Research on Arch Effect and CFRP Strengthening Effect of RC Beams with Corroded Stirrups

Shuang Chen,Haibo Lyu,Lei Wang,Xin Zhang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

In many cases the corrosion of steel reinforcement is considered to be the main reason that leads to the deterioration of the bond between steel reinforcement and concrete and causes the failure of members. However, stirrups with smaller diameter are more likely to get rusted and it is more difficult to find corrosion expansion cracks on the surface of concrete. Then the function of stirrups to restrict longitudinal bar from slipping will be weakened, which alters the mechanical properties and failure mode of corroded Reinforced Concrete (RC) beams. In this paper, the influence of corrosion of stirrups and the effect of strengthening corroded RC beams with Carbon Fiber Reinforced Polymer (CFRP) sheets were studied. The corrosion rate for each group varied between 0% to 18% which represented mass loss of the longitudinal steel reinforcement on the tension side. The longitudinal reinforcement of beams in Group A was not wrapped by the stirrups in order to simulate the situation that the stirrups were seriously corroded and lost their function. Beams of Group B were corroded control beams. Beams of Group C were corroded and then repaired by applying longitudinal CFRP sheets at the bottom and additional U-shaped CFRP sheets around the cross-section. Test results showed that the corrosion of stirrups had a detrimental effect on strength as well as the bond stress between steel bars and concrete. The mechanical mode of experimental beams tended to act like an arch. The greater the corrosion rate was, the more obvious the arch effect was. In addition, combining longitudinal and U-shaped CFRP sheets enhanced the ultimate load by an average of 56.5% of corroded RC beams. However, because of the longitudinal cracks, the strengthening effect of CFRP was much diminished when the corrosion rate was particularly high.

The role of oxygen species in the selective oxidation of methanol to dimethoxymethane over VOx/TS-1 catalyst

Shuang Chen,Xinbin Ma 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.45 No.-

VOx-based catalysts showed good performance in selective oxidation of methanol to dimethoxymethane(DMM). For VOx/TS-1 catalyst, the experiments of Temperature Programmed Surface Reaction (TPSR), insitu Infrared spectrometer (in situ IR) and X-ray photoelectron spectroscopy (XPS) were carried out toinvestigate the products distribution of the methanol oxidation reaction and the adsorb-desorptionprocess at active centers. Furthermore, the role of oxygen species during the reaction process over VOx/TS-1 catalyst and the surface reaction mechanism was explored.

Experimental study on migration and transformation of selenium species and DFT calculation in WFGD simulated slurry

Shuangchen Ma,Fang Xu,Dao Qiu,Xiangyang Chen,Ruimin Wang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

Selenium is a harmful trace element emitted during the combustion process of coal-fired power plants. Most of the selenium is enriched in the downstream wet flue gas desulfurization system (WFGD). Thisstudy found that S2O28 is the most important factor affecting the oxidation of selenite. In the processof simulating slurry oxidation of selenite to selenate, the presence of S2O28 can increase the oxidationrate of selenate from about 50% to about 80%. At the same time, this study also considered the influenceof selenium concentration, initial pH, SO2 concentration and temperature etc. on the transformation ofselenium species. It was believed that the application of ORP to the indication of selenite oxidation statusneeds further demonstration. Energy Dispersive X-Ray Spectroscopy (EDX) and X-ray photoelectron spectroscopy(XPS) were used to confirm the migration of selenium in the desulfurization slurry to gypsum. Inaddition, DFT calculation was performed to obtain theoretical parameters for the adsorption of seleniteand selenate by gypsum. The results of this study are helpful to understand the transformation andmigration of selenium in the desulfurization system, which provide theoretical support for the realizationof selenium in-situ control.

