Advanced Materials Research Vols. 168-170

Abstract: In order to explore the mechanism and effect of atactic polypropylene (APP) modified asphalt felt preventing crack, which is used as interlayer between old cement concrete pavement and asphalt overlay, by dint of establishing finite element model, considering tensile modulus of the material, the authors calculated and analyzed the load, temperature and coupling stresses on the key dangerous points. Then, laboratory test of direct-shearing and pullout were carried out. It is indicated that the interlayer stress conditions change with tensile modulus of felt, with a perfect synthetically stress-reduced effect when the modulus reaching 1000MPa; the shearing- destruction displacement of core sample with felt interlayer comes to 7.5mm, 3.0mm more than that without the specific interlayer; the pullout-destruction force of core sample with felt interlayer arrives at 10000N, 6000N more than the other. The results show that APP modified asphalt felt is a kind of better preventing-crack materials between old cement concrete pavement and asphalt overlay, which can efficiently cut down the interlayer stresses and improve its working state.

Abstract: Through crushing, screening and grinding, abandoned mortar power can be used as a mineral admixture to replace cement. Physical-activated, alkali-activated and composite-activated have been researched on activity of abandoned mortar power. Mechanical properties and microstructure were tested by compressive strength, flexural strength, XRD, TG-DSC-DTC and SEM. The results show that: Mechanical grinding and activator can significantly improve the activity of mortar power. Stimulating effect of single activator was not obvious. Composite activator has better effect than signal activator and it can promote further hydration of cement. The mortar which is stimulated by composited activator had higher strength than mortar with single activator. It can be seen from micro-test, the mortar with composite activator had more ettringite and other hydration products, having compact structure.

Abstract: This study focuses on the effect of epoxy emulsion, a binder for producing water-borne intumescent fire protective coating for steel structures. The influence of binder on the fire resistive performance, char formation, thermal stability and bonding strength of the coatings were investigated in detail by using Bunsen burner test, thermogravimetry analysis (TGA), field emission scanning electron microscopy (FESEM) and Instron microtester. It was found that the fire protection performance and foam structure of coating sample D2 was significantly improved by adding 10wt% of epoxy resin which produced the greatest thickness of char layer. In addition, TGA results showed that the residue weight of coating D2 was higher than coating sample D3 with 15wt% of epoxy. This indicated that sample D2 has better anti-oxidation and thermal stability. The results of Instron microtester indicated that the bonding strength of the coatings was improved with the increase of epoxy content.

Abstract: The hot-pressing technology of cement bamboo particleboard was studied by changing hot-pressing temperature, adhesive/bamboo ratio, board density and additives amount of NaHCO₃. Then variance analysis and regressive analysis were conducted on technological parameters. The results indicated that the optimizing technology parameters of cement bamboo particleboard are hot-pressing temperature 130 , adhesive/bamboo ratio 2.8, additives amount of NaHCO₃10%, boardl density 1.2g/cm³.

Abstract: Prestressed concrete pipes construction by hammer cause high excess pore water pressure in deep soft soils because Soil disturbance by violent and poor permeability of soft soil. Taking the typical soft ground in passenger special line from Hang Zhou to Ning Bo as the engineering example, the in-situ measuring of the excess pore water pressure in saturated clay ground during the construction of the piles was carried out, and the comparison analysis with the solutions from Vesic theory was also done. The changing rules of excess pore water pressure and its influence range during the sinking of the piles were studied, which would provide an important basis for the design and construction of the similar projects.

Abstract: This paper studied a sort of way on modeling based on GIS raster model, which can complete preprocessor of finite element analysis, and developed an interface program to complete data conversion from GIS to ANSYS, overcoming the weakness that the process that set up slope model by ANSYS was inconvenient.

Abstract: The crack tip stress field of rock is analyzed under blast loading, and the crack arrest criterion, the conditions of rock crack initiation and crack extension are presented in this paper. The study will help the design of maintaining the stability of stope drift active workings.

Abstract: Subgrade connecting has become an important research project in high-speed railway construction engineering. Combining the hub project of Hefei railway, numerical calculation was executed with different subgrade heights to existing line’s safety operation and subgrade stability by FLAC software. It shows that deformations in the vertical direction of the connection between the new subgrade and the old and the old subgrade surface increase following the increment of subgrade height, and the velocity of deformation increment also aggrandize. Reduction of subgrade height is beneficial to trains safety on existing line and subgrade integration property. It will be instructive to control differentia deformation for the connecting subgrade projects in high-speed railway.

Abstract: Three series of polyaluminum chloride with aluminum concentration 2.50 mol/L (A, C, D series)have been prepared under simulated industrial production conditions and a series with Al concentration 0.150~0.336 mol/L has been obtained using a low-speed alkaline titrimetry(B series). The test results of transmission electromicroscope indicate that the particles of A, C and D series specimens are in the dispersing state, there no particles appear in the flocculating mass and branching state, while the particles of B series specimens at middle and lower basicity appear in the flocculating mass and branching state, at hingher basicity they are in the dispersing state.

Abstract: In this paper the relationship of total internal force between complete debonding situation and complete bonding situation, the calculation formulas of moment distribution between steel tube and filled concrete on the complete debonding condition are deduced from the complete debonding calculation model of CFST arch rib and corresponding differential equations of geometry and internal force. Based on principle of virtual work, the relationships of radial displacement between complete debonding situation and complete bonding situation are deduced, and the results were verified by finite element method. The research results for constant section single tube CFST arch rib indicate that the total internal force of any section on the situation of complete debonding is equal to that on the situation of complete bonding if the axial strain is ignored; the moments of steel tube and filled concrete are distributed according to the ratio of their bending stiffness; the stiffness of CFST rib does not decrease with pure debonding.