Advanced Materials Research Vols. 194-196

Abstract: To prevent improper design and construction of fire compartments through-penetration in buildings, and in order to reinforce public building safety management, all beams, pillars, ceilings, floors, doors, walls, and interior decorative materials must have fireproof properties. Moreover, cable conduits, water pipes, and air ducts located in through-penetration sites within buildings should be properly designed to block the spread of smoke and hot air, thus, reducing losses due to fire disasters. This study used common firestop materials, such as firestop sheets, mineral wool, and two-pack fire barrier foam to conduct 10-min surface burning tests on individual substrates. The flame spread distance and smoke per minute were measured and recorded in order to calculate the Flame Spread Index (FSI) and Smoke Developed Index (SDI). The results showed that all three firestop materials meet with the ASTM E84 Class A.

Abstract: PSt/GMA/DVB microspheres were prepared by soap-free emulsion co-polymerization of St, GMA and DVB monomers. The fractional conversion of polymerizations was characterized by gravimetric methods. All the fractional conversions of polymerization exceeded 90 percentages. The amounts of epoxy groups on the microspheres were measured by hydrochloric acid- acetone method. The results showed that the added time of GMA monomers had little influence on the amounts of epoxy groups in the microspheres; however, with the increasing of GMA monomers, the epoxy groups increased; with the increasing of DVB monomers, the epoxy groups drastically decreased.

Abstract: The formation process of a petal-like morphology on the surface of porous anodic alumina (PAA) is discussed in detail. During the anodizing process, the electronic current is produced within the growing oxide, which results in the oxygen evolution at the pore bottom. The pressure of the oxygen bubbles increases along with the anodizing process, and their high pressure acts as a driving-force of the micro-gas-flow, resulting in the micro-liquid-flow in the pores of PAA. The micro-liquid-flow can flow into each other between a center pore and the nearest neighboring pores. The nanogroove between two pores can be formed due to the dissolving effect during the process of micro-liquid-flow between the two pores. This leads to the formation of the petal-like morphology on the PAA surface. As the micro-liquid-flow leaves off the pore bottom, there a local vacuum is formed. This local vacuum behaves as a driving-force of the micro-liquid-flow, making the electrolyte renovated in the nanopores. The renovated electrolyte can provide enough anions or impurity centers, which are the cause of the generation of the electronic current. The self-organizing for the petal-like morphology on PAA surface is mainly dependent upon the high pressure of the oxygen bubbles and the local vacuum produced at the pore bottom. The present results may help us to understand the nature of the self-organization in the porous anodic oxides.

Abstract: Crack will not only do harm to structure of concrete but also destroy durability of concrete project. The influence of fly ash on crack resistance of mass concrete was studied in this paper. We can decrease brittleness of mortar, elastic modulus, dry shrinkage, adiabatic temperature rising, autogenous deformation and increase creep of concrete by adding fly ash, and present relationship between content of fly ash and elastic modulus of concrete. In short, we can improve crack resistance of mass concrete by adding fly ash.

Abstract: In this paper, mechanism of anisotropic material of thermal conductivity was revealed by rotating the original rectangular axes so as to determine the principal axes and make the cross-derivative terms disappear. The results indicated that the heat flux vector is commonly not perpendicular to the isothermal surface in anisotropic material. The advantage of anisotropic material of thermal conductivity was analyzed. The application of laminated composite with anisotropic thermal conductivity in double skin envelope was proposed to avoid its disadvantage. The interior envelope in double skin system may be made of laminated glaze or other laminated materials. Basing on the combine of anisotropic material and double skin envelope, the indoor cooling and heating load decrease in summer and winter respectively while the anisotropic material was used as interior building envelope. Especially in summer, the effect of energy saving is obvious since the partial magnitude of conductive heat in the interior envelope could be brought out from the cavity by natural ventilation through it.

Abstract: In this paper, the background of concrete structure strengthen is described, and several common methods of strengthening concrete structure in current construction are introduced. Also the advantages and disadvantages application of reinforcement methods are discussed. so as to valuable experiences for strengthening reinforced concrete structures are accumulate. Both the advantages and disadvantages of the reinforcement methods are described in detail. For example, the increasing cross-section reinforcement method, the replacing concrete reinforcement method, the bonding steel reinforcement method, the pasting steel reinforcement method, the pasting fiber reinforced plastic reinforcement method and so on. And so many accumulated experiences are provided for later strengthening reinforced concrete structure, and the process of strengthening concrete structure is improved.

Abstract: According to experimental research on 10 specimen of steel bars under fatigue loading, remained static strength of bars has been measured. On the base of experimental data, a new fatigue strength (limit) measuring method of steel bars using in concrete structure has been set up. Experimental results and theoretic analysis show that the method can shorten time in experiment, reduce discreteness and improve the precision of data. The method may be used to measure fatigue limit of both not corroded and corroded bars (especially with local unsymmetrical corrosion pits) bearing fatigue loading, therefore it will be used to evaluate the residual fatigue expectation of reinforced concrete that bearing fatigue loads such as bridge structure which has served for a certain long of time and be used to make right decisions on repairing or removing structures under reversed loads.

Abstract: The paper studies the modification mechanism of asphalt rubber blending system by means of scanning electron microscopy, infrared spectroscopy, differential thermal analysis, component analysis and chemical analysis. The results indicate that the swollen rubber powder is mutually-adhered to form a network structure and the matrix asphalt changes from homogeneous body into a two-phase continuous blending structure system constituted by rubber powder and asphalt; physical swelling dominates the system, accompanied by a little chemical reaction and with the prolongation of time, the chemical reaction becomes more obvious; the swollen rubber powder forms damping effects to improve the viscosity of rubber asphalt. The modification of asphalt comes from two aspects: firstly, the network structure formed by swollen rubber powder, secondly, the modification of the asphalt composition resulting from rubber powder desulphurization degradation; the natural rubber has better performance in modifying asphalt than synthetic rubber.

Abstract: This study centered on the development of constitutive model of the material based on damage mechanics. Volumetric expansion, unilateral behavior and softening effect have been pointed out as three difficulties during setting constitutive model of concrete, the applicable and deficiency of the existed constitutive relationship been reviewed, and the methods used to deal above difficulties were overviewed, Meanwhile, the background of existed model has been summarized and listed systematically. The development of a thermodynamic approach to constitutive model of concrete, with emphasis on the rigorous and consistency both in the formulation of constitutive models and in the identification of model parameters based on experimental tests has been potential direction of the future study, and hoped furnished basement for the elastic to plastic coupled damage mechanics constitutive model of concrete.

Abstract: For the situation that concrete engineering required rapid and timely repair after nature disaster, setting time and influencing factors of phosphate rapid repair material were studied in this paper. The results showed that setting time of phosphate rapid repair material increased a little with increase of water and binder ratio but the setting time was short. When water and binder ratio was less than 0.20 setting time was less than 3min. Setting time was shorted with reducing of P/M. Setting time was from 2min30s to 5min when P/M was reduced from 1:0.6 to 1:4. Setting time of phosphate cement increase a little mixed with fly ash, slag or portland cement but effect of their content on setting time was little. Setting time of phosphate rapid repair material increased with increase of B/M. When content was greated than 12% the setting time was longer than 20min. Fly ash, slag and portland cement can reduce setting time of phosphate cement with borax obviously.