Understanding the microstructural evolution of hypersaline cemented paste backfill with low-field NMR relaxation

Cemented paste backfill (CPB) comprising mineral tailings, binders and mixing water is an important potential support material in the mining industry. As mechanical properties of CPB are significantly influenced by its microstructural characteristics development measurement tools to better understand pore structure evolution for increased utilisation. This study reports application low-field nuclear magnetic resonance (NMR) relaxation time measurements characterise materials over 56 days hydration, contrasting common tap hypersaline (~22 wt% salt) as water. Distinct NMR populations were evidenced within each sample, revealing presence both capillary ( T 1,2 ≈ 10 ms) gel 300–500 μs), with time-dependent facilitating characterisation hydration period assessed. Hypersaline samples demonstrated a time-lag this measured evolution, relative those hydrated water, while rates observed increase binder content. Further, 1 2 times found correlate uniaxial compressive strength investigated, formulation predictive correlation function between properties. • Microstructural CPB, prepared monitored using relaxometry. compared via UCS tests results slower structural lower strength.