Publications by authors named "Zhengyi Ren"

Steel slag is a solid waste produced in crude steel smelting, and a typical management option is stockpiling in slag disposal yards. Over the years, the massive production of steel slags and the continuous use of residue yards have led to vast occupation of land resources and caused severe environmental concerns. Steel slag particles can potentially be used as aggregates in concrete production.

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Article Synopsis
  • This study evaluates concrete damage using the acoustic emission (AE) technique combined with digital image correlation (DIC) during compressive loading tests.
  • The research found a strong relationship between AE elastic wave velocity and stress, with minimal influence from the size of the concrete specimens or the characteristics of coarse aggregates.
  • The damage process was categorized into three stages based on the standard deviation of AE elastic wave velocities, suggesting that this method could be a reliable and non-destructive way to assess concrete damage during compression.
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The size of the fracture process zone (FPZ) has significance for studying the fracture mechanism and fracture characteristics of concrete. This paper presents the method of assessing the FPZ of Mixed-Mode I-II for quasi-static four-point shearing concrete beams with pre-notched by Lagrangian strain profiles from digital image correlation (DIC). Additionally, it explores the influences of volume rates of the coarse aggregate of 0%, 28%, 48%, and 68%, and the specific surface areas of 0.

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A miniature reflectron time-of-flight mass spectrometer (TOF MS) with orthogonal extraction coupled with electron impact (EI) ionization source can be used to perform in situ gas composition analysis in a planetary environment. However, performances such as the mass resolution, sensitivity, limit of detection, mass range, and mass accuracy are often decreased because of miniaturization. Herein, a compact instrument for space applications has been developed, and its performance has been evaluated.

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