Influence of Spent Tea as a Partial Cement Replacement on the Mechanical Performance of Cementitious Clayey Soil

Abstract

This study investigates the stress-strain behavior and mechanical performance of cementitious materials incorporating spent tea as a partial cement replacement. The unconfined compressive strength (UCS) of the samples was evaluated at 7 and 28 days under varying water-to-binder (w/b) ratios (1.0, 1.2, and 1.4) and tea replacement levels. Results indicate that UCS increased with curing time, highlighting the continued hydration and densification of the cementitious matrix. At 7 days, specimens exhibited lower peak stresses, particularly at higher w/b ratios, due to increased porosity and delayed hydration. By 28 days, UCS improved across all replacement levels, though higher tea dosages (more than 6%) exhibited strength reductions due to the dilution of cementitious materials and organic interference with hydration. Optimal strength performance was observed at 3% tea replacement, suggesting potential nucleation or filler effects. The influence of w/b ratio was significant, with lower ratios (1.0) yielding superior strength due to reduced porosity and enhanced matrix densification. Conversely, higher w/b ratios (1.2 and 1.4) led to strength declines due to excessive water-induced pore formation. Overall, spent tea shows promise as a sustainable partial cement replacement, but optimal dosage and mix design are critical to maintaining structural integrity and mechanical performance.