Strength Properties of Cement-Solidified Dredged Sludge Affected by Curing Temperature

Abstract

In this study, unconfined compressive strength (qu) tests were conducted to explore the coupling effect of organic matter content (3.7%, 7.7%, 10.7%, and 13.7%) and curing temperature (18 °C, 36 °C, 46 °C) on the development of early and mid-late strength of cement-solidified dredged sludge (cement-stabilized clay, or CSC). The microstructure of the CSC containing organic matter at different curing temperatures was also analyzed. The results show that qu of CSC decreases with the increase in organic matter content (Co). The strength growth rate of CSC in the mid-late stage (≥14 days) is small when Co ≥ 7.7%, and it is difficult to increase this strength growth rate even if the curing temperature is increased up to 46 °C. There is a cement incorporation ratio threshold of 15% for qu of CSC containing organic matter (Co = 7.7%), which is not affected by curing temperature; increasing the cement incorporation ratio (to 20%) cannot increase qu significantly. The CSC with high curing temperature has more hydration products and higher structural compactness, and it can obtain higher qu in the early and mid-late stages. A high curing temperature can increase the early strength growth rate and shorten the curing age for CSC containing organic matter.