Direct Tensile Measurement for Cemented Paste Backfill

Abstract

Tensile strength is a crucial parameter involved in the design and analysis of cemented paste backfill (CPB). The ability of CPB to withstand tensile forces is essential for the stability of the backfilled stopes, particularly in areas with high stress or deformation. The tensile strength is a critical design parameter used in sill mats to perform underhand cut-and-fill operations. This study presents a novel technique that utilizes rectangular dog-bone specimens and compression to tensile load converters to perform the direct determination of tensile strength. This study indicates that the prevailing assumption regarding the ratio of unconfined compressive strength (UCS) to tensile strength (i.e., 10:1 or 12:1) underestimates the strength. The results suggest a ratio closer to 3:1 or 4:1. The findings indicate that the ratio varies with the curing interval. Specifically, the tensile-to-compressive strength ratios were higher in early-age specimens, as tensile strength values do not increase at the same rate as those of compressive strength. This disparity has notable implications, as underestimating tensile strength via traditional UCS-to-tensile strength ratios could potentially inflate binder consumption. Our study underscores the importance of using direct tensile strength measurements to optimize mining operations.