Experimental and mechanism research on volatilization characteristics of HCl in desulfurization wastewater evaporation process using high temperature flue gas

Ma Shuangchen,Chai Jin,Wu Kai,Wan Zhongcheng,Xiang Yajun,Zhang Jingrui,Fan Zixuan 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

Due to the promulgation of “water pollution control action plan” in China, zero liquid discharge of desulfurization wastewater has become a new trend for water pollution control in power plants. The HCl volatilization in desulfurization wastewater evaporation process is the key problem that may influence the application of evaporation technology, so experiment was carried out in self-made experimental system. The effects of temperature, pH, Cl− concentration, total dissolved solids and main metal ions on HCl volatilization were explored. Results have shown that HCl volatilization increases respectively from 5.42% to 20.43% and 2.22% to 9.18% with the increasing temperature from 180 °C to 380 °C in two kinds of actual desulfurization wastewater evaporation process. When pH < 7, Cl− concentration is the main influencing factor on HCl volatilization; the higher Cl− concentration is, the higher HCl volatilization will be observed. While pH > 7, pH becomes the dominant factor, increasing pH will inhibit HCl volatilization; Mechanism of HCl volatilization was studied simultaneously by XRD and TGA. Gaseous HCl mainly comes from the combination of free H+ and Cl−, hydrolysis of Ca2+ and Mg2+ in liquid phase and hydrolysis of hydrate in high temperature solid phase; Ways to inhibit HCl volatilization in process were put forward according to the experimental results. The use of Ca(OH)2 to adjust the pH of desulfurization wastewater to 9.0–10.0 can inhibit HCl volatilization economically and efficiently. This study provides the key data for the application of flue gas evaporation technology under high temperature. The research results have important theoretical and practical values for the engineering practice of this technology.

Experimental study on FeIICit enhanced absorption of NO in (NH4)2SO3 solution

Bei Yan,Jiehong Yang,Meng Guo,Sijie Zhu,Weijing Yu,Shuangchen Ma 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

FeIICit and (NH4)2SO3 mixed solution was selected as denitrification absorbent, and enhanced absorptionof NO was studied in a bubbling reaction column. The results show that, the highest NO removalefficiency achieved under the molar ratio of FeII to Cit was 1:2, NO removal efficiency decreased slightlywith the increase of pH in the range of experimental pH, the NO removal efficiency reduced with theincrease of temperature. NO removal efficiency increased slightly with the increasing concentrations ofimport NO, but decreased with the increasing gas flow rate. Validated experiment was carried out underthe optimum conditions in the double columns, the NO removal efficiency reached up to 71.66% within1 min and 48.14% within 6 min.

Study on NO enhanced absorption using FeIIEDTA in (NH4)2SO3 solution

Bei Yan,Jiehong Yang,Meng Guo,Gongda Chen,Zhao Li,Shuangchen Ma 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

In order to improve the performance of NO reductive removal using (NH4)2SO3 solution, a mixed solution of FeIIEDTA and (NH4)2SO3 was chosen as absorbing liquid for strengthening NO absorption in the bubbling reaction tower. The mechanism of NO removal using the mixture solution was analyzed, and the species transformation of FeIIEDTA was explored. The effects of pH, reaction temperature, FeIIEDTA concentration, concentrations of NO and SO2 on NO removal efficiency were investigated. The NO removal efficiency can exceed 80% under the optimum experimental conditions.

Blistering of potassium-tantalate single crystals induced by helium implantation

Xiang Bingxi,Han Huangpu,Ma Yujie,Liu Kaige,Wang Lei,Kong Lingbing,Chai Guangyue,Ruan Shuangchen 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.9

Potassium-tantalate crystals were implanted with helium ions at 190 keV and then thermally treated at different temperatures to study their blistering. The surface blistering, hydrogen depth distribution, and lattice damage induced by He+ implantation were characterized using secondary ion mass spectroscopy, optical and transmission electron microscopy, and Rutherford backscattering spectrometry. The blistering of potassium-tantalate crystals was achieved at certain ion fluences followed by thermal treatment.