Applied Mechanics and Materials Vols. 174-177

Abstract: As a lot about the erosion of sulfate on cement specimens point to the erosion of the hydrated calcium silicate gel C-S-H research. In order to get actual calcium silicate hydrate gel, which can be used to adapt to the current needs of research on hydrated calcium silicate gel C-S-H, it is necessary to explore a variety of methods of preparing hydrated calcium silicate gel C-S-H. The hydrated calcium silicate gel prepared through very methods, such as liquid-phase reaction method, calcium silicate (C3S and C2S) hydration and extraction of hardened cement paste, is identified and compared. It is found that the hydrated calcium silicate gel C-S-H extracted from hardened cement paste is more in line with the actual situation and meeting the needs of a variety of studies.

Abstract: The rheological phenomenon of concrete materials, also termed as creep, is one of very important properties of concrete. Excessive deformation caused by creep does more detrimental effects on prestressed concrete structures than otherwise. Even though some investigations had been conducted on the normal concrete mixtures by the researchers and engineers all over the world, and the conclusions and the creep prediction models based on those investigations were developed, their effectiveness to be extended to all the concrete mixtures is very limited due primarily to the susceptibility of the creep property of concrete to the variation of the properties of aggregate, cement, water to cementitious materials ratio and their proportions. Especially for prestress concrete, creep induced prestress loss puts severe threat on the safety and durability of prestressed structures. Thus, in order to thoroughly understand the creep characteristics of the typical concrete mixtures used in Florida, this project was carried out by University of Florida and Florida Department of Transportation. The investigation found out that the creep strains of the concretes with different types of coarse aggregates at 91 days are very close, while the differences of creep coefficients of the concretes with different aggregates are fairly significant.

Abstract: This thesis is to introduce the presentation and application of wood, the traditional building material, as one of the epidermis materials of contemporary cultural architectures. It will clarify materials types as wood architecture epidermis materials and the creating tendency of interface presentation, as well as its treatments and protections in architecture application. This intends to provide technical and theoretical supports to methods of emergence of appearance type of new wood structure architecture material.

Abstract: In order to arrange the limited test for considering the influence of high additive fly ash firebrick to different element comprehensively and effectively, the authors arrange the orthogonal test and put forward the best proportion scheme and propose industrial production properly through the systematic analysis of the test results.

Abstract: Abstract: The concrete as a porous cement-based material is widely used in practice. The analysis of the basic reason why the drying shrinkage stress develops in concrete at early age is made by using the principal of the equilibrium between capillary water repulsive force and molecular attracting force. The model for computing the drying shrinkage stress for nonbinding concrete is presented by relating the capillary water pressure to relative humidity. Based on it ,the model for concrete fully restrained is given. The measurement of the drying shrinkage stress and depth of cracks caused by the drying shrinkage stress is made by using translation symmetric theorem and adopting dog-shaped specimens, and the analysis of changes in depth of cracks over time for two kinds of specimens is made. using the method of comparison ,the comparison of the gradient of the drying shrinkage stress for two kinds of specimens is made ,and it comes to the conclusion that the median drying shrinkage stress in the concrete fully restrained is higher in value by 1MPa compared to the drying shrinkage stress in non-restrained concrete

Abstract: This paper studies the early mechanical properties of artificial sand concrete, we found by comparison with natural sand concrete that the slump of artificial sand concrete were increased by 85%, and the strength 0f 16h and 1d and3d were increased by 23.4% and 20% and 11%. Therefore, artificial sand can significantly improve the workability of concrete mix, improve the early strength of concrete. It has guidance significance to the early strength of concrete engineering.

Abstract: Characteristics and constraint mechanism of concrete confined by ties,concrete filled steel tube,FRP-strengthened concrete were summed up in this paper,and unified bearing capacity model for confined concrete was also introduced,then several new kinds of confined concrete forms were outlined,finally the development and application of confined concrete were prospected.

Abstract: The influences of particle sizes of asphalt emulsion on the storage stability of emulsion and properties of cement and asphalt mortar were studied. Results indicated that, the storage stability was improved with the decrease of particle size, while the emulsion stability was not improved significantly when the particle size was less than 3μm; the fluidity was improved while the separation rate was increased with the decrease of particle size; the early strength of CA mortar was increased when prepared with the emulsion with larger particle size; while the emulsion with smaller particle size was benefit to the late strength development of CA mortar.

Abstract: This thesis first analyzes the necessity for the application of limestone powder produced in Lime Ridge from Xixia County, Henan Province. It also tests the concrete performance with different composition materials and does research on the influence of limestone powder on concrete strength by adding limestone powder instead of fly ash in fly ash concrete. It then finds out the reasonable volume of limestone powder to meet the concrete’s performance, in order to guarantee the scientific and effective use of limestone powder in concrete engineering.

Abstract: The study applies Computed Tomography technology to probe into the porous asphalt concrete and air voids content, and at the same time, try to qualify accessible voids and closed voids and to use the result to evaluate the performance of porous asphalt concrete. The nominal maximum aggregate of this study is 19.0mm. In order to adjust the image of the gray threshold, the void of PAC specimen was obtained by cut-and-try method with the mix design. After scanning through the PAC specimen, the self-innovated software is used to calculate the Va(%), accessible voids and closed voids. After careful calculation, it showed that the accessible voids are about 20.3%, and the closed voids are about 1.15%. Base on the study, it could analyze the effect of pore clogging in PAC with improved the durability and lifetime.