Material–Medium Performance Transferability of Two Modified Cementitious Grout Systems

The performance of cementitious grouts in a host medium depends on whether advantages identified by material-scale screening remain effective after placement. This study examined material–medium performance transferability in two fly-ash cementitious grouts modified with glass fiber powder (GFP) or sodium silicate and an expansive agent (SS-EA). Eighteen mixes were screened using bleeding ratio, hardened volume ratio, and compressive and flexural strengths at 1, 3, and 7 d. With each candidate’s additive combination fixed, nominal water-to-binder ratios (W/B) of 0.6, 0.7, and 0.8 were assessed in independently prepared confined-sand specimens. Confinement and staged volume–time control were held constant. Mix preferences were evaluated within each grout system under its formulation convention. Both systems selected nominal W/B=0.6 at the material scale. GFP retained this ranking, with relatively high and balanced stable stress responses in both directions. The preferred SS-EA condition shifted to nominal W/B=0.7, with more favorable stress retention and grout body continuity. These outcomes show that balanced fresh-state and hardened properties do not necessarily preserve mix preference in the material–medium system. Material screening followed by medium-specific validation supports selection that connects cementitious material properties with spatial continuity and short-term post-injection stress retention.