Impact of MgCl2 on the mechanical properties of alite pastes at mesoscale and nanoscale

• DOI: 10.1111/jace.19810
• Publication Date: 2024-04-08T17:54:15Z
• Authors: Yanjie Sun; Yong Tao; Roland J. M. Pellenq; Chi Sun Poon
• Keywords: Brucite; Portlandite

Abstract While the MgCl 2 mixing alite paste causes degradation of modulus and hardness C–S–H formed, underlying mechanism needs to be better understood. This study comprehensively analyzed mechanical properties pastes mixed with solutions, examining effects at both mesoscale nanoscale. The in situ X‐ray diffraction analysis revealed that formation brucite occurred a very early age together portlandite, which may induce loosened packing density C−S−H served as primary cause degradation. We used Bayesian statistical models fit nanoindentation data C−S−H. By extrapolation fraction equal unity, we were able extract elastic (modulus hardness) nanograins. nanoscale showed no significant alterations nanostructures. Atomistic simulations also suggested Mg 2+ ions preferably substitute interlayer Ca rather than intralayer C−S−H, docking CSH induced modest volume contraction.