| INORGANIC MATERIALS AND CERAMIC MATRIX COMPOSITES |
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| Railway Sleepers and Its Microstructure |
| HUANG Shougang1,2, CHEN Jinjie3, WANG Jianxi4, SUN Guowen5
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1 Key Laboratory of Traffic Safety and Control of Hebei Province, Shijiazhuang 050043, China
2 School of Traffic and Transportation, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
3 Hebei University of Water Resources and Electric Engineering, Cangzhou 061001, China
4 School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
5 School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China |
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Abstract As Kenya′s local aggregates are porous and have a high specific gravity, they bring such problems to the construction of concrete for slee-pers as a large viscosity, big bubbles hard to discharge, and potential durability hazard. To prevent the complications, based on the optimization of polycarboxylate water reducer for high water reducing and low adsorption, three different air entraining agents were selected in the paper to further reduce the viscosity of fresh concrete, and the X-ray computed tomography (X-CT), scanning electron microscopes (SEM) and the bubble spacing tester were employed to characterize the distribution of porous aggregates, the distribution of pores, and the interfacial transition zone (ITZ) between aggregate and cement paste, within concrete after hardening. The results showed that, compared with modified rosin thermopolymer air entraining agent and sodium dodecyl sulfate (SDS) air entraining agent, the addition of triterpene saponin air entraining agent can effectively reduce the viscosity of the fresh porous aggregate concrete and the surface tension of aggregates, significantly improving the appea-rance quality of concrete for sleepers. The result of bubble spacing method showed that the space between bubbles in the hardened concrete is significantly reduced. The X-CT and SEM testing after sleeper core sampling demonstrated well-distributed aggregates in the longitudinal direction and a small amount of pores in concrete, with no macroscopic major defect; the micro-pump effect of micro-pores in porous aggregates, their rough surface with strong mechanical interlock effect, and the "pin" effect of their coarse pores filled with paste, all make aggregates more dense; and the ITZ between aggregate and paste also reduces potential pore connectivity in aggregates to a certain extent.
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Published: 24 December 2020
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| Fund:This work was financially supported by the National Natural Science Foundation of China(51778378). |
| About author:: Shougang Huang is an associate professor at the Shijia-zhuang Tiedao University. He has presided over more than 20 subjects, including Rail Transit Structure Design and Intelligent Construction. He was recipient of Second Prize of Social Science Outstanding Achievement Award in Hebei Province. He has published more than 20 academic books and lectured both and granted many patents. |
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2020, Vol. 34 
