Advanced Materials Research Vols. 287-290

Abstract: The destructive expansion of CFBC ash is the bottleneck problem for its utilization in building materials. The addition of chemical substances and autoclave curing were used to inhibit the expansion in the paper. The results show that the addition of 1% CaCl₂ or 1% Na₂CO₃ can decrease the 28 d linear expansion ratio of CFBC ash-water mortars by about 19%, with no disadvantage influence on the compressive strength. Moreover, the linear expansion ratio of CFBC ash-clinker-water pastes was below 5×10^-4 after autoclave curing. The work confirms that the expansion of CFBC ash can be inhibited effectively by the way of autoclave curing.

Abstract: This report mainly evaluated the pavement performance of natural asphalt from Albania. Firstly, base asphalts were processed with natural asphalt by “wet method” modification technique to obtain modified asphalt; and mixture are produced with these modified asphalt binders, and then high temperature performance and moisture stability properties are evaluated by some standard methods. Analysis shows that this natural asphalt can remarkably improve the high temperature and moisture stabilities of asphalt mixture, and own cost-effective advantage.

Abstract: In the present work, Zn-1.0Cu-0.2Ti alloy was prepared by melt casting and extruding processes. High temperature creep property of the alloy was determined using electronic creep relaxation testing machine. Microstructures of the alloy before and after creep test were observed and its high temperature creep mechanism was discussed. The results show that the steady-state creep rate of the alloy increases with temperature and stress. The logarithm of steady-state creep rate (ln) shows a linearity relationship with the logarithm of the stress (lnσ) and reciprocal of temperature (1/T). The stress exponent and apparent activation energy for creep have been determined to be 5.10 and 83.7 kJ/mol, separately. The predominant mechanism is mainly self-diffusional creep. The second phases on the grain boundary can block the slip of grain boundary and dislocation motion which can improve creep resistance of the alloy.

Abstract: Numerical simulation is a good method for studying some academic problems in the engineering. Laboratory triaxial tests of composite soil were used widely in order to understand the stress-strain relationship. But the deformation of composite soil in laboratory triaxial tests is difficult to measure in some situation. Numerical simulation on laboratory triaxial test of composite soil with roots is carried out to see how the deformation of composite soil developed under the pressure on the specimen. Drucker-Prager constitutive model was used in the numerical simulation of finite element analysis. The results show that the numerical simulation of finite element method using Drucker-Prager constitutive model is suitable for studying the deformation development of composite soil with roots. The research results are important for understanding the deformation development of laboratory triaxial test of composite soil with roots.

Abstract: This study is mainly focused on the design and application of pervious concrete material to pavement and growing plant. The test results show: 1. Addition of fine aggregate obtains better binder quality. 2. Both small aggregate size and good aggregate gradation improve strength, but reduce void ratio and permeability. 3. A data bank of the relationship of the strength, the void ratio and the permeability of pervious concrete was built. 4. A practice case study of pavement demonstrates excellent permeability comparing to the local code and good quality as well as grass growing normally.

Abstract: Investigation on the continuous dehydration process of calcium silicate hydrate with C/S 1.5 during heating in the air was carried out. Results showed that the heating at 200°C of C-S-H resulted in decreasing basal spacing from 1.2 nm to 1.0 nm, and the basal spacing disappeared as the temperature raised to 400°C. Small amount of the dehydrated calcium silicate hydrate, portlandite and calcite were detectable in the heated sample at 400°C. The phases in the samples heated at 500°C and 650°C are β-C₂S, quartz, and calcite. At 800°C and 900°C, α′-C₂S, β-C₂S, and quartz are main phases in the heated sample.

Abstract: Light Emitting Diode (LED) has been already familiar that is used as lighting sources of general electronic devices and various displays. LED has many advantages such as long life, low power consumption and high reliability. In the future, as alternative to fluorescent lighting, it is sure that LED in lighting products is expected to receive much attention. However, the components related with advanced LED packages or modules have been issued on the heat from LED chip. And the LED chip is still being developed to the high power devices which are generating more heat. In this study, we investigated the variation of thermal resistance in LED modules embedded with thermal via. Through the analysis of thermal resistance with various test vehicles, we could obtain the concrete relationship between thermal resistance and structure of thermal via.

Abstract: Recent consideration has been given to use of GGBFS as separate cementitious material mixed along with Portland cement in production of concrete. Problems are frequently encountered in producing good-quality concrete specially slag cement concrete in hot climates.Curing problems are exaggerated when concreting in hot weather, as a result of both higher concrete temperatures and increased rate of evaporation from the fresh mix. The disadvantage of GGBFS concretes is that they proved to be more sensitive to poor curing than OPC Therefore, special care must be taken when using this type of concrete, especially on site, where the working conditions and the application of curing are not as easy to control as in the laboratory concrete. The purpose of this paper is investigation and evaluation strength loss in slag cement concrete in poor curing situation. To carry out this aim, 72 cube specimens with three different proportion of slag are made and cured in two different conditions. And result of compressive tests compared together to determine susceptibility of GGBFS concrete in hot-dry condition.

Abstract: Subgrade diseases are exposed more and more serious with raising speed of existing railway in wide range. Dynamic numerical simulation had been done to analyze the effect of CFG-pile caps and cushion in composite foundation with CFG-pile in low embankment of Beijing-Shanghai high-speed railway. Distribution rules of dynamic displacement and dynamic stress of the subgrade surface and ground surface on the cross section, attenuation rules of dynamic response and dynamic stress ratio between pile and soil on the vertical section were studied. It shows that the dynamic stress of pile and soil generally attenuates in depth and attenuation of dynamic stress ratio between pile and soil mostly concentrates in the scope of 10m beneath the ground and dynamic stress caused by train load is undertaken by the pile. Moreover the scheme of CFG-pile with no pile caps and rigid cushion scheme is superior to that of pile caps and flexible cushion scheme for enhancing dynamic stability and reducing dynamic displacement and stress in low embankment. It will be instructive to control design and construction for the low embankment in Beijing-Shanghai high-speed railway.

Abstract: The effect of AgSbO₃ on the piezoelectric properties of (K_0.5Na_0.5)_0.95Li_0.05NbO₃ was examined. The AgSbO₃ doped KNLN samples sintered at 1050°C showed the maximum values of the sintering density of 4.56 g/cm³ compared to un-doped KNLN samples sintered at same temperature with 4.25 g/cm³. Moreover, the addition of AgSbO₃ enhanced the piezoelectric and dielectric properties. Piezoelectric constant (d₃₃), the planar electromechanical coupling factor (k_p) and the relative dielectric permittivity (K₃₃^T) increased up to 230pC/N, 43.5%, 1080, respectively, with addition of AgSbO₃.