Applied Mechanics and Materials Vols. 99-100

Abstract: This paper establishes the prestressed wind power tower model and studies on large wind power tower structure concept optimization for wind power development trends and problems. The results show that, no matter how weight of steel tower, or the amount of base concrete earthwork, the prestressed wind power tower has the potential to reduce the construction cost with good prospects. And the conclusions can provide a useful reference for the wind power constructions.

Abstract: U(VI) of the acid leaching uranium-containing wastewater was adsorbed by modified CMC polymer. The result showed that the grafting rate was found to be 68% on the conditions, i.e. temperature 70~80°C, monomers quality concentration 30~35%, Carboxy methyl cellulose and acrylic acid mass ratio of 10:2.5, contact time 3.5~4h. The uranium adsorption capacity of modified CMC was studied and compared with unmodified CMC. The results also revealed that U(VI) ions uptake rate was rather slow, with 75% of the total amount occurring in the first 60min for Modified CMC Polymer. the optimum experimental conditions were CMC quality concentration 0.10g/L, temperature 25°C, pH 5.0, contact time 100min; under the optimal conditions, the removal of U(VI) was 97.1% and 21% higher than unmodified CMC.

Abstract: Solidified dredged materials as environment-friendly materials in construction domain are increasingly popular because of their better mechanical performance and low pollution. Based on the physical characteristic of dredged marine sediments, a series of tests, such as unconfined compressive strength test and tensile strength test, were performed to explore the mechanical properties of cement/lime-fly ash treated sediments for the beneficial use in road construction. Finally, the reinforcement mechanism of solidified sediments was explored by SEM tests from the point of view of the formation of CSH phases and the change in microstructure.

Abstract: Comb-shaped hyper-branched polycarboxylate polymers, both water-reducing-type admixtures (applied in cement, symbol of JS) and slump-retaining-type admixtures (applied in cement, symbol of BT), were prepared, and their adsorption characteristics with SO42- ions were studied by conductivity loss experiments. The results indicated that both JS and BT generate electrical conductivity losses in Na2SO4 aqueous solutions, suggesting that there was some interaction adsorption between the SO42- ions and the polymer. The adsorption was closely related to the pH of the sample solutions and occurred due to the strong interactions between the carboxylic acid groups in the polymer backbones and SO42- ions (rather than Na+ ions). However, there was an extremely weak electrostatic adsorptive interaction between the SO42- ions and the long polyether side-chain.

Abstract: Due to the special chemical and physical properties of the LNG, there are some safety risks in LNG transportation. Maritime transportation is the key link of LNG transportation, the safety of which even more directly has impact on the healthy development of LNG transportation. In accordance with the safety management system of “human – machine – environment - control”, the hidden risks linked to the safety management of LNG ship are analyzed in different aspects such as cargo property, ship factors, environment factors, human factors and management factors respectively; Combined the home and abroad rules about LNG, the impact and requirement to safety management to LNG are discussed, too. Then, polices and methods are given responding to the above noticed factors.

Abstract: In the present work, the Cosserat micro-polar continuum theory is introduced into the FEM numerical model, which is used to simulate the stress concentration problems. The stress concentration phenomena around circular hole, elliptic hole and rhombic hole in plane strain condition, are numerically simulated by two types of Cosserat continuum finite elements of the standard displacement and rotation u4ω4 and u8ω8 based on Dirichlet principle. It is indicated that, compared with the classical continuum finite element, these two Cosserat continuum finite elements can reflect the steep strain gradient and scale effects occurring in the stress concentration problems, and they can weaken the stress concentration and may get consistent solution with actual situation.

Abstract: The condition of preparing α-hemi hydrate gypsum from FGD gypsum at atmospheric pressure is easy to achieve. It acquires atmospheric pressure and low heating temperature. This paper introduces two different methods of preparing α-hemi hydrate gypsum, aqueous salt solution method and dry dehydration. Use the microscopic characterization of α-hemi hydrate gypsum to identify the product. Observe the crystal of product by stereo microscope and characterize the compounds with Fourier transforms infrared spectroscopy. Investigate the factors’ effects between the two methods.

Abstract: One of the important methods to ensure the durability of cement concrete pavement is utilizing excellent waterproof bond layer. Firstly, based on the mechanism of strength of the thermosetting epoxy asphalt waterproof bond material (EAWBM), the construction temperature which is strictly controlled above 130°C, is insured. Then the amount, the curing time and temperature of the thermosetting epoxy asphalt, are studied as the influencing factors of mechanical properties based on the composite structures of the concrete cement pavement. Finally, through the three-point bending fatigue test of composite structures, the fatigue durability of different waterproof bond material is compared. The results show that: the optimal amount of the thermosetting epoxy asphalt is 0.60~0.80L/m²; the asphalt concrete paving must be carried out within 24~32h after the EAWBM is constructed; the mechanical properties of the material decreases as the increasing test temperature; the waterproof bond materials have greater impact on the fatigue durability for the composite structures of the concrete cement pavement compared with the paving material, and the fatigue durability of the EAWBM is the optimal selection for cement concrete pavement.

Abstract: Effects of crumb rubber of different particle sizes (20mesh, 40mesh, 60mesh, 80mesh and120mesh) and contents (10%, 15% and 20% by weight of the total of CRM asphalt) on the properties of CRM asphalt and change rule of performance of CRM asphalt with reaction temperature and time were studied in laboratory. The results indicate that CRM asphalt has the best performance when the particle size of crumb rubber used is 80 mesh and the content is 15%. The performance of CRM asphalt is strongly depended on reaction temperature and time. When reaction temperature is higher than 200°C and time more than 60 minutes, the viscosity of CRM asphalt significantly decline with reaction temperature rising and time delaying. The performance of CRM asphalt starts aging when reaction time more than 4 hours at high temperature. Based on test results, some suggestions for production and application of CRM asphalt are put forward.

Abstract: The compressive strength of geopolymer prepared from a class C fly ash (CFA) at different curing conditions and mass ratio of water to fly ash were investigated. The geopolymer was activated with a mixed solution of sodium hydroxide (NaOH) and sodium silicate. The results revealed that the obtained compressive strength was in the range of 11.7~61.9MPa and the compressive strength decreased with the increment of the mass ratio of water to CFA (W/F). The geopolymer samples with the highest strength were obtained when W/F was 0.30 with proper delay time 1d before being demoulded and then followed by curing at 60°C for 24h. For geopolymer with lower W/F (0.30), its optimum curing temperature was better not higher than 60°C, however, for the higher W/F, the curing temperature was suit to more than 70°C.