Advanced Materials Research Vols. 168-170

Abstract: Waterproofing is one of the key problems of underground structures. Spray-on waterproofing membrane is a new system in tunnels with single shell linings. The conditions of the application of this system are analyzed in terms of the deformation and surface condition of the first layer of the shotcrete shell, water ingress and water pressure behind the waterproofing membrane. The results show that the applications of a spray-on waterproofing membrane in a tunnel is possible if the deformation of the shotcrete and water pressures behind the sprayed membrane is properly controlled, as well as the ingress water is piped or tightened with practical measures. Proposals of measures to meet the conditions are presented for the application of the spray-on waterproofing membrane in tunnels.

Abstract: The macro structures, microstructures, textures and precipitates in non-oriented electrical steels were studied by means of optical microscopy, scanning electron microscopy (SEM), electron back scattering dispersion (EBSD) and transmission electron microscopy (TEM) in the specimens produced by conventional continuous casting process and thin slab continuous casting and direct rolling process. Results showed the macro structures in as-cast slabs and the microstructures in as-rolled strips were more fine-grained and uniform with regard to compact strip production (CSP) process, compared with that in conventional process. No obvious texture was observed in hot rolled strips produced by CSP process.

Abstract: The mechanical properties of the heat treated 65Mn steel that produced by CSP (Compact Strip Production) and conventional continuous casting process were investigated. Measured results showed that 65Mn steel produced by CSP exhibits higher hardness than that produced by conventional continuous casting process. The better mechanical property was attributed to fine-grained microstructures in the as-rolled CSP strips.

Abstract: The nucleation of intragranular acicular ferrite in the welding heat-affected zone of Ti-bearing high strength low alloy steel was investigated by means of electron microscopy. It was found that intragranular acicular ferrite nucleation sites under different welding heat inputs (4.3kJ/mm and 10.0kJ/mm) are titanium complex oxides on which manganese (Mn) sulfides are precipitated. The complex compound is a Si and Mn-enriched oxide. Analysis of the oxide by means of enenrgy dispersive X-ray spectrum indicated that the oxide has higher absorption ability of Si than that of Mn.

Abstract: 12Cr2Mo1R is a high strength pressure vessel steel used in the petrochemical industry. The mechanical and physical properties of the steel 12Cr2Mo1R which was developed in Wuhan Iron and Steel (Group) Company, were investigated in the present work. Test results showed that the steel 12Cr2Mo1R exhibits a high strength at room temperature and high temperature, high strength along Z-direction, and also has very good impact toughness at lower temperatures. The density, linear expansion coefficient and elasticity modulus were also measured. The measured values are all higher than the corresponding specifications of national standards. The uniform mechanical properties and physical properties is attributed to homogeneous microstructure through steel plates.

Abstract: A high strength low alloy wear-resistant steel was quenched at 900°C and tempered at varying temperatures. The microstructures were observed utilizing optical and electron microscope. Results show that microstructures consist of predominantly martensite and lots of bainite in the as-quenched specimens. When the specimen was tempered at 250°C, no obvious change in the microstructure was observed. It has an optimized strength and elongation in this condition of heat treatment. With the increase of tempering temperature, the lath or plate of martensite were coalescenced. The strength of the steel is thus greatly reduced and the elongation was accordingly increased.

Abstract: Organophilic montmorillonite (OMMT)/SBS modified bitumen composites were prepared by melt intercalation. The physical properties and ageing properties of OMMT/SBS modified bitumen were investigated. The results showed that OMMT/SBS modified bitumen exhibited a decreasing penetration, an increasing softening point, and a decreasing ductility. Compared with that of SBS modified bitumen, the OMMT /SBS modified bitumen can enhance the aging resistance of SBS modified bitumen.

Abstract: Permeable concrete pavement is experiencing high solar radiation, air temperature, wind speed, rainfall and other natural factors cyclical influences. These factors and the high permeable concrete pavement surface heat exchange, making permeable pavement temperature inside the high instability of the heat generated. In this paper, convection, radiation, heat conduction transfer of three basic ways to analyze the high-permeable concrete pavement of the heat transfer mechanism in order to determine the boundary conditions and numerical simulation of temperature field basis.

Abstract: The disadvantages of traditional hot asphalt mixture were very obvious in repairing damaged asphalt concrete pavements, which was affected by seasons easily and highly construction condition requirement. Therefore, the study on cold patch material for asphalt concrete pavements became so necessary for curing and repairing in time, and insuring traffic smoothly in winner. The developing history of cold patch material was reviewed, and the characters of typical cold patch material at home and abroad were analyzed also in this paper. The main problem and research direction of cold patch material were put forward based on damaged pavements resulted from icing in plateau and humid region, especially, the snowstorm in southern China early in 2008. References were offered for the future research of cold patch material so that improved serve life of highway.

Abstract: The main problems of repair materials for concrete pavement are big shrinkage and weak bond etc. The rapid repair material discussed in this paper is concrete with compound early-strength admixture. Its compressive strength and flexural strength (1d) is up to 23.1MPa and 3.74MPa respectively, which meets open to traffic demand in one day. Repair materials mixed with alkali-proof glass fiber or polypropylene fiber mesh were studied. Flexural strength and interfacial bond strength increased, shrinkage value reduced when fiber was blended. The results indicate that there is a strong linear correlation between splitting strength of repair material and bond strength.