Experimental study on compaction characteristics of industrial waste residues solidified sludge after crushing

Abstract

For the crushed and remodeled solidified soil(CRS) which is formed by the crushing and compaction of solidified sludge with high water content by using the composite curing agent contained blast furnace slag, carbide slag, and phosphogypsum, the effects of curing agent content and pre-curing age on the compaction characteristics of CRS were investigated through compaction tests and unconfined compressive strength tests. The result show that the CRS is hard to compact as the increase of the curing agent content and the pre-curing time. As the curing agent content is larger than 150 kg/m³, the effect of the pre-curing age on the compaction characteristics of CRS increases significantly. In addition, the compacted density of CRS increases initially and then decreases with the increase of the unconfined compressive strength(UCS) of the solidified sludge without crushing. Thus, there is an optimal UCS corresponding to the maximum compacted density, which can be treated as one of the reference indexes to determine the crushing time. Besides, it is revealed that the compaction characteristics of CRS are greatly influenced by the amount of free water and adsorbed water that converted into the combined crystalline water in the solidified sludge, as well as the frictional action between the crushed particles. Finally, it is recommended to reduce the amount of curing agent and extend the pre-curing age for projects with a long construction period and sufficient yards. In the opposite, it is suggested to increase the amount of curing agent and shorten the pre-curing age for projects with a tight construction period.

Keywords

sludge solidified soil / crushing and remodelling / compaction characteristics / industrial waste residues