Construction Materials, Vol. 6, Pages 82: Effect of Potassium Hydroxide Molarity on the Mechanical and Microstructural Behavior of Sugarcane Bagasse Ash-Stabilized Quarry Sludge

Construction Materials, Vol. 6, Pages 82: Effect of Potassium Hydroxide Molarity on the Mechanical and Microstructural Behavior of Sugarcane Bagasse Ash-Stabilized Quarry Sludge

Construction Materials doi: 10.3390/constrmater6050082

Authors:
Jose Zelaya
Nicolás Pardo
Alexander Méndez
Kelly Quintero

Alkali-activated sugarcane bagasse ash (SCBA) is investigated as a low-carbon chemical stabilizer for quarry sludge (QS) as a preliminary step toward evaluating its potential relative to ordinary Portland cement-based stabilization. In this study, experimental investigations were conducted using a potassium hydroxide (KOH) solution with varying molarities (4 M, 6 M, 8 M, 10 M, and 12 M) while maintaining a fixed SCBA content of 25% in all mixtures. The optimum moisture content (OMC) and maximum dry density (MDD) of the mixtures were initially determined. Subsequently, unconfined compressive strength tests (UCS) and ultrasonic pulse velocity (UPV) were performed on cylindrical specimens (50 mm diameter and 100 mm height) after 7 and 28 days of curing at a temperature of 40 °C. The results indicated that the OMC ranged from 25% (control) to 40% (12 M), increasing with the molarity of the KOH solution, whereas the MDD remained comparatively stable across all mixtures, varying between 1.38 and 1.43 g/cm3 without a clear molarity-dependent trend. The UCS values after 7 days of curing ranged from 0.39 MPa to 1.01 MPa, and after 28 days, from 0.23 MPa to 3.13 MPa. UPV values were in the range of 641.33 m/s to 1332.33 m/s. These results, obtained under accelerated curing at 40 °C, indicate preliminary potential for subgrade or low-demand earthwork applications; validation under ambient curing and comparison with conventional stabilizers remain necessary before broader engineering conclusions can be drawn.