Advanced Materials Research Vols. 374-377

Abstract: This paper introduced a method of saving materials and energy through making small hollow blocks with the slag admixture in the lightweight aggregate concrete. Through orthogonal design, this paper took slag content, water binder ratio and admixture dosage into consideration and focused on influence of slag content on the physical and mechanical properties of lightweight aggregate concrete small hollow blocks. The results show that: when water binder ratio ，admixture dosage and curing system keep a fixed level, during the range of slag content 30%-40%, with the increase in slag content, the compressive and bending strength of small hollow block increased first and then decreased; water content and absorption and relative water moisture content decreased first and then increased; frost resistance increased then decreased; softening coefficient first increased and then decreased. When the slag content is 35%, the physical and mechanical properties of lightweight aggregate concrete small hollow block are the best, and all the indexes of physical and mechanical properties can meet the standard requirements non-bearing lightweight aggregate concrete hollow block. The curing system significantly affected the strength of the lightweight aggregate concrete small hollow block, and the block strength cured under the standard condition was higher than those under natural condition.

Abstract: The microstructure and hydration mechanism of alkali-activated fly ash-based geopolymer were studied by means of scanning electron microscope (SEM) coupled with energy dispersive X-ray analysis (EDXA) and field emission scanning electron microscope (FESEM). The FESEM photomicrographs indicted that the fly ash-based geopolymer showed three dimensional frameworks with an average particle size of 50 nm. EDXA results demonstrated that the Na-PSS type geopolymer was produced via the disintegration of Si-O-Al and Si-O-Si chemical bonds and the polycondensation reaction between [SiO4]4-and [AlO4]5- tetrahedrons in spherical fly ash particles under alkaline condition.

Abstract: For revealing the behaviors of modified concrete materials against eroding from composite solution, accelerated deterioration tests of Portland concrete, polypropylene fiber concrete, fly ash concrete and concrete mixed with polypropylene fiber and fly ash were made under continuous immersion in two types of composite corrosion solutions, which were sulfate composite solution and magnesium composite solution. The compressive strength, splitting tensile strength and elastic modulus of modified concrete subjected to corrosion were detected. The results show that capacity of corrosion resistance of concrete is enhanced remarkably by modifying approach of mixing fly ash and polypropylene fiber into concrete. The deteriorated splitting tensile strength of modified concrete is able to be increased by 30%-60% compared with ordinary concrete. The research results are benefit to engineering design and application.

Abstract: Uniform design was used to prepare and optimize the cement-based capillary crystalline water- proofing coating. Also the experimental data were analysized by DPS software and the optimization of coating formulations were obtained as follows: content of Ⅰwas 1.06%, content of Ⅱwas 0.57%, content of Ⅲ was 4.7%, content of Ⅳ was 1.36%, content of Ⅴwas 0.24%.

Abstract: The influence of stabilizer on the crystal shape and stability of hemihydrate calcium sulfate whiskers was investigated in detail. Morphology, surface group and phase composition of stabilized hemihydrate calcium sulfate whiskers were characterized by means of SEM, FTIR and XRD, and then effect mechanism was discussed. The results showed that the absorption state of sodium oleate will be different with respectively additive amount which cause whiskers shape and stability to change, and that the stability of hemihydrate calcium sulfate whiskers can be achieved without affecting crystal growth by adding agents in different steps.

Abstract: In this study, the effect of micro-expansion high strength grouting material (EGM) and Modified polypropylene coarse fiber (M-PP fiber) on the mechanical properties of lightweight concrete are investigated. The influence of EGM and M-PP fiber on compressive strength , flexural strength and drying shrinkage of concrete are researched, and flexural fracture toughness are calculated. Test results show that the effect of EGM and M-PP fiber volume fraction (Vf) on flexural strength and fracture toughness is extremely prominent, compressive strength is only slightly enhanced, and the rate of shrinkage is obviously decreased. It is observed that the shape of the descending branch of load-deflection and the ascending branch of shrinkage-age tends towards gently with the increase of Vf. And M-PP fiber reinforced lightweight aggregate concrete is more economical.

Abstract: In this paper, basing on Hu haichang’s theory and using Fourier transformation, the problem is changed into solving fourth-order and second-order linear ordinary differential equations. The eigenvalue method is used for solving these equations, and then both displacement and stress with undetermined coefficients can be received. Considering the boundary conditions, the exact displacement and stress of the transversely isotropic foundation can also be gotten. Especially on the transversely isotropic elastic half space, with the aid of computer software, a more simple vertical displacement is presented. When the foundation is degenerated into isotropic elastic half space, the displacement is also degenerated into elastic half space displacement in a rectangular coordinate system which is given in the reference. And this exactly proves the result which is received from this paper is right. On this basis, we can analyze a settlement of transversely isotropic foundation and the static characteristics of rectangular plate on the transversely isotropic foundation.

Abstract: Fiber reinforcement as an available attempt has been proved to be effective in improving the toughness of asphalt concrete and is becoming a new method for highway maintenance. When fiber modified asphalt mixture is used as the surface course of a reconstructive pavement, the interface bonding property between top and lower layers seems to become a crucial factor in the road performance of the long lasting pavement. The primary objective of the research is to study the influence of fiber inclusions on the interfacial shear property of the pavement. With the purpose of discussing the shear strength of the interface between Bonifiber modified asphalt mixture top layer and the normal asphalt mixture layer，the laboratory shear test was developed on MTS-810. Four kinds of double-layered cylindrical specimens were made to simulate the different pavement structures. Test results show that the overlaying with Bonifiber modified asphalt mixture improves not only the general road performance but also the interface property. It is concluded that, the interface property of pavement with fiber reinforced top layer behaves much better than that with normal asphalt concrete one.

Abstract: The semiconducting Cu3N films were successfully deposited on glass substrates by reactive radio-frequency magnetron sputtering in a mixture gas of nitrogen and argon. The influence of nitrogen content in a fixed total sputtering gas flow on the preferential crystalline orientation, the mean crystalline grains size, the electrical resistivity, the microhardness, and the reduced modulus were investigated. X-ray diffraction analysis shows that the films were polycrystalline Cu3N and the preferential orientation is greatly affected by the N2 content. The mean crystalline grain size of these as-deposited Cu3N films decrease and the electrical resistivity increase from 1.51×102Ω•cm to 1.129×103Ω•cm with increasing N2 content. And the microhardness and reduced modulus are 6.0GPa and 108.3GPa, respectively. The sectional SEM and planform AFM observations reveal that the films have smooth surfaces with columnar grains.

Abstract: In this paper, the thermophysical properties, such as thermal conductivity, thermal diffusivity, specific heat capacity and linear thermal expansion of reactive powder concrete (RPC) with different steel fiber volumetric fractions are investigated by means of thermophysical experiments. The empirical relationships of thermophysical properties with temperature and fiber volume are established. The results indicate the temperature and fiber volumetric fractions have different effects on the thermal properties of RPC.