Advanced Materials Research Vols. 1065-1069

Abstract: Reduction electric furnace slag, quartz sand and soapstone were used as the raw materials for preparation of glass-ceramics according to their compositions and characteristics. Differential thermal analysis, X-ray diffraction, scanning electron microscopy were used to investigate the crystallization mechanism, microstructure and main mechanical properties of slag glass-ceramics with different mass ratios of MgO/Al₂O₃. The exothermic peaks of the DTA curves shift to higher temperature with the decrease of MgO/Al₂O₃ ratio. And along with the decreasing of the MgO/Al₂O₃, the crystallization of the glass-ceramics also decreased. The bending strength can reach 153.09MPa when the MgO/Al₂O₃ ratio is 3.03.

Abstract: For the purpose of research on behavior of argillaceous dolomite suffering from frequent cryogenic freezing weather in Guizhou region, the rock was processed into cylinder samples (diameter 50mm&height 100mm). Using BCD-218 cryogenic digital control equipment, in saturated state, the samples were frozen (-20°C) and thawed (20°C), each 12 hours for one cycle, total 30 times. Then, Longitudinal wave velocity (LWV), macroscale and mass varying with freezing-thawing cycles were respectively tested by RS-ST01C nonmetal supersonic test meter, vernier caliper (0.02mm), APT457A electronic balance (0.01g). Also, appearance characteristics were observed constantly. Lastly, the micro reason for changes in macro parameters of the rock was explained. The results show that the freezing-thawing deterioration form of argillaceous dolomite is spallation mode, and LWV decreases obviously with the increase of freezing-thawing cycles (FTC),maximum drop of 14.8%,while mass has a small increase, maximum change rate of 0.5%. Macroscopic properties are obviously affected by freezing and thawing cycles. Key words: argillaceous dolomite, freezing-thawing cycles, supersonic detection, damage characteristics

Abstract: Performance tests are conducted on pervious concrete mixed with Polypropylene Split Fiber (PPSF), in which basic indexes such as compressive strength, splitting strength, flexural strength, porosity, permeability coefficient are measured. Results indicate: mixed with certain amount of PPSF in ordinary pervious concrete is feasible, and during mixing PPSF is split into uniformly distributed monofilament fiber without occurrence of agglomeration or rustiness; incorporating 3kg PPSF in 1m³ pervious concrete is proper, under which compared with the ordinary pervious concrete, both porosity and permeability coefficient are decreased, but application requirements are still met, while strength is increased obviously; the pervious concrete mixed with PPSF can be used in ordinary light traffic pavements.

Abstract: In this article, the flexural strength of combined aggregate concrete with four kinds of water-cement ratio (0.3,0.35.0.4, 0.45), and six ceramsite replace rate (0%, 20%, 40%, 60%, 80%, 60%) are studied with comprehensive test method. Experiment shows that the ceramsite replace rate of combined aggregate has greater influence on the flexural strength than the water-cement ratio. The flexural strength increases with the increasing of compressive strength, and the formula of the flexural strength and compressive strength of combined aggregate concrete is given.

Abstract: In this paper, the flexural performance of steel fiber combine aggregate concrete under the different factor (water cement ratio, quantity of light aggregate, steel fiber volume fraction, and the types of steel fiber) is studied. And the orthogonal experiment method is adopted. From the experiments, it could be found that the most important factor affecting the flexural strength is the steel fiber volume fraction, and then the types of steel fiber, the water cement ratio, and the quantity of light aggregate in the order. With the increasing of the steel fiber volume fraction, the flexural strength of concrete improves obviously. On the basis of the experiment, the relationship formula of flexural strength and the cube compressive strength is given.

Abstract: Sulphur binders originate by burnout of calcium sulphate dihydrate at different temperatures. All types are classified in air mortars therefore they can solidify, harden and remain stable only on air.

Abstract: Elbow as common components in the gas pipeline fails easily to natural gas carrying solid particle erosion in the process of practical work. From the viewpoint of hydromechanics, the paper analyses the flow field distribution of manifold pressure and gas-solid trajectory by using the Gambit model and Fluent software in view of the right-angle elbow and numerical simulation of the adjacent manifold. The result obtains the situation about the manifold inner wall by the solid particle erosion wear. The simulation results show more intuitively the elbow, the most prone to erosion part in the manifold adjacent area and shape in erosion. Meanwhile, the paper analyses the factors affecting the occurrence and development of erosion.

Abstract: Fire-proof paint thickness is of importance to steel structure fire safety, and the common programme iteratively solves its heat conduction equation in fire-insistence test, while by dimensional analysis in the equation, this paper constructs a function of steel structure section-material grouped parameter, and also a similarity form is employed to form a relationship between any two different transient fires, then solves the grouped parameters in two other transient fires. Parameter comparisons among these 3 fires conclude: with the same fire time, fire-proof paint and size, fire-proof paint thickness is necessary to be the biggest in fire-insistence test, and smaller in site fire, and the smallest in t-square fire. The key factor to decide the thickness is surface temperature outside fire-paint. The common programme is with some redundance, and more reasonable guard should add to the steel structure in t-square fire. The foregoing analysis to fire-proof paint thickness by the function of steel structure section-material grouped parameter and the similarity form between any two different transient fires, broadens the common programme to any transient fires.

Abstract: Ce_0.8Pr_0.2–xNd_xO_2-δ(x = 0.02, 0.05, 0.1) solid solutions were synthesized by the sol-gel method. The XRD results show that all powders calcined at 800 °C are crystallized in a single cubic fluorite structure. The average grain sizes are between 20 nm and 25 nm. The Raman spectra analysis reveals that the solid solution Ce_0.8Pr_0.2–xNd_xO_2-δ has a cubic fluorite structure with oxygen vacancies. The oxygen vacancy concentration is increased by doping Nd in Ce_0.8Pr_0.2–xNd_xO_2-δ. Impedance spectra shows that the conductivity of rare earth co-doped ceria Ce_0.8Pr_0.18Nd_0.02O_2-δ is higher than that of single rare earth doped ceria Ce_0.83Sm_0.17O_2−y. The results also show that Ce_0.8Pr_0.18Nd_0.02O_2-δ possess maximum conductivity. At 600 °C, the conductivity is 1.85×10^-2S/cm, which is assigned to the higher oxygen vacancy concentration and the hopping electron transition of small polarons in the sample Ce_0.8Pr_0.18Nd_0.02O_2-δ.

Abstract: In recent years, the photocatalytic properties of nano TiO₂ (nanotitanium dioxide) is one of today’s hottest issues of environmentally friendly materials, medical materials and building materials fields. In this paper, we present the latest research on nanotitanium dioxide to be used in the field of building materials. Based on the history of the photocatalytic properties of nanotitanium dioxide, the application of nanotitanium dioxide in photocatalytic concrete, photocatalytic ceramics, functional coatings and materials in the field of self-cleaning glass has been analyzed. Finally, further research will focus on nanotitanium dioxide used in the field of building materials.