Some Insight into Effects of Primary Curing Conditions on the Strength Development of Soils Treated with Paper Sludge Ash-Based Stabilizer

Abstract

The utilization of Paper Sludge Ash-Based Stabilizer (PSAS) presents an innovative method for incorporating eco-friendly materials derived from industrial processes into construction ventures. PSAS is crafted by immobilizing heavy metals found in the initial ash particles of paper sludge (PS), a byproduct stemming from the incineration of PS in paper mills. This study was undertaken to explore the impact of primary curing conditions and subsequent crumbling on the physical attributes, compaction properties, and strength characteristics of soils treated with PSAS. To draw comparisons, a parallel investigation was conducted on soils treated with Blast Furnace Cement Type B (BFCB) and Quick Lime (QL). Following a secondary curing phase in a saturated environment, cone index tests were performed on samples treated with PSAS, BFCB, and QL. The findings revealed that the cone indexes of samples subjected to primary curing exhibited variations, either higher or lower, in contrast to those without primary curing. These discrepancies were contingent on the primary curing environment and the duration of the curing period. These divergent trends were attributed to the interplay of “strength reduction due to crumbling” and “strength augmentation attributed to reduced water content during compaction.” In cases of PSAS-treated soils demonstrating gradual strength development, pre-compaction adjustment of water content in treated soils through primary curing proved to be a viable strategy. Furthermore, to minimize disparities between on-site observations and laboratory findings, we recommend aligning the curing conditions in the laboratory mixture design with real-world field conditions.