Applied Mechanics and Materials Vols. 357-360

Abstract: In order to further study the impact crushing mechanism of cement clinker, the impact experiment has been carried out at different impact angles. Impact crushing curves, acoustic emission signal and peak impact force and impact fracture morphology have been systematically studied. It is shown that each impact crushing curve includes an inertia peak and an actual impact peak. AE signal directly reflects the crack initiation and propagation during the process of impact experiment. With the increase of impact angle, the average value of peak impact force decreases. The peak impact force value reaches the minimum at 75 °. The experiment results will offer a successful alternative to the low – energy grinding of cement clinker.

Abstract: The height of vertical pier retaining wall is relatively larger in regions with great height of water. As the retaining wall becomes higher, the cross-sectional area of ordinary gravity pier structure becomes larger and foundation strength needs to be larger, thus there are some restrictions for traditional structure form. This research focuses on new structure forms of high concrete retaining wall and its optimization design for piers in regions with great height of water. This study establishes a nonlinear constrained mathematical model of pier high retaining wall structures. The objective function is cross-sectional area of the pier retaining wall which is restricted by the stability, bearing capacity of foundation and strength of cross-section of retaining wall. This model is solved by fmincon function from Matlab and the results present an economically reasonable cross-section form. This new selection is greatly significant to improve the stability of high concrete retaining wall and reduce the project cost. The new structure is successfully used in a port of Huaihe River and it can be a solution to pier structure selection problem in regions with great height of water in the future.

Abstract: In this paper, the rule of index weight is determined by analyzing the existing rules of life assessment for concrete. Based on fuzzy decision making of binary comparison, the weight of different factor taking effect in complicated environment can be analyzed. With known effects of each factor, the classification and score of concrete durability can be made. Thus the assessment of concrete durability in complicated environment can be modeled. The model is used to predict the service life of concrete and provide optimize mix proportion design.

Abstract: High-effect concrete of C60 was made up by local cement of po42.5 and polycarboxy late super plasticizer through activity of the slag powder and the fly ash. Orthogonal test researches show that C60 adding higher activity index can be made, and it was characteristics of low cost, materials convenience and fine durableness.

Abstract: The determination of concrete strength in situ plays a critical role in the quality of structural engineering analysis and acceptance. The strength is usually determined through pure tension tests, like the common pull off test. However, in most applications, the shear strength is more interested. A novel approach, that is instrumented double-hole shear test, was presented for determining the strength of concrete. Drill two holes at two sides of measured concrete area, and the indentor is loaded from one hole in giving shear failure. Then, determine the strength of concrete according to the maximum shear stress when its destroyed. Conduct the double-hole shear test and the cubic compresion strength test on the different strength of concrete specimens and establish the correlations between the two strength values. The results show that the ratio of the two strength values is in the range from 0.085 to 0.351, which depends on the concrete strength.And the two strength values have a good linear relationship so it can provide a new method which can easily and reliably determine the concrete strength in situ.

Abstract: The most important mechanism of deterioration occurring in concrete in the cold regions are chloride ingress and freeze-thaw cycles. In this paper, the process of chloride ingress into concrete exposed to freeze-thaw cycles is experimentally researched. From the experimental results, it appears that freeze-thaw cycles make the effective diffusion coefficient become bigger. As w/c ratio increasing and fly ash content decreasing, the effective diffusion coefficient increases. The concentration of salt solution has little influence on the effective diffusion coefficient of concrete.

Abstract: Research on stability problem, has put forward the famous bar under axial pressure formula from the middle of the eighteenth Century Euler critical force, more than 200 years, the elastic range but recognize that Euler's formula is only suitable for the material, but it took more than a hundred years. Study on the inelastic critical load of column, double modulus theory and the tangent modulus theory. These theories are starting from the ideal straight rod, and practical bar called " defects exist various accidental eccentricity " ( such as physical and geometrical aspects of the initial deflection rod, pressure asymmetry in aspects of material unevenness, residual stress) is not consistent. Thus the utility pressure bar, should according to the eccentric pressing rod is considered more practical.

Abstract: During the construction process of massive concrete, the construction must forecast and control the temperature forming of massive concrete in order to avoid the temperature crack owing to the thermal stress caused by the concrete heat. The discussion on the concept of grey system interval and grey number predication applies to the temperature rise prediction of massive concrete in the construction process. The previous temperature rise data is divided into the white part and grey part based on real numbers. And the interval grey number forecast computing models are established, so we can finish the temperature rise prediction during construction process. The forecasting results of case show that, this model has fast convergence and remarkable precision. Then, it is possible to realize the accurate temperature rise prediction of massive concrete.

Abstract: The change law of gel time of calcium carbonate-acid water glass grouting material with the content of calcium carbonate is researched in this paper. But the gel time does not increase evenly with reduction calcium carbonic reducing. It increases suddenly because there is sudden exceeding range with the solution pH value increasing. Meanwhile, the change relation of strength of pure gelation with suitable gel time and time is measured. Firming sand strength experiment is conducted by the better mixture ratio. The strength of pure gelation body increases with the time and the content of calcium carbonate increasing. It is closely related with the reaction mechanism of calcium carbonate-acid water glass. The active Ca²⁺ in this system can react with a series of silicate ion to form silicate precipitate which is filled with colloid and forming skeletonation. And the correlation between firming sand strength and the calcium carbonic acid content is non-significant. Finally, the contrast test of the water glass-glyoxal is done, which is the preparation for the subsequent engineering application.

Abstract: From 1980s, stainless steel has been widely used as a kind of sculpture material in China, because there is a large need of quickly constructed, huge-sized modern sculptures during rapid urbanization. But the problems of excessive popularization of art crafts and disappreciation of art emerged. Only through the comprehensive function of improving supervision, promoting art and technique level as well as popularizing social art education, will stainless steel development be ensured in future Chinese urban sculptures.