Effects of sewage sludge ash and stone powder on the properties of a silt

Abstract

This paper first ever investigates an extensive series of experimental studies on the stabilization of silty soil by incorporating simultaneously two waste materials, which are sewage sludge ash (SSA) and stone powder (SP). Numerous geotechnical characteristics of the soil were investigated by employing four different mixing ratios of SSA and SP additives, namely 5 %, 10 %, 15 %, and 20 % by dry weight. To demonstrate the influence of these waste materials on the geotechnical properties of silt, Atterberg's limits, compaction, unconfined compressive strength, swelling, and fall cone tests were conducted on the specimens prepared. Testing results indicated that the consistency limits were significantly affected (with a range of 30-50 %) by the inclusion of both waste materials. The use of 5 % of each additional material (i.e. S-SSA5-SP5) results in a 22 % increase in the shear strength of clean soil because of pozzolanic-like chemical reactions between the components. The energy absorption capacity of the clean silt has increased up to 70 % by adding waste materials. Furthermore, the utilization of a well-developed multiple regression model was found to enable the precise estimation of undrained shear strength with a notably high level of accuracy (R2 = 0.98).