An Experimental Study on Evaluation of Shear Strength Parameters for Controlled Low-Strength Material
Authors :- Dalal, P.H.; Patil, M.; Iyer, K.K.R.
Publication :- Proceedings of the Indian Geotechnical Conference (IGC 2024), Volume 4. IGC 2024, Lecture Notes in Mechanical Engineering, Springer, 2025
Controlled low-strength material (CLSM) is a low-cost and eco-friendly alternative to self-consolidating backfill, with an expected 28-day strength of less than 8.3 MPa. CLSM has a unique property; it flows like liquid and later sets up like a solid, making it suitable where the placement and compaction of conventional backfill material is difficult. Researchers have tried to develop CLSM utilizing different waste materials with a focus on unconfined compressive strength, while the effect of confinement on the performance of CLSM remains less explored. In this view, authors have evaluated the flowability, hardening time, unconfined and confined strength parameters for different CLSM combinations (20% binder material (cement and fly ash) and 80% filler material (sand and pond ash)). The achieved flowability, hardening time, and UCS values are in the range of 200–300 mm, 10–12 h, and 0.6–1.8 MPa, respectively. The shear strength parameters of CLSM are evaluated through unconsolidated undrained triaxial tests to understand the effect of confinement; and 121.66, 88, and 68.75% increments in peak deviatoric stress were observed when the confining pressure is increased from 25 to 150 kPa for 10%, 12.5%, and 15% fly ash content, respectively. Further, the removability modulus has been evaluated to understand the excavation potential of the developed CLSM combinations. The present study findings suggest that sustainable and excavatable CLSM can be developed using pond ash as filler material and fly ash as binder material, for different applications; wherein, the shear strength parameters are noted to improve with an increase in confinement stresses, either at higher depths or due to surcharge loading.