Foam concrete with different dry densities (400, 500, 600, 700, and 800 kg/m3) was prepared from ordinary Portland cement (P.O.42.5R) and vegetable protein foaming agent by adjusting the water-cement ratio through the physical foaming method. The performance of the cement paste adopted, as well as the structure and distribution of air pores, was characterized by a rheometer, scanning electron microscope, vacuum water saturation instrument, and image analysis software. Effects of the water-cement ratio on the relative viscosity of the cement paste, as well as pore structure and strength of the hardened foam concrete, were discussed. Results showed that water-cement ratio can influence the size, distribution, and connectivity of pores in foam concrete. The compressive strength of the foam concrete showed an inverted V-shaped variation law with the increase in water-cement ratio.
Foamed concrete (400 kg/m3) was prepared through a physical foaming method using ordinary Portland cement (42.5R), vegetable protein foaming agent, fly ash, and glazed hollow beads (GHB, K46) as raw materials. The performance of cement paste as well as the structure and distribution of air voids was characterized by rheometry, SEM, and XRD analyses with imaging software. The effects of GHBs on the compressive strength and thermal conductivity of the foamed concrete sample were also explored. Results show that the proportion of 50–400 μm air voids, average air-void diameter, 28 d compressive strength, and thermal conductivity of the test sample mixed with 2.4 wt% GHBs are 94.44%, 182.10 μm, 2.39 MPa, and 0.0936 w/(m·k), respectively. Excessive amount of GHBs (>2.4 wt%) increases the amount of air voids with diameter smaller than 50 μm in the hardened foamed concrete as well as the degree of open porosity. Moreover, the proportion of 50–400 μm air voids, average air-void diameter, 28 d compressive strength, and thermal conductivity of the sample mixed with 4.0 wt% GHBs are 88.54%, 140.50 μm, 2.05 MPa, and 0.0907 w/(m·k), respectively.
The objective of this study was to investigate the feasibility of TiO2 waterborne epoxy resin as fog seal and exhaust degradation material in asphalt pavement. To achieve this objective, a commercial anatase/rutile mixed-phase nano-TiO2 was added to waterborne epoxy resin at various percentages. Prepared TiO2 coating was characterized with the use of adhesive shear strength test and laboratory photocatalytic performance test, which was performed with a newly developed apparatus for the study of vehicle exhaust decomposition. In addition, the impact of TiO2 coating on skid resistance and permeability of asphalt pavement was analyzed, with the British Pendulum, sand patch method, and pavement permeability test. The results of the experiments indicated that TiO2 waterborne epoxy resin coating was very effective in decomposing NO, HC, and CO pollutants from automobile exhaust. Moreover, application of waterborne epoxy resin as fog seal could maintain the skid resistance and improve the impermeability of the pavement.
Ti3SiC2 is a bioinert material. The combination of high fracture toughness, excellent corrosion resistance and easy machinability make it a new class of potential biomaterials for orthopedic applications, dental implants, and fixation devices for the bone. In this paper, effect of Si concentration on the sintering of Ti3SiC2 bulk material was reported. Ti3SiC2 bulks were fabricated by pressureless reactive sintering of powder compacts made of Ti, Si and graphite powders. Nearly pure Ti3SiC2 bulk was obtained by reactive sintering of the powder compact, with a nominal composition of 3:1.1:2 in molar ratio of Ti:Si:C, at 1500 °C for 120 minutes. TiC, a non-preferable impurity was avoided by the appropriate addition of excess Si (relative to stoichiometric composition of 3:1:2 in Ti3SiC2). However, too much Si will result in the formation of significant amount of TiSi2 and SiC in the sintered Ti3SiC2. Microstructure of the prepared Ti3SiC2 bulks was analyzed by scanning electron microscope. Phase constituent analysis was carried out by x-ray diffraction. Effect of Si content on the density of sintered samples was also studied.
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