Kong X.,Tsinghua University |
Lu Z.,Beijing Building Construction Research Institute Co. |
Yan J.,China University of Mining and Technology |
Liu H.,China University of Mining and Technology |
Wang D.,China University of Mining and Technology
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2013
The influence of triethanolamine (TEA) on the elemental concentrations in the aqueous phase of hydrating cement pastes was investigated via inductively coupled plasma atomic emission spectroscopy (ICP-OES). The results show that the TEA increases the concentrations of Fe, Ca, and Al, as well as those of S, Si, and OH- in the aqueous phase of the fresh pastes. The isothermal calorimetry experiment indicates that the TEA addition of 0.1% increases the first peak of cement hydration and extends the induction period. The total organic carbon (TOC) results show that the TEA in the aqueous phase of the hydrating cement pastes is rapidly consumed in the acceleration period of cement hydration, suggesting that TEA could be incorporated into the hydration products via either chemical reaction or physical adsorption. The measurement of conductivity of saturated Ca(OH)2 solution confirms the formation of the complex between the TEA and calcium ions.
Kong X.-M.,Tsinghua University |
Lu Z.-B.,Beijing Building Construction Research Institute Co. |
Liu H.,China University of Mining and Technology |
Wang D.-M.,China University of Mining and Technology
Magazine of Concrete Research | Year: 2013
The influence of triethanolamine (TEA) at varying dosages on the strength development of pure cement (PC) and fly ash cement (FAC) pastes was systematically investigated. Techniques including mercury intrusion porosimetry, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy were employed to characterise the microstructure of hardened cement pastes and to monitor the cement hydration process with the aim of correlating strength variations with microstructural changes caused by TEA addition. The results showed that 0.03-0.10% addition of TEA visibly enhances the early strength but decreases the compressive strength after 3 d for PC pastes. A high dosage of TEA (1%) leads to a sharp decrease in 28-d strength for both PC and FAC pastes. Mechanistic explanations regarding why TEA affects the strength development differently at different dosages and ages are discussed by considering the impacts of TEA on the hydration degree, pore structure, composition and morphology of hydration products.
Song J.,Beijing Construction Group Co. |
Song J.,Tsinghua University |
Li Z.,Beijing University of Technology |
Wang Y.,Tsinghua University |
Zuo Y.,Beijing Building Construction Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2015
A monotonic axial compression test was performed on two series of short column specimens in order to investigate the size effect of axial compressive mechanical properties of confined concrete. The main test variables were volumetric ratio of stirrup and specimen size. The diameter of largest specimen was 576 mm. The test result shows that as the specimen size increases, the peak stress and the peak strain of confined concrete decreases. The relationship between ductility and specimen size is indistinct. When factorial analysis method is used to analyze the test results, it can be found that the volumetric ratio of stirrup has significant influence on peak stress, peak strain and ductility of confined concrete. The specimen geometric size affects peak stress and peak strain significantly, but no great influence on ductility. The interaction of volumetric ratio and geometric size does not affect peak stress, peak strain and ductility too much. Based on the test and the analysis results, a stress-strain constitutive model in terms of column confined by hoops is established. Its prediction value fits well with the test result of this thesis. ©, 2015, Science Press. All right reserved.
Wang Z.,Beijing Building Construction Research Institute Co. |
Cheng S.,Jinggong Steel Building Group |
You D.,Beijing Building Construction Research Institute Co. |
Yang G.,Government Investment Basic Construction Office of Ordos Ejin Horo Banner |
And 3 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2012
This paper focuses on the solution to the technical problems confronted during the construction process of the cable dome with a diameter of 71.2 m, i.e. the controlling of structural construction error, component size error, installation and shaping methods of structures, the order and method of pretensioning and the construction simulation and monitoring. The internal and middle ridge cables, internal and middle slope cables are fixed length cables. The outer ridge cable and the outer slope cable are variable length cables to adjust the construction error. On the basis of a brief summary of the construction experience abroad, it proposes the method of integral assembling on the ground and synchronous hoisting of outer ridge and slope cable, shaped by stretch the outer slope cable, which has reduced aerial work and guaranteed constriction security. Secondly, based on the theory that the cable dome is a flexible construction with several symmetry axis, the construction method of verified batches and levels was finally proposed, based on which, tension construction of the project was completed. From the monitoring data, the configuration of the actual structure was generally identical with the configuration designed.
Yan X.,Tianjin University |
Wang L.,Beijing Building Construction Research Institute Co. |
Du X.,Beijing University of Technology
Applied Mechanics and Materials | Year: 2013
In order to investigate isolation effectiveness on seismic performance of the continuous rigid frame bridge, shaking table test with nine sub-tables on 1/10 scaled reinforced concrete rigid frame bridge specimen was performed. The experimental results demonstrate that isolation devices provide flexibility to transform natural period of the scaled model, and additional it can improve the ability of energy dissipation when lead is used. The initial first frequency is 8.17Hz for plate-type rubber bearing and 9.12Hz for leading rubber bearing. The plate rubber bearing and lead-rubber bearing are quite sensitive to seismic wave frequency. The use of various isolation devices affects response of the bridge model. The results show that the more difference in the isolation devices, the more difference in response. Moreover, isolation effect of lead-rubber bearing show obviously more advantage than the one of plate-type rubber bearing, especially in controlling responses of the bridge during major earthquakes. © (2013) Trans Tech Publications, Switzerland.