Nanometric structure, fractal nucleation and supercooled water in long aging cement matrix revealed by quasielastic and inelastic neutron scattering

摘要

Understanding the state of hydration water in cements, the dynamics of water confined in nanopore structures, and the two-step dynamic process similar to the one in glasses and known as beta- and alpha-relaxation is a topic of high fundamental interest in condensed matter physics. QENS and INS experiments on hydrated cement pastes after a long aging time were performed using the TOF spectrometer DIN 2PI at IBR-2 reactor, JINR Dubna. Our experimental results confirmed the conclusions of the recent theoretical and MD simulation papers on the existence of supercooled water confined in the matrix structure of cement. A wave vector transfer Q dependence of the dynamic structure factor S(Q,epsilon) at constant energy transfers epsilon velence h(omega) revealed a nanometric structure where the water molecules were trapped in the nanoporous matrix. The relaxation dynamics suggested the existence of a fractal process.