Applied Mechanics and Materials Vols. 584-586

Abstract: Quantitative X-Ray Diffraction (QXRD) with Rietveld full pattern fitting method and the hyphenated technique of ThermoGravimetry (TG) with Differential Scanning Calorimetry (DSC) were used to explore the effects of silica fume (SF) on hydration process of composite cementitious system (CCS) as well as the pozzolanic reaction (PR) of SF in this system. Results indicate that the PR of SF has started at the end of the first day but proceeds very slowly during the rest days due to the agglomeration of SF particles; and the starting point of PR is far earlier than that of drop of CH content, which implies that it is not suitable to mark conventionally the drop of CH content as the starting point of PR.

Abstract: To solve the problem of early-age concrete shrinkage under constraint, 0%, 2%, 3%MgO expansion agent are mixed in the concrete. Results indicate that MgO expansion agent can ensure the expansion strain of the concrete and produce the self-stress under constraint which is up to 1.8Mpa~2.2Mpa.

Abstract: Reinforced concrete eccentric frame-shear wall structure has been widely used in engineering. However, this structure is mainly used for high-rise structure, and it is difficult to obtain accurate earthquake response of structure through experimental study. Therefore, simulation software needs to be used for study on seismic performance of high-rise structures. This paper produces useful conclusions for the project through shaking table test and the simulation of seismic performance provided by ANSYS finite element analysis software.

Abstract: Modification of wood surface with compositions produced on the base of boric acid esters of amin-alcohols increases its polarity, decreases specific surface area and reduces water absorption of wood twice. This improves wettability of water surface and increases adhesion strength of paint coating which is the result of intermolecular forces of interaction. The latter provides increases service life of paint coating.

Abstract: The stuctural, elastic and thermodynamic properties of B2-NiAl and L1₂-Ni₃Al intermetallic compounds are systemically investigated. Using a first principle pseudopotential plane-wave method, several basic mechanical parameters of B2-NiAl and L1₂-Ni₃Al crystals, such as the equilibrium volume, the bulk modulus, the elastic constants, the Zener anisotropy factor, the Poisson’s ratio, the Young’s modulus and isotropic shear modulus are firstly calculated. And then the temperature dependence of the equilibrium volume, the bulk modulus, the thermal expansion coefficient, the heat capacity, the Debye temperature and the Grüneisen parameter are further evaluated in the framework of a quasi-harmonic Debye model. Finally, a special attention is paied on the mutual influence of pressure and temperature on mechenical and thermodynanic properties of B2-NiAl and L1₂-Ni₃Al intermetallic compounds in the range of 0-20 GPa and 0-1000 K.

Abstract: Based on orthogonal design method, a kind of alkali-free liquid accelerator is successfully developed by adopting aluminum sulfate, DL-Lactic acid, triethanolamine, glycerol, phosphoric acid and other raw materials. The initial setting time of the accelerator is 2min50s, and final setting time is 6min30s. The compressive strength ratio of 28 days is 103.5%. All the indices meet the first class requirements in Flash setting admixtures for shotcrete (JC477-2005). It is also provided with better adaptability. Finally XRD testing method is adopted to reveal the fast-setting mechanism of alkali-free accelerator.

Abstract: In this study,different particle size’s aggregates ,different aggregate correction coefficients and different sand ratio were selected to study the aggregate’s influences on properties of porous pervious concrete made of recycled aggregates.The results shows that the 28-day compressive strength of concrete with single particle size is lower than those with two kinds of particle mixing ,as for the permeability coefficient, the former is much higher than the latter .With the aggregate correction coefficient’s increase,the 28-day compressive strengths of concrete increases first and then decreases, the permeability coefficient increases . The 28-day compressive strengths of concrete increases with the increase of the sand ratio. the permeability coefficient increases first ,decreases then.

Abstract: In the case of fixed powder paste, changes in the sand ratio have an impact on the workability of concrete. According to Mehta and Aitcin’s ideas for the preparation of HPC, regard the powder as cementing material and the powder paste as cementing material paste. Investigate the influence of sand ratio on concrete performance when the powder paste reaches the fixed number 350L, the concrete optimum performance. When the sand ratio is 37%~41%, in the case of causing minimal impact on the strength, you can get optimum workability of concrete.

Abstract: HVFAC (High Volume Fly Ash Concrete) is an attractive construction material with cost benefit and reduced CO₂ emission. In this paper engineering properties such as compressive and shear strength are evaluated and their characteristics are investigated. For this work HVFAC with FA (Fly Ash) replacement ratio of 35% and 50% are prepared and strength (compressive, shear, and bond) are measured with basic parameters like elasticity and ultimate strain. Test results are compared with conventional predictions from Korea Structural Code and their applicabilities are evaluated. In bond strength and elasticity in HVFAC are evaluated to need reasonable coefficients for HVFAC design.

Abstract: Regional confined concrete is base on confined concrete. It is the theory and application of a new attempt and development on confined concrete. To apply it to the actual project, we need to research mechanical properties and establish constitutive relationship of regional confined concrete. According to the research, we had carried on a series of tests, founded the stress-strain constitutive model of regional confined concrete under single axial press. The accuracy of theoretical analysis were more fully verified , and a theoretical basis for the application was provided.