Advanced Materials Research Vols. 287-290

Abstract: The mechanism of melt treatment improving the glass forming ability (GFA) and thermal stability of the Al_84.5Ni_5.5Y₁₀ (in atomic percentage) alloy was studied. An yttrium-rich metastable high-melting-temperature-phase is found to be responsible for the deterioration of GFA because it induces the heterogeneous nucleation of the crystals in the solidification process. It can be eliminated through melt treatment as adopted in this paper, resulting in stabilizing the thermal stability of the undercooled melt and enhancing the GFA of the investigated alloy with higher thermal stability for the resultant amorphous phase.

Abstract: Low tensile strength and high brittleness are the inherent defects of cement-based composites. So improving the toughness effectively is an urgent need for developing high-performance cement materials. The aim of this study is to study the toughening effect by mixing CaCO₃ whiskers and polypropylene fibers in cement mortar. The results showed that CaCO₃ whiskers could increase the split tensile strength of cement mortar of 28d age by 26.2% at maximum with the whisker content of 10wt.%; when CaCO₃ whiskers content was 10wt.% and polypropylene fibers content was 0.20vol.%, the split tensile strength of cement mortar was increased by 21.1% at 28d age; when the fiber length was 19mm, the composite toughening effect of whiskers and fibers was more effective. The toughening mechanisms of CaCO₃ whiskers and polypropylene fibers in cement mortar were also discussed.

Abstract: In this paper, recycled PE was added directly to the asphalt mixture to prepare high modulus asphalt mixture. To study the influence of the dosage and molecular weight of recycled PE on the performance of asphalt mixture, three kinds of recycled PE with different molecular weight and three asphalt binders (Conventional, SBS Modified and PE Modified) were used to prepare eight kinds of asphalt mixture. Various tests, including dynamic modulus, wheel tracking and Lottman test, were conducted to evaluate the performance of them. The results showed that 1) the dynamic modulus of asphalt mixture modified by recycled PE is higher than the normal mixture and mixture prepared with SBS modified asphalt binder; 2) adding recycled PE directly into the asphalt mixture during mixing is more effective than preparing asphalt mixture with PE modified asphalt binder in making high modulus asphalt mixture; 3) the recycled PE used to produce high modulus asphalt mixture should have certain big molecular weight, more than 27,000, and the dosage of recycled PE should be no less than 0.4% of the total weight of asphalt mixture. The performance tests indicted the good high temperature deformation resistance property of asphalt mixture modified by recycled PE.

Abstract: As reinforcement of goaf filling needs, filling material mined area become the focus of research and development. This study used PO42.5 Portland cement, fly ash, coal gangue, preparation meets the requirements of good performance out of the strength of pumping gangue filler.

Abstract: The objective of this article is to provide a paving project for steel bridge deck based on a new composite bonding system of Cement/emulsified-Asphalt/Epoxy resin (CAE). Reinforced both by Epoxy and emulsified-Asphalt, the cement-based material has reflected good performances, especially rutting deformation at high temperature and adhesive strength with steel blocks, which should be satisfied to long-span steel bridge deck.

Abstract: The grinding dynamics of phosphorous slag has been studied by vibration mill, and relational grinding rate equations of phosphorous slag have been derived. The results show that specific surface area,characteristic diameter and uniformity coefficientof ground phosphorous slag powder are in lineal relation to logarithmic or log-log-arithmic of grinding time. When grinding time is from 0 to 30 minutes, grinding efficiency is higher and specific surface area has higher growth rate

Abstract: Using PCER (post-crack energy ratio) method and plain concrete specimen as reference, the flexural toughness enhancing ability of propylene spinning fiber, propylene monofilament fiber and end-deformed steel fiber was studied. Experiment results show that under the common engineering dosage, the flexural toughness enhancing ability of end-deformed steel fiber is far more outstanding than propylene fibers, and comparing with each other, the flexural toughness enhancing ability of propylene spinning fiber is better than propylene monofilament fiber. As far as one type of fiber is concerned, under the same dosage, along with the enhancement of concrete strength grade, the flexural toughness enhancing ability tends to decrease. Meanwhile, along with enhancement of curing age, the flexural toughness enhancing ability tends to decrease also.

Abstract: Using PCER (post-crack energy ratio) method, the influence of strength grade and curing age on flexural toughness of plain concrete were analyzed. Results show that along with the increase of strength grade and curing age, the flexural toughness of plain concrete decrease; and along with the increase of the K value used in the calculating equation, the flexural toughness of plain concrete decrease too. Meanwhile, the changing tendency of PCER value along with the K value manifests that when evaluating the flexural toughness of different quality concrete, the same K value should be used.

Abstract: There is much difference among the amorphous substances of different coal ashes, the important basis for their utilization. The micromorphology and content of the amorphous substances were measured by scanning electron microscopy (SEM) and chemical method respectively, and the 28d compressive strength ratio was also used to characterize their contribution to the cement-coal ashes system. The results show that the amorphous substances of BFBC/CFBC ashes are irregular and loose textured, which are significantly different from those of PC fly ashes that are spherical and compact. The content and the pozzolanic activity of the amorphous substance of BFBC ashes are greater than that of PC fly ashes.

Abstract: Synthetic C–S–H and C-A-S-H samples with different Ca/Si molar ratios (1.0 and 1.5) were prepared by precipitation from solution. The effects of incorporations of aluminum ion into C-S-H gels on their microstructure were studied by applying Fourier Transform Infrared Spectroscopy (FTIR), BET nitrogen adsorption and scanning electron microscopy (SEM). Results show that in FTIR spectra, peaks nearing 970 cm^-1 and 450 cm^-1 wave number change obviously with the substitution of Al³⁺ into C/S1.0 C-S-H. In BET diagram, it also can be found that the substitution of Al³⁺ into C/S1.0 C-S-H lower the specific surface area. Furthermore, SEM graphs also show that the morphology change in C/S=1.0 C-S-H after the substitution of aluminum ion. However, little difference can be found in FTIR spectra and BET diagrams after Al³⁺ doped into C/S1.5 C-S-H. So, it can be concluded that the effects of the substitution of aluminum ion on the structure and morphology of C-S-H are affected by Ca/Si molar ratio