Controlled low strength material modified with lignosulfonate

Controlled low-strength materials (CLSM) have been used for conventional backfilling and structural filling owing to their flowability, self-consolidating, and self-leveling features. This study investigates the rheological, mechanical, and dynamic characteristics of lignosulfonate-modified CLSM. The elemental analysis of lignosulfonate reveals the presence of various elements and an irregular morphology, as observed using a scanning electron microscope. A series of tests, including flow tests, Vicat needle tests, uniaxial compression tests, and shear wave monitoring, are conducted to evaluate the flowability, setting time, strength, and shear wave velocity of lignosulfonate-modified CLSM. The experimental results show that the flowability and initial and final setting times of the CLSM mixtures increase with increasing lignosulfonate content (LC), which improves workability in the field but results in a slight strength loss. Regarding the uniaxial compressive strength, CLSM mixtures with lower LC exhibit a rapid increase in strength during the early stages, while those with higher LC show higher performance on the 14th day of curing. In contrast, an LC of 0.21% led to a slight reduction in the strength on the 28th day. The current study also shows an exponential correlation between the uniaxial compressive strength and shear wave velocity.