Advanced Materials Research Vol. 648

Abstract: Ordinary Portland cement is gelling agent. Fly ash was used to replace part of the cement. Light foamed concrete joining physical foaming was produce. The effects of foam dosage on bending strength, compressive strength and coefficient of thermal conductivity of foam concrete were investigated. The results indicate that the increase of the amount of foam can greatly reduce the dry density of foam concrete. When foam dosage is 1.5 L/kg, we can produce light foamed concrete having certain intensity. Its dry density is 424 kg/m3, and heat conduction coefficient is 0.095 W/mk.

Abstract: The red mud lightweight ceramsite was made by using red mud, fly ash and bentonite, mixed with a certain amount of pore-forming agent and foam stabilizer, through the roasting process. Influence of pore-forming agent on red mud ceramsite was studied. The microscopic morphology of red mud lightweight ceramsite damage fracture was analyzed by using scanning electron microscope. The results show that with 6% pore-forming agent, the apparent density is 731kg/m3, the bulk density is 547kg/m3; the cylinder compressive strength is 3.3Mpa, the water absorption is 9.7%.

Abstract: Low-alkalinity steel slag was mixed with FGD gypsum to make the gypsum based cementing material of low-alkalinity steel slag, by adding some appropriate activators. Mechanism of each component was discussed. Results show that, when steel slag-to-FGD gypsum is 1, the initial setting time is greatly shortened to 6min and the final to 9min. Flexural strengths of 2h, 1d and 7d are followed with 2.21MPa, 2.03MPa and 3.59MPa, while the compressive of 2h, 1d and 7d are 5.06MPa, 4.70MPa and 12.55MPa.

Abstract: The ordinary Portland cement as matrix materials and fly ash as a lightweight aggregate were used to prepare a new foamed cement material by chemical foaming method though adding a proper level of foaming agent, foam stabilizer, and glass fiber. The raw materials’ ratio of new foamed cement was determined through the experiment. The microstructure of bubble was analysed by electronic scanning electron microscopy. The mechanism of foam stabilizer and fiber reinforced mechanisms were explored.

Abstract: The construction waste was processed into recycled aggregate to produce solid construction waste brick with grade of MU20. The preparation process of recycled aggregate and the optimal value of mass ratio of water to cement (water cement ratio) and mass ratio of recycled aggregate to cement was studied. The results shows that when the water cement ratio is 0.86 and the mass ratio of recycled aggregate to cement is 5.5 and the dosage of activator is 0.25% (mass fraction with recycled aggregate), the compressive strength of sample is 22.5MPa and can be satisfied with the requirement of MU20 solid concrete brick.

Abstract: In this experiment, cement, fly ash, quicklime, foaming agent and foam stabilizer were used as raw materials to prepare the new foamed cement insulation material. Single-factor tests were designed to study the influence of different dosages of foaming agent, foam stabilizer and quicklime on the material properties. The optimum ratio was determined: content of fly ash was 25%, water-cement ratio was 0.37, content of foaming agent was 4.5%, content of foam stabilizer was 1.2% and content of quicklime was 1.5%. The material is tested: 3d compressive strength of the material is 1.049MPa, 3d flexural strength of the material is 0.608MPa.

Abstract: In order to improve the cellulase-producing ability, the culture medium components and condition were optimized. The results showed that the cellulase activity in the fermentation broth remarkably increased by using 1% corncob residue combined with 1% wheat bran and 1% corncob as carbon source, taking 0.75% soybean meal and 0.3% KON3 as nitrogen source, and adding 0.3% CaCO3 to stabilize the pH to 5.0. The FPase activity in supernatant of A. niger FC-1 fermented with 50mL of the optimal medium in 250mL shake flasks at 30°C reached 101.6U/mL, which was 4.7 times of that before optimization.

Abstract: Based on the cross-section bending of 5 carbon fiber concrete beams, the mechanism of deflection and strain of carbon fiber concrete beam were studied considering the variation of the length of carbon fiber and stirrup ratio. The experimental results show that the deflection of destruction increased with the increase of the length of the carbon fiber, and the effect of stirrup ratio on deflection and strain of beams is not obvious. The carbon fiber can effectively improve the brittle failure of concrete beam, and the stain of concrete accorded with that steel bar at the same height. According to the existing test model, the theoretical calculating formula of CFRC was proposed and applied for the cracking load calculation expression of CRFC beams, and theoretical calculated results agree well with experimental results.

Abstract: In this paper, calcium–alginate beads have been manufactured by physically cross-linked technology, by dripping an aqueous alginate solution into a solution of calcium salt as a crosslinker. The effect of various elements controlling beads shape such as solution concentration, flow rate and the distance between the orifice tip and surface of the cross-linking solution were studied. The various elements affected the gelling rate and diameter and weight were studied. The findings indicated that shape of alginate beads in the hydrated state was strongly dependent on the flow rate and concentration of sodium alginate solutions.

Abstract: The ultra-light calcium silicate material was reinforced with the method of xonotlite whisker in-situ growth via hydrothermal synthesis. Effects of different ratios of silica sources on microstructure and mechanical properties of the reinforcement were studied in this paper. The results indicated that the ratios of silica sources posed great impacts on microstructure and mechanical properties of the reinforcement. The reinforcement with density of 118 Kg•m-3, flexural strength of 0.42 MPa and compressive strength of 0.66 MPa was successfully prepared under the condition of K2SiO3:H2SiO3 (mol) =2:1.