Applied Mechanics and Materials Vols. 357-360

Abstract: High-temperature foam ceramics were produced from sludge, Zhongxiang porcelain sand, shale and sand, with addition of SiC 0.15%~0.40% as foaming agent, respectively, sintered at 1130°C~1160°C. The phase composition and micro structure of sintered samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and density, compressive strength and thermal conductivity were evaluated. The results showed that the main phase of amorphous phase plagioclase in sintered samples and interior of samples with a large number of uniformly distributed closed pores, rose sintering temperature and increased SiC addition leading to pores size enlarged and density, compressive strength and thermal conductivity diminished.

Abstract: Polycarboxylate superplasticizer (PCE) was synthesized in non-aqueous system to achieve the rapid transportation and convenient preparation. The results showed that, PCE using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as macromonomer exhibited excellent paste fluidities and retaining properties at 80°C and 75°C, respectively. Fourier Transform infrared spectroscopy (FTIR) measurement confirmed the polymerization between monomers. The synthesized PCE as solid state was dissolved into water to prepare the PCE solution, and its cement application performances were studied systematically. The results showed that PCEs with good paste fluidity retentions exhibited the longest final setting time and the shortest setting time interval. The hydration heat results showed that PCEs with good fluidity properties can significantly delay the hydration process and lower the hydration heat.

Abstract: XRD-Rietveld method has been adopted for quantitative analysis of phases in cement powder, phases in mixed samples of cement and pure calcium hydroxide, and sulfate attack products in cement pastes, based on the TOPAS software. The results show that, Rietveld analysis values show good agreement with the actual levels of mixed samples, and the accuracy degree of Rietveld method is at least as well as that of TG/DSC method which is commonly used in quantitative analysis of calcium hydroxide. By adding appropriate internal standard substance, XRD-Rietveld analysis method can be effectively used in quantitative analysis of sulfate attack products in cement-based materials. This work has practical significance on the study of sulfate attack of cement-based material.

Abstract: The mechanically improved foam glass composite toughened by mullite fiber was prepared by sintering technique, using waste sodium-calcium silicon flat glass powder as main raw materials. In this study, the preparation and properties of the samples were characterized by field-emission scanning electron microscopy (FESEM) and mechanical property test. The specific strength of the composite was defined for the first time, and applied into the investigation of mechanical property. The results show that with the increasing of the content of mullite fiber, the pore size of foam glass tends to be uniform and the obturator structure increased. But too much mullite fiber is added can produce a lot of microporous, flexural strength and density increased with the increase of mullite fiber content, when adding 10% (mass fraction) of mullite fiber, the maximum specific strength can reach 0.012m²/s².Good correlations between the microstructure (in particular the fiber distribution), the high specific strength and the high modulus of elasticity of mullite fiber.

Abstract: In order to improve workability of manufactured-sand mortar, limestone manufactured-sand mortar mixed with bentonite, and discussed the role of different dosage of bentonite that had played on mortar fluidity, consistency, layered degree ,mortar compressive and flexural strength. The results show that, mortar water demand increases, fluidity, consistency, stratification decreases with increasing bentonite dosage. Bentonite can be good to improve the water retention properties of the mortar. Doped bentonite mortar strength improved, when doped with 0.9%, mortar has best water retention, flexural, compressive strength also reached maximum.

Abstract: There has been a long history of applying metal to architecture. At the beginning, they just appeared in the structure of bridges, factories and storages, and then gradually turned up as a form of building structural materials in civil architecture such as markets, schools and office buildings. So all the time, metal like steel structure or hardware impresses people as a kind of industrialized building materials. With the development of architectural technology and the researching of characteristics of building materials, metal material has been brought in building skin design with brand-new appearance, and coruscate new vitality in the field of architectural design depending on full of variety of expressions and economic environmental character.

Abstract: In order to study the mechanistic differences between recycled aggregate concrete (RAC)and normal aggregate concrete(NAC), the magnifier and scanning electron microscope were used to observe the meso-interfacial structure and microstructure of interfacial transition zone morphology of the RAC respectively, and analysed differences between RAC and NAC; Secondly, the finite element software ABAQUS was used to simulation the simplified model of RAC. The above analysis results show that, there existe a transition zone in the interface, the aggregate-new mortar interface as well as the new-old mortar interface has been obvious cracks before loading, this part is the weak link of RAC ;After loading, the crack occurs first in the old interface, then appeared at the new interface, and then develop to the old mortar, finally, there formed a through crack.

Abstract: Combined with strain gauge measurement method, the modified split Hopkinson pressure bar was adopted to investigate the behavior of normal concrete and steel fiber reinforcement concrete exposed to 400°C and 800°C under axial impact compressive loading. The experimental results show that compared with normal temperature, the compressive strength and elasticity modulus of normal concrete exposed to 400°C and 800°C decrease obviously. The transformation of concrete exposed to high temperature in microstructure is analyzed by SEM. The influence of high temperature on macro mechanics performance is discussed.

Abstract: Self-compacting concrete(SCC) is the current trend of new concrete.A variety of materials have been added in it on the purpose of changing the properties of SCC[1].In this paper,three viscous materials of limestone powder, silica fume and metakaolin have been added in SCC to change self-compactability and strength.

Abstract: Using MgO type expansive agent is considered as a convenient and effective method to reduce cracks in dam concrete, but the research on autogenous volume deformation of concrete with MgO type expansive agent under the temperature history of real structure is still unclear. In this paper, the temperature history of a diversion tunnel concrete was selected to discuss the autogenous volume deformation of concrete with different activities and dosages of MgO type expansive. The results showed that the autogenous volume expansion of concrete with MgO type expansive agent increased with the content and the activity of MgO type expansive agent. The expansion values of concrete with the content of 4%, 5% and 6% MgO type expansive agent are 51×10^-6, 85×10^-6 and 105×10^-6 in temperature rise stage, and 43×10^-6, 56×10^-6 and 71×10^-6 in temperature decrease stage. The expansion values of concrete with the activity 31s, 138s and 240s MgO type expansive agent are 36×10^-6, 51×10^-6 and 66×10^-6 in temperature rise stage, and 32×10^-6, 43×10^-6 and 62×10^-6 in temperature decrease stage. After 150d the autogenous volume deformation due to MgO type expansive agent did not increase any more.