capacity of concrete columniation in seawater. This analysis method is intelligent.

Abstract: Basing on the new developed direct shear testing instrument, the biodegradation strength properties and strength parameters of municipal solid waste with higher content of organic matter have been studied. The municipal solid waste is divided into three parts: the material that is easy to be biodegraded, reinforced material that is difficult to be biodegraded and the incompressible solid waste material. The proportions of these three parts are 80%, 5% and 15%, respectively. A series of laboratory tests have been performed for different initial void ratios and different vertical pressures applied on the test specimen. Testing results show that the initial void ratio is the main influence factor for the biodegradation strength of the municipal solid waste, the relationship between the biodegradation shear stress and the shear strain is a strain hardening curve, the biodegradation shear stress gradually increases with the shear strain. Besides, the biodegradation shear strength shows a linear relationship to the vertical pressure applied on the test specimen, and it is in accordance with the law of coulomb. According to the testing results, the biodegradation shear strength parameters of municipal solid waste are obtained. The cohesion varies from 11.5 to 24.0kPa, and the internal friction angle varies from 8.3 to 29.0 degree.

Abstract: The ductility of member is important as the intensity. For the ductility of member, the ductility of steel bar used in the member should be limited. In this paper, the safe extent of elongation of steel bar used in reinforced concrete flexural rectangle section member is calculated with the analysis of theory. This paper provides a thought and a simple method to prevent the brittleness destruction of member.

Abstract: Nowadays, there are dominantly two ways of producing modified emulsified asphalt ,one of which is to emulsify modified asphalt, the other to modify asphalt emulsion. But they have the same defect that modifier cannot be evenly mixed with asphalt emulsion, which has side effect on the performance of modified emulsified asphalt. The emulsified asphalt and modifier have different traits in structure and property. In order to make the modifier disperse in asphalt emulsion evenly to improve the performance of modified emulsified asphalt, a tentative idea is brought forward: we shall utilize in-situ polymerization and core-shell structure to enhance feature of emulsified asphalt. Core-shell structure is a method of synthesizing composite material, which can assist to achieve sound effect of the two kinds of materials. The point to emphasize is, in this paper, the introduction and feasibility of the method, its specialty against current mainly methods, the difficulties encountered in practice as well as its promising prospect and the anticipated target to achieve will all be illustrated.

Abstract: Base on two groups of comparison tests of bearing capacity of three rectangle section of steel concrete beams with different strength grades, the research analyzed the effect of concrete beams strengthened by carbon fiber sheet and strengthened jointly by carbon fiber sheet and external prestressing on the bearing capacity, failure modes, strain states, rigidity and ductility.The results show that bending resistance of steel concrete beams strengthened jointly by carbon fiber sheet and external prestressing can be improved obviously, and the usage performance and strengthened effect are obvious too.

Abstract: The durability of concrete structure has become an important field of civil engineering at home and abroad, and how to determine the environmental effects of typical durability of concrete structure key parameters become the key. Proposed by different domestic and foreign scholars to study durability parameters of concrete structure of different models, different models are different in the source, type, model parameters and applicable conditions. In this paper, some typical models are reviewed and analyzed from two major aspects of the durability of concrete, the deterioration of concrete and the steel corrosion.

Abstract: This work describes the platinum-containing cordierite nanocomposite materials were synthesized by incipient wetness impregnation process with aqueous solutions of H₂PtCl₆, Pd(NO₃)₃ and Rh(NO₃)₃ that were coated on cordierite ceramic honeycomb substances followed by calcinations temperature ranging from 973 to 1273 K. The nanocomposite materials were characterized by STEM, with a particle size around nanoscale particle sizes (~100 nm) with high dispersion phenomena. Further, cell cytotoxicity and the percentage cell survival was determined by using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetrazoli um (MTS) assay on human fetal lung tissue cell (MRC-5). The experimental results show that the platrinum-containing cordierite nanocomposite materials only minor cause cytotoxicity effect in cultured human cells.

Abstract: An experimental program was carried out to obtain the density and compressive strength of lightweight expanded polystyrene (EPS) concretes. Tauchi’s approach was adopted to reduce the numbers of experiment. Four control factors and two responses were used. The results show that EPS dosage had the most significant effect on density and compressive strength. The density value of EPS concrete showed an almost linear decrease as the volume of EPS and W/C parameters increased, but results in a decrease in compressive strength.

Abstract: Experiments were conducted on 5 simply-supported composite steel-concrete beams (SCB) with compact steel sections to investigate their deflection behaviors. The influences of degree of shear connection and stud arrangement are discussed. The load-deflection relationships and the interface slip distribution along the span of the beam are analyzed. Based on the experimental research and theoretical analyses, the formulae are derived for the rigidity of the composite steel-concrete beams with partial shear connection. The predicted of deflection values are in good agreement with the experimental results.