Bate Bate, Chen Xiao, Chen Chao, Ma Hongyan, Zhu Jianfeng, Cao Junnan, Chen Jiakai, Khayat Kamal H, Zhang Shuai
Institute of Geotechnical Engineering, College of Civil Engineering and Architecture, MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China.
Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65401, USA.
Materials (Basel). 2022 Jan 23;15(3):853. doi: 10.3390/ma15030853.
Setting times, as the early-age properties of cement-based materials, are important properties to ensure the quality and long-term performance of engineering structures. To determine the initial and final setting times of cementitious materials, the compressive wave velocity and shear wave velocity of six early-age mortar samples were monitored. Their time evolution curves of Young's modulus, shear modulus, bulk modulus, and Poisson's ratio were then calculated and analyzed. The signature times of the derivatives of the Poisson's ratio evolution curves correlate well with the initial and final setting times, and the remarkably high coefficient of determination values relative to the data from this study are higher than those presented in the current literature. The proposed derivative method on the Poisson's ratio evolution curve is as good as the derivative methods from vs. evolution curves used by prior studies for the estimation of both the initial and final setting times of the early-age properties of cement-based materials. The formation and subsequent disappearance of ettringite of low Poisson's ratio were postulated to cause the initial dip in the Poisson's ratio evolution curves.
凝结时间作为水泥基材料的早期性能，是确保工程结构质量和长期性能的重要性能。为了确定胶凝材料的初凝和终凝时间，监测了六个早期砂浆样品的压缩波速度和剪切波速度。然后计算并分析了它们的杨氏模量、剪切模量、体积模量和泊松比的时间演化曲线。泊松比演化曲线导数的特征时间与初凝和终凝时间有很好的相关性，相对于本研究的数据，显著高的决定系数值高于当前文献中给出的值。所提出的基于泊松比演化曲线的导数方法与先前研究中用于估计水泥基材料早期性能初凝和终凝时间的基于纵波波速（vs）演化曲线的导数方法效果相当。低泊松比钙矾石的形成和随后的消失被假定为导致泊松比演化曲线初始下降的原因。
