Applied Mechanics and Materials Vols. 204-208

Abstract: Impregnated paper for plywood formwork is an important material for the production of plywood formwork. It was developing with plywood formwork and the market had been expanding. Absorption and wet strength are main factors which can effects on the property of impregnated paper. In this paper, mechanical chemical pulp and waste paper were used to make special impregnated paper for formwork. The ratio of EMP, dosage of aid, and operation conditions were discussed. The result showed that the absorption was improved by increasing ratio of EMP, adding agent, drying quickly, and lighter pressure. A certain ratio of AOCC is necessary to ensure strength. The paper also discussed the difference of white spot between bamboo plywood formwork and plywood formwork which indicated that white spot caused by waste paper .However, it wasn’t damage the quality of structures.

Abstract: The mixture of isocyanate and urea-formaldehyde adhesive resin was used to manufacture low-cost straw particle board by hot-pressing process. Influence of the hot-pressing temperature, hot-pressing time, board density and the amount of isocyanate adhesive on straw particle board mechanical properties were studied. The resulted showed that, within a certain range, the straw particle board physics performance was improved with the increase of hot-pressing temperature, hot-pressing time, board density and the amount of isocyanate adhesive. The proper hot-pressing process of cost-straw particleboard is hot-pressing time for 40s/mm, MDI applied amount of 3%,a density of 0.7 g/cm3, hot-pressing temperature of 180 °C

Abstract: In order to better master the production process and the road performance of rubber asphalt, the paper studied the influence law of mixing method, mixing temperature, mixing time and rubber powder content on the performance of rubber asphalt. The results show that all the indexes except the viscosity of rubber asphalt has little change with different mixing methods, and the rubber asphalt has the best performance under the high-speed stirring molding method but the worst performance under the high-speed shearing molding method. Meanwhile, the performance of rubber asphalt change visibly with different mixing temperatures, on which the excessively high or low production temperature has negative significance, so the optimal production temperature would be recommended as 180~200°C. Furthermore, the mixing time and the rubber powder content are the two critical factors which may greatly affect the performance of rubber asphalt, followed by the mixing temperature and the mixing method.

Abstract: Abstract: Based on the center-particles hydration dynamic model proposed by Park, a micro-structural hydration model of Portland cement that was built considering the decrease of the hydration rate due to the reduction of free water and the reduction of the interfacial area of contact between the free water and the hydration products. It can be used to predict the variation relationship of the hydration rate increases with the change of hydration degree. The results showed that: the revised model can simulate the variation curve of the cement hydration speed with hydration degree in this paper and the model results agree well with the experimental results.

Abstract: Abstract: Based on the cement hydration kinetics model proposed by R.Berliner, taking into account the factors such as each chemical phase of minerals, curing temperature, water-cement ratio, the final hydration degree and fineness of cement, a theoretical hydration kinetics equations was established in this paper. It can be used to predict the hydration rate and the change of hydration degree.

Abstract: the relationship between hydration products transformation and the compressive strength was studied with X-ray diffraction, infrared spectroscopy analysis. The results showed, 0.505nm hydrogarnets diffraction peaks weakened and 0.183nm CSH diffraction peak enhanced with different autoclaved time under 1.2MPa saturated steam pressure. 0.505nm hydrogarnets diffraction peak enhanced under lower saturated steam pressure for autoclaving 6h, then weaken under higher saturated steam pressure. And 0.183nm CSH diffraction peaks enhanced with different saturated steam pressure for autoclaving 6h. During autoclaving, hydrogarnet translate into Al-substituted calcium silicate hydrate (C-S-H). Transformation of hydration products is favorable for compressive strength of autoclaved sample.

Abstract: The results of the experimental investigation of the developing expansion and contraction strains of both plastering mortar and Expanded Polystyrene Foam (EPS) coatings, during thermal and drying cyclic loading are presented. The mortar used, is cement based with hydrated lime and fine marble aggregates. The EPS specimens were cut from boards of various qualities, appropriate for the external insulation of buildings. Mortar and EPS specimens were subjected to temperature cyclic changes, during which the occurring expansion and contraction strains were recorded. Based on these data, assumptions were made for the nature and the mechanism of the growing strains, in order to collect the necessary information to develop solutions for the critical problem of mortar cracking when applied over EPS insulating boards.

Abstract: This research tried to analyze the effects of ecological materials on indoor environments. For this purpose, two full scale mock-ups were constructed: one with silk wall paper, which is generally used for indoor finishing and the other with hwang-toh (yellow soil), which is the preferred material for wall finishing. Comparison and performance evaluations were conducted, and the effects of hwang-toh finishing on a humid indoor environment were verified. Through this research, it was verified that a hwang-toh plaster finish is effective in maintaining the comfort of an indoor environment

Abstract: This paper investigates the interaction of structural deformed bar reinforcement and strain hardening cement composite (SHCC). The SHCC shows excellent mechanical properties such as multiple cracks and strain-hardening. Generally, SHCC material consists of cement, silica sand and fibers and is rich mixture without aggregate. Rich mixture leads to much shrinkage strain of SHCC material. In this research, the replacement of a part of cement by expansive admixture (EXA) is considered as an alternative to compensate the shrinkage strain of SHCC material. This paper presents the experimental results of tests on tension stiffening and cracking behavior of reinforced conventional and shrinkage-compensating SHCC ties in monotonic and cyclic tension. Each tie specimen had a square cross-section dimension of 100 x 100mm and length of 1,500mm. A 16mm diameter deformed bar was embedded centrally and mixed with 1.5% hybrid fibers composed of Polyethylene(PE) and Steel core(SC). The test results indicated that the shrinkage compensation of cement matrix in SHCC improve the tension stiffening and cracking behavior of reinforced SHCC ties in monotonic and cyclic tension loading.

Abstract: The concrete would crack when the temperature stress caused by hardening concrete hydration heat and shrinkage action were over the concrete’ tensile strength. The concrete were added with different amount of fly ash in order to increase concrete’ tensile strength and ultimate tensile strain capacity or consider economic perspective. The mechanics performance tests were carried on mass concrete with different fly ash bulk volume. The test results showed that the fresh fly ash concrete’ workability, hydration heat, compressive strength and durability were obvious superior compared with ordinary concrete.