Applied Mechanics and Materials Vols. 174-177

Abstract: Admixture is a new material used for high-performance concrete. It is mainly used to improve the construction property and service performance and the durability of the concrete. At present, admixture is mainly made of a single component such as the slag, fly ash, silica fume, or mixed with a small amount of plaster. Different admixtures have different effects on the concrete and they have both advantages and disadvantages separately. Based on the principle of “Strength Synergistic Effect” of the composite materials, if the different kinds of admixtures are mixed into the concrete with suitable proportion, the advantages can be developed and the disadvantages will be avoided. In this study, the wide sources of admixtures such as slag, fly ash and limestone are used in the composite tests to develop a new kind of composite admixture which uses the slag as main raw material and has better performance.

Abstract: The concentration of chloride ion in concrete has been an important part of the study of reinforcement corrosion, while the microstructure of concrete on the concentration of chloride ions play an important role, in order to evaluate the sea sand for ordinary concrete and fly ash concrete microstructure andmineral composition, we use the 28 days of age in sea sand Mohr method for the determination of the different types of water-soluble chloride ion concentration to the chloride ion binding characteristics in the study of sea sand in concrete

Abstract: In order to improve the durability of concrete for mechane engineering, the experimental investigation of the preparation process condition of concrete have been reported.The effect of mix proportion design and chemical admixture on the strength of concrete are studied, the anti-permeability and anti-erosion by acid are analyzed. The results indicated that the addition of 1% water-reducing admixture and 3% organic Si waterproof (the precent of admixture and cement in mass) are useful to improve the mechanics property and durability of the concrete, the compressive strength after dipped in water 48 h enhance 100% , the permaebility grade enhance from P4 to P10, the erosion coefficient K decrease from 6.1% to 2.2% and the erosion degree R decrease from 57.5% to 32.8%, respectively, compare with that without dopant the water-reducing admixture. The results gained in this study are helpful for improving the the durability of the concrete and enlarge application the mechane engineering in rural areas.

Abstract: In order to obtain the intensity formula of recycled concrete, effects of crushed index of recycled aggregate, crushed index of natural aggregate and replacement rate of recycled aggregate on compressive strength of recycled concrete are discussed in this paper. Based on the results of recycled concrete with different replacement rate of recycled aggregate, the intensity formula of recycled concrete is proposed. It can provide references for engineering applications.

Abstract: In the paper, through analyzing large quantity of concrete mix proportions, a law existing in all concrete with different mix proportions and good workability is found, i.e., the volume ratios of sands to binder linearly increase with the increase of the volume ratios of water to binder. Meantime a table of the mass ratios of sands to sands and gravels is given based on numerous concrete mix proportions. According to the table and the linear equation between the volume ratios of sands to binder and the volume ratios of water to binder, a new method of mix proportion design of ordinary concrete - data analysis method is proposed.

Abstract: In this study, Melamine-methanol-formaldehyde-urea (MMFU) resin and the mixture of MMFU/boric acid/borax (MBB) were used as the modification solutions to impregnate wood from poplar plantation. The combustion performance of the wood before and after impregnation treatment was investigated by using the oxygen index apparatus and cone calorimeter. Results showed that the oxygen index of the MMFU and MBB treated wood both increased. Compared with the untreated wood, the MMFU and MBB treatment significantly delayed the ignition time and the appearance of peak value of the heat release rate (HRR) during the combustion. The MMFU and MBB treatment also reduced the heat release rate (HRR), total heat release (THR), mass loss rate (MLR), generation rate of carbon monoxide (GCO) as well as total smoke release (TSR) significantly. Both MMFU and MBB exhibited good effect of smoke suppression on wood, while MBB had better flame retardancy than MMFU. Boric acid/borax exerted excellent synergistic effect of fire resistance on MMFU.

Abstract: The paper presents the results of series of experimental studies on effects of the type and replacement ratio of fly ash to portland cement on durability of concrete. Specimens made from 28 mixes of fly ash concrete with water binder ratio of 38% to 60% and with replacement ratio of fly ash of 25% to 70% and 5 mixes of portland cement concrete with water cement ratio of 38% to 75% were tested for compressive strengths, drying shrinkage, carbonation and resistance to freezing and thawing. As a results, drying shringkage decreased with fly ash addition regardless of type and replacement ratio of fly ash. Carbonation increased with fly ash replacement ratio, and type 1 fly ash showed higher carbonation. Type 1 and tpye 2 fly ashes showed practically no change in durability factor after 300 cycles of freezing and thawing up to 55% replacement, while type 4 fly ash showed rapid reduction in durability factor up to 40% replacement ratio.

Abstract: Based on present situation that coal mining under buildings, water bodies and railways, and solid wastes mainly including coal waste, fly ash in coal mine of our country, optimization proportioning of paste filling material and hydration reaction mechanism is systematicaly researched combining with project practice of paste filling in Daizhuang Coal Mine, Zibo Mining Group. The result shows that: Proportioning design P10 can be used as the optimal proportion results, the rate of cementing material is that the proportion: fly ash: coal waste is 1:4:6, quantity concentration is 74%; Coal waste paste XRD diffraction patterns of different instar shows that its hydration products at different instar stage are mainly gelation of CH, Aft and C-S-H; Relative content of each material in hydration products is different at different instar stage; With scanning electron microscope a certin ettringite is producted after coal waste paste hydrated 8h, and content of C-S-H gelation and CH gelation is increased gradually; Hydration process of portland cement is speed up and the strength of paste is enhanced.

Abstract: the cement indusrry has a far-reaching effect on the economical development, and city is a layout poured by cement. The China cement industry is very promising, the choice between its industry layout and city economy development is an important content of the modern economy. In China, the cement industry not merely needs to be greatly develped, and much need to improve the structure and quality of the city. The city development needs the cement industry to scientifically adjust its industry layout, develop marketing channels, and improve the production service function. The industry development can promote regional economic harmonious order, and make progress in good way.

Abstract: The copper sleeve press-fit machine is a kind of device applied in automobile parts processing. The machine is used to press nine copper sleeves into a mold with nine holes. An automatic control system based on PLC is designed. CPU 224 of Siemens S7-200 series PLC is adopted as the core controller. The machine can be operated by either the human-machine interface or the pushbutton panel. There are all ten cylinders in this machine. The operation sequence and interlock protection of the ten cylinders are controlled by the PLC. In this system there are some necessary fault alarms and protective measures. The machine can be operated in manual mode or automatic mode. The press-fit machine is designed to operate simple with the high degree of automation and reliability, thereby saving work force and enhancing the efficiency of automobile parts production.