Mingjiang Tao副教授讲座通知
报告人：Mingjiang Tao副教授
单位：Worcester Polytechnic Institute, USA.
题目：Next Generation Sustainable Cementitious Material (Geopolymer) − Synthesis, Characterization and Modeling and its applications in Geotechnical Engineering
地点：新实验楼211
时间：2017年7月3日下午15:00-16:00
报告简介：
Geopolymer has received increasing interest as a promising sustainable alternative to ordinary Portland cement (OPC) because of its high strength, low cost, low energy consumption and CO2 emissions during synthesis. However, the relationship among the synthesis, geopolymerization process, microstructures, molecular structures and mechanical properties of geopolymers remains poorly understood. To fill this knowledge gap, geopolymers’ mechanical properties at nano-scale were characterized through grid-nanoindenation technique while the polymerization process and molecular structure of geopolymer gels were revealed through reactive molecular dynamic simulations.
Four phases (e.g., porous phase, partially developed geopolymer gels, geopolymer gels and unreacted metakaolin or crystals) and their nano-mechanical properties were identified in metakaolin based geopolymers (MKG) with grid-nanoindentation technique. It was found that the proportion of geopolymer gels largely determines the mechanical strength of the resulting geopolymers while other factors (e.g., pores and cracks) also play some roles in macro-scale mechanical strength of geopolymers. The computationally polymerized molecular structures of geopolymer gels were obtained. The distribution of Si4(mAl) and radial distribution functions of Si-O, Al-O, O-O and Na-Al for the models were compared and qualitatively agreed well with the experimental results from nuclear magnetic resonance (NMR) and neutron/X-ray pair distribution function in previous literature. Three polymerization stages: oligomerization, ring formation and condensation, were identified based on the nature of polymerization process, which were found to be affected by the simulation temperature and Si/Al ratio. A higher temperature enhanced the reaction rate while a lower Si/Al ratio resulted in more compact geopolymer networks.
The results from the studies on the use of geopolymer for stabilization soils, including sulfate-rich expansive ones, will also be discussed.
报告人简介：
Mingjiang Tao
Associate Professor & Interim Associate Department Head, Department of Civil & Environmental Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, USA, taomj@wpi.edu.
Mingjiang Tao received BS in civil engineering from Fuzhou University, China in 1997 and a MS in geotechnical enigneering from Tongji University, China in 2000, and Ph.D. in civil engineering from Case Wester Reserve University, USA, in 2003, respectively. He joined Worcester Polytechnic Institute in 2007, where he is an Associate Professor and Interim Associate Department Head of civil engineering. He is the author of more than 45 papers on alternative cementitious binders, asphlat concrete, granular materials, and characterization of construction materials at nano- and marco-scales. His research has been funded by the National Science Foundation, Federal Highway Administration, state departments of transportation, and New England Transportation Consortium. Prof. Tao is a Member of the American Society of Civil Engineers and member of Chemical and Mechanical Stabilization Committee (AFS90), Engineering Behavior of Unsaturated Soils Committee, and Physicochemical and Biological Processes in Soils (AFP40) of the Transportation Research Board, and member of Sigma Xi.
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