Advanced Materials Research Vols. 261-263

Abstract: The application of Aluminum alloy T-stub joints has been found widely in China recently, while the research achievements of the joint are far from adequate for design. This paper is focused on the ultimate load-bearing capacity of aluminum alloy T-stub joints. On the basis of Kulak prying model, formulas for calculating ultimate load-bearing capacity, considering four types of failure modes, are derived. The numerical simulation is carried out by means of ABAQUS FEA. Numerical results are verified by comparing with previous results obtained from experimental analysis. A parametric analysis is performed to investigate the influence of several geometrical parameters on the behavior of aluminum alloy T-stub joints including failure modes, ultimate load-bearing capacity and effective length of flanges. These numerical results are also compared with those calculated by relevant formulas in EC9.

Abstract: Sandwich panels consisting of two aluminium two face-sheets and a core made of aluminium honeycomb were studied in this paper. These sandwich panels are good candidates for cladding systems employed to protect other structures again blast loadings. In this paper, the mechanical response and deformation of these sandwich panels subjected to simulated blast loadings are investigated experimentally. The effects of impact pulse, foil thickness and cell size of aluminium honeycombs have been discussed.

Abstract: Using a Gleeble 1500 thermo-mechanical simulator, the behavior of the dynamic recrystallization (DRX) of a low-silicon TRIP steel containing phosphorus and vanadium for automobiles is studied systematically. By the analysis of ture stress-strain curves, critical stress(σ_c) and strain(ε_c) are determined at different deformation conditions. The deformation activation energy Q_def is 323 kJ/mol. The ratios of ε_c/ε_p and σ_c/σ_p of the tested TRIP steel are 0.553 and 0.89, respectively. The equation for describing the Zener–Hollomn formula for tested steel is derived. A linear equation between σc, σp, εc, εp and lnZ have been established through regression analysis, respectively.

Abstract: Roof and wall are known to be responsible for heat entering into a building and should therefore be thermally insulated in order to lessen energy consumption required for air-conditioning. In this study, four soil-based aerated lightweight concrete (ALC) panels each measures 750 mm (length) x 750 mm (breadth) x 70 mm (thick) with different aerial intensity of newspaper membrane encased were produced and tested on their thermal insulation property. For environmental friendly and economy reasons, clayey soil was used in place of sand to produce the ALC panels and they were tested in the Thermal Laboratory for twenty hours. Temperature gradient was computed based on the surface temperature measured during the test. The results obtained indicated that newspaper membrane encased soil-based ALC panels have superior heat insulation performance compared to control panel in terms of temperature gradient. It is found that the temperature gradient increased from 1.92 °C/cm to 2.08 °C/cm or 8.3% higher than control panel with just merely 0.05 g/cm² of newspaper membrane encased.

Abstract: Condensed silica fume (CSF) is often added into concrete mixes to enhance the properties of concrete. However, the effect of CSF on the heat evolution and temperature rise of concrete is not clearly known. Test results in the literature are insufficient and sometimes contradictory to enable any conclusion to be drawn regarding the role of CSF in heat generation behaviour of concrete. Moreover, since the chemical reactions of cement and CSF both involve water and hence cement and CSF are competing with each other in reacting with water, the water to binder (W/B) ratio may affect the temperature rise characteristics of concrete. This paper reports an experimental study of adiabatic temperature rise of CSF concrete conducted at The University of Hong Kong. Five concrete mixes without CSF and 10 concrete mixes with CSF dosages at 5% and 10% were tested with the recently developed semi-adiabatic curing test method. The adiabatic temperature rise was obtained by applying heat loss compensation to the test results. It was found that the addition of CSF could suppress the adiabatic temperature rise of concrete. At the same time, the strength of concrete could be enhanced. Based on the experimental results, prediction formula and design chart of adiabatic temperature rise of CSF concrete were developed.

Abstract: Aiming at the characteristics of phosphate repair material, by mixing fly ash in it, its properties can be improved effectively. The experiment has studied the effects of fly ash on the setting time, strength and air shrinkage property of phosphate repair material.the result shows that mixing appropriate fly ash can prolong the setting time, and on the condition of maintain constant fluidity, the strength of phosphate repair material can be enhanced, but with the increase of fly ash admixture, its strength will be reduced, the fly ash admixture within 10% can reduce the air shrinkage of repair material.

Abstract: Recycled fine concrete aggregate can not be directly used for concrete for its large water absorption, so we get recycled concrete powder through grinding process, and carried out series experimental studies on the recycled concrete powder. The results show that the technical parameters of recycled concrete powder can achieve the requirements of S95 grade slag powder. The slump constant of recycled concrete mixed with recycled concrete powder is slightly less than slag concrete, while cohesiveness and water retention is better than slag concrete. Replace slag powder with recycled concrete powder, the recycled concrete has high early strength but post-intensity does not change significantly. The conclusion shows that recycled concrete powder can completely replace slag powder in concrete to realize full efficiency reuse of waste concrete.

Abstract: In this research, the physical and chemical influence of polyacrylate (PA) latex on cement-based materials were studied using polymer modified mortars with polymer/cement (P/C) ratios of 0%, 5% and 10%. Physically, the mechanical performance of PA latex modified mortars was investigated with compression toughness energy and bending strength. Further more, a comparison of the pore structure and porosity between PA latex modified and unmodified mortars was conducted. The chemical reactions between PA polymer and cement hydrates were clarified with thermogravimetric (TG) analysis. It can be concluded from this research that PA polymer can refine the pore structure of cement mortars and link the cement hydration products together chemically. While, at the same time, PA latex addition can cause air entrainment which will weaken the physical behavior of cement mortars. So there is an optimum P/C ratio to achieve the best mechanical properties. And in this research, the optimum P/C ratio is 5%.

Abstract: In the context of sustainable development, traditional approaches such as ocean dumping and inland deposit are unsatisfactory for managing such large quantity of dredged marine sediments. The solidified sediments with cement as a new material for road construction are preferred to resolve the present issue for minimizing the impact to environment. Based on the basal characterization of dredged sediments, a series of tests, such as compaction tests, compressive strength and tensile strength tests and swell tests, are performed to explore the engineering properties of treated materials. The compressive and tensile strengths increase with cement content and curing time, while the swell percents of sediments decrease after immersion in water for 4 days. And this treatment method could be considered adaptive and acceptable for the road construction from the point of view of swelling property. Finally, the I-CBR index of cement-treated sediments increases due to the flocculation and cementation compared to the I-CBR index before immersion.

Abstract: Experiments were performed to investigate the properties of fly ash-calcined phosphogypsum (PG) cementitous materials with PG different thermally treated, including being calcined at 135°C, 430°C and 800°C separately. Durability of the cementitous materials was investigated by determination of mass loss of binders immersed in water for different durations and strength development subjected to various curing conditions. X-ray diffraction analysis was used to study the differences in hydration products among binders with different thermally treated PG. Morphology and microstructure of the hardened binders were investigated by scanning electron microscopy. Results suggest that the binder with PG sintered at 430°C obtains the best performance, indicating both impurities in PG and the form of gypsum influence its utilization greatly. Considering this, it can be concluded that choice of a proper thermal treatment is important.