Physical and Mechanical Characteristics of Stabilized Construction Sludge for Eco-Friendly Foundation Techniques

During the construction of ground improvement methods such as high-pressure jet grouting and deep mixing in soft ground, cementitious construction sludge (slime) is generated. Although this sludge develops high strength during curing due to its cement-based slurry properties, it is currently disposed of as construction waste, together with other types of sludge (e.g., sewage sludge, wheel-washing sludge, and bentonite mixtures). This practice not only raises environmental concerns, but also leads to increasing social costs. To solve this problem, the objective of this study was to develop an eco-friendly foundation method that utilizes cementitious construction sludge as part of a structural body, rather than treating it solely as waste. To this end, the physical and mechanical properties of sludge specimens were analyzed. Variations in unconfined compressive strength were examined through mix design and strength testing according to the proportions of recycled aggregate and binders. Increasing the recycled aggregate content by 10% resulted in a strength improvement of approximately 155%, whereas a 20% increase resulted in an improvement of approximately 175%. It is concluded that construction sludge generated from ground improvement methods is a viable environmentally friendly and economical alternative for ground structures when properly mixed with recycled aggregates and binders.