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  • Improving the Dispersibility of Poly(urea-formaldehyde) Microcapsules for Self-Healing Coatings Using Preparation Process
  • Abstract Poly(urea-formaldehyde) (PUF) microcapsules were prepared by in-situ polymerization with four different processes in this paper. The chemical composition, surface morphology, particle size distribution, and thermal stability were characterized by FTIR, SEM, particle size analyzer, and TGA, respectively. The results demonstrated that the agglomeration of the PUF microcapsules was related to the agglomeration of the emulsion particles caused by the changes of emulsion interface during the shell polymerization. Due to the slow deposition of the shell material, the PUF microcapsules with the core-shell structure prepared by the process with ammonium chloride as the last additive showed good dispersibility with an average…
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  • Mechanical Properties and Constitutive Relationship of the High-Durable Parallel Strand Bamboo
  • Abstract Engineered bamboo has recently received lots of attention of civil engineers and professional researchers due to its better mechanical performance than that of softwood timber. Parallel strand bamboo is one important part of engineered bamboo for its excellent durable performance compared to the laminated veneer bamboo. The required curing temperature in hot-pressing process is usually higher than 120°C to reduce the content of nutritional ingredients and hemy cellulose, and to avoid the decay from the environment and insects. Nonetheless, the appearance of engineered bamboo gets darker with the increase of temperature during the hot-pressing process. In order to minimize the…
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  • Numerical Investigation of Connection Performance of Timber-Concrete Composite Slabs with Inclined Self-Tapping Screws under High Temperature
  • Abstract The timber-concrete composite (TCC) slabs have become a preferred choice of floor systems in modern multi story timber buildings. This TCC slab consisted of timber and a concrete slab which were commonly connected together with inclined self-tapping screws (STSs). To more accurately predict the fire performance of TCC slabs, the mechanical behavior of TCC connections under high temperature was investigated by numerical simulation in this study. The interface slip of TCC connections was simulated by a proposed Finite Element (FE) model at room temperature, and different diameter and penetration length screws were considered. The effectiveness of this FE model was…
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  • Preparation and Performance of a Fluorine-Free and Alkali-Free Liquid Accelerator for Shotcrete
  • Abstract Based on aluminum sulfate, a fluorine-free and alkali-free liquid accelerator (FF-AF-A) was prepared in this study. The setting time and compressive strength of three cement types with different FF-AF-A dosages were fully investigated. The compatibility of the FF-AF-A with the superplasticizers were also investigated, and the early hydration behavior and morphology of the hydration products of reference cement paste with the FF-AF-A were explored by hydration heat, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Test results indicated that adding the FF-AF-A at 8 wt% of the cement weight resulted in 2 min 35 s initial setting time and 6…
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  • Different Effects of Wet and Dry Grinding on the Activation of Iron Ore Tailings
  • Abstract Improving the activity of Iron Ore Tailings (IOTs) to utilize them as a mineral admixture in cement-based minerals is still challenging. In this paper, the wet grinding technology was employed to stimulate the activity of IOTs, and the traditional dry grinding method was used as a reference. The effect of wet grinding on the activation of IOTs was evaluated through ion leaching from an alkaline solution and the reactivity index. Additionally, a detailed comparison between Dry-grinding Iron Ore Tailings (DIOTs) and Wet-grinding Iron Ore Tailings (WIOTs) was made. This comparison was based on particle characteristics, crystal structures, chemical structure, and…
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  • Long-Term Loading Test of Reinforced Glulam Beam
  • Abstract Due to creep characteristics of wood, long-term loading can cause a significant stress loss of steel bars in reinforced glulam beams and high long-term deflection of the beam midspan. In this study, 15 glulam beams were subjected to a 90-day long-term loading test, and the effects of long-term loading value, reinforcement ratio and prestress level on the stress of steel bars, midspan long-term deflection, and other parameters were compared and analyzed. The main conclusions drawn from this study were that the long-term deflection of the reinforced glulam beams accounted for 22.5%, 20.6%, and 18.2% of the total deflection respectively when…
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  • A Study of the Structural Evolution and Strength Damage Mechanisms of PishaSandstone Cement Soil Modified with Fly Ash
  • Abstract In the present study, in order to investigate the effects of fly ash on the structural evolution and strength damage mechanism of Pisha-sandstone cement soil, unconfined compressive strength tests of Pisha-sandstone cement soil with different fly ash content levels and various ages were carried out. The apparent morphology, microstructures, and chemical compositions of the samples were observed and analyzed using ultra-depth three-dimensional microscopy, scanning electron microscopy, and XRD methods. The results revealed that the unconfined compressive strength levels of Pisha-sandstone cement soil samples displayed increasing trends with the increases in fly ash content and age. For example, when the fly…
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  •   Views:967       Downloads:235        Download PDF
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