Advanced Materials Research Vols. 881-883

Abstract: By means of grafting polymerization, cross-linked starch-g-polyacrylamide (starch-g-PAM) was prepared and used to adsorb methylene blue (MB). Adsorption isotherm and kinetic of the sorption process were studied. The experimental results demonstrated that the prepared starch-g-PAM was an effective adsorbent for removal of MB from aqueous solution. The adsorption of MB by starch-g-PAM was Freundlich type, and the adsorption equation was caculated to be . Furthermore, the adsorption kinetics analysis demonstrated that the adsorption process followed the pseudo-second-order model.

Abstract: The environmentally friendly composite of poly (vinyl alcohol) (PVA) and shortcut grass were prepared by hot-pressing method. First, dry grass was cut into 1.5 cm long segments. Then, shortcut grass was mixed with PVA by using water as medium. The mixed uniformly raw materials were hot-pressed at different temperatures for different times. The effects of raw material ratio, hot-pressing temperature and hot-pressing temperature on composites performance were studied. Results showed that composites tensile strength increases with the increase of PVA content. Tensile strength reaches 3.59 MPa at 50% of PVA content. The tensile fracture stretch increases with PVA content and reaches 25.28% when PVA content is 50%. The tensile strength first increases and then decreases with the increase of hot-pressing temperature and hot-pressing temperature. The hardness of composite is uneven. Hardness at 20% of PVA content is lower slightly than that at other PVA contents.

Abstract: Unfrozen water content has an important influence on the physical and mechanical properties of frozen soil. Little research has been done on unfrozen water content of permafrost in the Northeast Region, China, so the experimental investigation was performed on Mohe permafrost (4 kinds of samples were taken from 4 kinds of undisturbed frozen soil) based on NMR method, and the relationship and between frozen temperatures (-1°C, -4°C, -7°C, -11°C, -14°C, -16°C) and unfrozen water content was obtained. The test results indicate that, Unfrozen water content decreased with the reduction of frozen temperature of permafrost and there was a power function relationship between unfrozen water content and frozen temperature. The unfrozen water content reduction of No.3 sample was the slowest, because it had the lowest water content and the least frost-heave and thawed amount. It also can be attained that ice content of Mohe permafrost became more and more, but bound water and free water content got less and less while frozen temperature fell continuously.

Abstract: The sludge, dredging silt and other materials prepared by mixing the ceramic, studying the effects of different sludge ratio, sintering temperature, the amount of excess sludge moisture content on ceramic, pile density, ignition loss rate. Produced ceramic concrete specimens tested by experiment and standard ceramic concrete specimens concrete specimen strength and thermal conductivity. Test specimen obtained ceramic concrete compressive strength of 13.57MPa, mixing concrete block compressive strength of 13.96MPa; gravel concrete specimens of thermal conductivity 0.394, ceramic concrete specimens thermal conductivity of 0.387. The results show that adding the ceramic concrete, ceramic concrete strength of certain decline, but the performance is enhanced thermal insulation, thermal insulation properties can greatly enhance it.

Abstract: Using all components of waste concrete with limestone coarse aggregates as the raw materials produces recycling cement. Recycling cement clinker will be produced in this way by sintering waste concrete and a certain amount of accessory materials. It is a technical route of protection environment, resource conservation and sustainable development.

Abstract: The magnetic performance of steel slag is special because it has a high content of Fe₂O₃. In this study, the difference of chemical compositions, mineral compositions, and particle size distributions between the two parts of steel slag by magnetic separation was investigated. The results show that the difference of chemical compositions especially the main oxide contents between the two parts of steel slag by magnetic separation is very small. And the difference of mineral compositions between the two parts of steel slag by magnetic separation is also very small. However, the particle size distributions of the two parts of steel slag by magnetic separation may differ from each other when steel slag contains many coarse particles.

Abstract: Chloride ion penetrability of recycled aggregate concrete is one of durability, but it is less on research at present. It simulates resist function which recycled aggregate concrete exists in chlorine ion environment, Results on comparing with natural aggregate concrete will provide reference to study on durability of recycled aggregate concrete.

Abstract: large thickness of λ/4 type absorber has been an important issue, which affects its application and urges to address. In this paper, λ/4 Type absorber made of carbon fiber membrane, instead of resistive film, and Gypsum board. Its designed for thinning and we took Simulation analysis and experimental testing for it. Results show that, while carbon fiber membrane with a length of 2mm and content of 2.8%, λ/4 type gypsum composite absorber has better absorbing in S-band. Compared with the resistive film, absorber achieved thinning of 10.6%.

Abstract: In order to increase freeze-salt scaling resistance of concrete, effect of water-binder ratio, fly ash, slag and silica fume on freeze-salt scaling resistance are researched according to the CDF method. The results show that the scaled mass and the dynamic modulus of elasticity loss rate of the concrete are reduced with decreasement of water-binder ratio. When mineral admixture compound is added into concrete the scaled mass and the dynamic modulus of elasticity loss rate are also reduced. Compared with fly ash and slag the trend is more obvious as result of fume and slag added. The scaled mass and the loss rate of dynamic elasticity modulus are slightly reduced with decreasement of fly ash and slag. But the scaled mass and the loss rate of dynamic elasticity modulus are obviously reduced with increasement of silica fume and slag.

Abstract: According to the principle of electromagnetic wave absorption, functionally reforming thermal insulating materials for building, through designing and theoretically simulating of the λ/4 model, the article has successfully prepared EPS composite gypsum boards for electromagnetic wave absorption. The result shows that, a maximum absorption of-18.7dB at 3GHz and 85% of bandwidth below-10dB was achieved under following conditions: using 380Ω/□ resistive film, specimen thickness of 1.50cm. However, by using phase modulation membrane (PMM),it achieved a maximum absorption of-20dB and 100% of bandwidth below-10dB. This new composite materials can be used for electromagnetic interference protection for WLAN and indoor electromagnetic radiation pollution control.