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Ai T.,Chang'an University | Xiang S.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Wang Z.,Chang'an University
Journal of Materials in Civil Engineering | Year: 2016

As a long-life road surfacing material, epoxy asphalt has many benefits such as high strength, excellent bonding properties, high temperature stability, and high resistance to low temperature cracking. With the increasing use of epoxy asphalt in orthotropic steel bridge deck pavements, there has been an urgent need for a fast, easy, and reliable maintenance method. Microwave heating provides a promising method for epoxy asphalt curing. This study explored the possibility of using microwave heating for epoxy asphalt curing and investigated the effects of microwave heating on chemical and physical properties of epoxy asphalt. An epoxy asphalt suitable for microwave heating was prepared, tested for its tensile properties, and characterized using thermal analysis, infrared analysis, and microscopy tests. The results showed that the epoxy asphalt cured by microwave heating had a better ductility than that cured by conventional heating. The fluorescence and scanning electronic microscopy (SEM) observations showed that microwave curing could reduce the size of asphalt particles dispersed in the continuous phase of epoxy, thus improving the compatibility between epoxy resin and asphalt. © 2016 American Society of Civil Engineers.


Wu H.,Central South University | Huang B.,Tongji University | Huang B.,University of Tennessee at Knoxville | Shu X.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Yin J.,Central South University of forestry and Technology
Construction and Building Materials | Year: 2016

Due to increasing generation of solid wastes from papermaking industry, major concerns arise about the disposal of the solid wastes and their adverse impacts on environments, in which the disposal of paper sludge massively produced from paper mills has become one of the most serious solid waste problems worldwide. In this study, laboratory experiments were conducted to evaluate the feasibility and applicability of incorporating solid wastes from paper mills into controlled low strength material (CLSM), in which fly ash was used as a substitute for cement, bottom ash was added by partially replacing fine aggregate, and paper sludge was treated as a fibrous admixture. Results show that both fly ash and bottom ash could be effectively used in production of CLSM mixtures with desired performances. By limiting the amount of cement used in the mixture, the ultimate strength of CLSM could be controlled for easy excavation. Fly ash could effectively increase flowability of the mixture, thus improving self-compactibility. Both bottom ash and paper sludge had an adverse effect on the flowability. The strength of CLSM was reduced when a higher content of fly ash was incorporated to replace cement, while the strength was increased when more river sand was replaced with bottom ash. Due to a high water absorption and poor dispersibility of paper sludge, the CLSM made with additional paper sludge exhibited a relatively low flowability and a reduction in strength. However, with proper mixture design, paper sludge could still be effectively used in CLSM. © 2016 Elsevier Ltd. All rights reserved.


Meng L.,Shijiazhuang University | Zhang L.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Wang Z.,Shijiazhuang University
International Journal of Earth Sciences and Engineering | Year: 2015

The governing equation of fluid-solid coupling based on Biot’s consolidation theory is deduced. The excavation procedure of the pit is simulated to investigate the effect of different excavate rate on surface settlement, displacement of pile top, basement uplift, effective stress and excess pore-water pressure of the soil behind the pile. Simulation results show that the time effect has obviously influence on the stability of deep pit excavation, such as excavation rate, and excavation steps according to the stress path analysis. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.


Zhang L.-Q.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Chen J.,Hebei East Plan Architecture Design Co. | Qu C.-L.,Hebei Research Institute of Construction and Geotechnical Investigation Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Based on the project cases in Karst region of Tangshan in recent years, some issues occurred in karst treatment and pile foundation construction are analyzed according to the differences with litho logy, karst developing characteristic and karst treatment method. The methods of karst treatment together with the construction technology of pile foundation are sumarized combining with the technical measures and the application of pile foundation adopted in karst treatment. Meanwhile, comprehensive analysis of the measured values of end bearing, skin friction, pile body stress, pile body compression and pile top settlement is conducted according to the core recovery and RQD of the pile tip resistant layer. The results are regarded as the basis of treatment method and design in similar projects. Aiming at karst developing characteristics and common issues in pile construction, effective construction method, technology and measures are proposed, and it may helpful for the pile foundation construction in similar projects.


Zhao Q.,Yanshan University | Yu J.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Geng G.,University of California at Berkeley | Jiang J.,Nanjing Southeast University | Liu X.,Yanshan University
Construction and Building Materials | Year: 2016

In this paper, the effect of fiber types such as steel fiber, polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber and basalt fiber, on the creep of concrete after one-year-loading was studied and the principle of fiber's effect on concrete creep was analyzed. The elastic modulus of fibers is shown to be the most significant factor influencing concrete creep. Fibers with elastic modulus much higher than plain concrete can clearly restrict creep, while fibers with lower elastic modulus have the opposite effect. For example, 2% volumetric blending of steel fiber reduces specific creep by 25.1%, compared with plain concrete, while 0.9 kg/m3 mass blending of PVA fibers increases it by 19.9%. The internal defects introduced by fiber addition, i.e., the fiber-concrete interfacial zone and non-uniform fiber distribution, weakens its creep resistance. There is a clear correlation between the 28 days elastic modulus of fiber reinforced concrete (FRC) and its long-term creep behavior, indicating that they are influenced by similar factors. Larger elastic modulus at 28 days tends to yield less specific creep at 1 year. © 2015 Elsevier Ltd. All rights reserved.


