This paper investigates the influence of Nano-silica (NS) addition on the consistency and compressive strength development of cemented paste backfill (CPB). Tetraethyl-Orthosilicate (TEOS) was used as the precursor of Nano-silica along with ether-based Polycarboxylate superplasticizer (PCS). Two binder types (Portland cement and Slag-cement) and different amounts of TEOS (0.7–14% by mass of binder) with and without PCS are examined for 3, 7, 14, and 28 days curing time. Uniaxial compression tests for unconfined compressive strength (UCS) determination, slump height measurement, changes in gravimetric water content, and differential thermogravimetric analysis (DTG) were used to assess the influence of NS and admixtures (TEOS-PCS) on CPB performance. The results of this experimental study indicate that the addition of approximately 5% TEOS along with 0.5% PCS (by mass of binder) provide the best compressive strengths that can also be anticipated through the higher amount of calcium silicate hydrate (CSH) on DTG curves. It is also noticeable that the positive influence of NS is more evident when the amount of binder was decreased. The addition of PCS to CPB containing NS improved both the consistency of the mixture and the compressive strength development of CPB.

This experimental study investigates the influence of maple-wood sawdust addition on the mechanical and microstructural properties of cemented paste backfill (CPB). Mechanical properties of CPB were determined by uniaxial compressive strength (UCS) tests and microstructural changes were evaluated by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analysis. Results indicate that the addition of 12.5% maple-wood sawdust (by dry mass of binder) improves the strength development of CPB specimens at later hydration age (91 curing days). However, at a higher maple-wood sawdust content of 14.5%, the UCS showed lower improvement. Moreover, MIP and SEM analysis results revealed that the 12.5% wood filler addition made the CPB material less porous and more compact by increasing the mineral content formed by cement hydration. The positive influence of maple-wood sawdust on CPB was associated with higher binder content (?5%) and mid- to long-term curing times (?56 days).