Yang Z.-J.,China University of Mining and Technology | Liang X.-L.,Shijiazhuang University of Economics | Wang H.-M.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Wang D.-L.,Hebei Research Institute of Construction and Geotechnical Investigation Co.
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

The scheme based on the Fiber Bragg Grating(FBG) for measuring the concrete strains of the drilling shaft lining during sinking of Wenjiazhuang Iron Ore Mine auxiliary shaft was introduced, and the variation of the measured strains was discussed.The results show that the concrete bear compressive strain during drilling sinking, the tangent compressive strain is greater than the vertical and the strain variation phases is corresponding to the sinking phases.In the floating and dropping phase the strain curves presented 'bilinear' feature and the measured value is in agreement with the calculated value of the derived formula; in the adding water phase the tangent compressive strains reduce while the vertical increase; in the first grouting phase the compressive strains reduce significantly, and some even become tensile.In the sequent three grouting phases the compressive strains increase first, then partially recover; in the drainage phase the tangent compressive strains increase and the vertical strains change a little; in the additional grouting phase the compressive strains increase first, then partially recover a less part as comparing to the preceding grouting.


Li H.-W.,Beijing Jiaotong University | Nie Q.-K.,Hebei Research Institute of Construction and Geotechnical Investigation Co.
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

Based on a large number of measured data for pile-anchor retaining structures used in deep an excavation in-situ, the evolutions of ground surface settlements, the horizontal displacements, the cap beam horizontal displacements with time were analyzed. Besides, the evolutions of internal stress of retaining piles(i. e. the reinforcement stresses inside cap beam and retuning piles, bending moments of piles) and earth pressure distribution of piles were also discussed. Based on the dynamic evolution concept of deformation and force, the relationship between these physical values(i. e. the deformation and force) of retaining structures in space and with time was studied.


Bai B.,Beijing Jiaotong University | Nie Q.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Wu G.,Beijing Jiaotong University | Su Z.,Beijing Jiaotong University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2010

A model for double-row-pile retaining structures which considers three dimensional effects of deep foundation pit was proposed. This model has the following characteristics: the stiffness coefficient of top beams along the side of a foundation pit can be calculated, and the displacement and bending moment distributions of top beams can also be obtained; the stresses and displacements along the piles can be calculated using finite element method, including any pile distance (zero pile distance is considered as a single row) and different pile length between the two rows. A calculation program is developed based on the above model. The results show that the horizontal displacements of the top beam are bigger in the middle of the pit side than those at other locations, and the horizontal displacement also increases along with the depth of excavation. The displacements at the top of piles are smaller due to the effects of the top beams, but the displacements at the half height of the piles increase along with the excavation depth. Besides, with the increase of the stiffness coefficients of top beams, the displacements of the piles decrease and the bending moments in piles increase. The calculation results are in good agreement with the measured data in-situ.


Nie Q.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Bai B.,Beijing Jiaotong University | Li H.,Research Center for Geotechnical Engineering Technology of Hebei Province | Yu T.,Beijing Jiaotong University
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015

A convection-diffusion transport model of soluble contaminant suitable for one-dimensional homogeneous unsaturated three-layered soils is established. The transport processes of soluble contaminant are analyzed by a semi-analytical method, which takes into account the boundary conditions of pond infiltration. Various combined soil layers and various absorption models (e.g. linear or nonlinear adsorption) are discussed. Studies show that, under pond infiltration, the immigration velocity in coarse grained soil will be greater than that in fine grained soil; furthermore the diffusion ratio of the former will also be higher than the latter. Besides, the influence of initial pressure head on immigration velocity can be neglected; however the concentration peaks of contaminant will increase with the decrease of initial pressure head.


Nie Q.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Bai B.,Beijing Jiaotong University
Geotechnical Special Publication | Year: 2014

This paper investigates the consolidation and shear strength of compacted red clay samples (before and after inundation) in Guangxi, China through laboratory tests. The unconfined shear strength of both undisturbed and remolded specimens in the process of reducing or adding water content was also studied. The studies show that, in moisture-density curves, the maximum dry density of the remolded specimen is greater than that of the undisturbed specimen. However, the optimum water content of the former is smaller than that of the latter. When the compacted specimens are subjected to a vertical load, the vertical deformation reaches steady state in a short time with a small value. After inundation, the increment of the vertical deformation is also very small. However, the unconfined shear strength of the red clay specimens with slightly higher water content is much better than that of those with lower water content. The test results also show that the dehydration or humidity absorption has significant effect on the shear strength of red clay, especially for the remolded specimen. © 2014 American Society of Civil Engineers.

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