New solidification technology and mechanical properties of municipal sludge

Municipal sludge production in China is huge, and will seriously affect the comprehensive management of the environment if not handled properly. To investigate an efficient, resourceful and stable municipal sludge treatment technology, in this study, the municipal sludge is first subjected to quicklime digestion treatment, and then orthogonal test. Taking the unconfined compressive strength as the index, the optimum ratio of raw lime, soil, municipal sludge and curing agent are selected. Using this ratio, a new type of municipal sludge solidified soil is prepared and its mechanical properties are discussed. The test results show that the new municipal sludge curing agent has a good effect on the treatment of municipal sludge and the heavy metals leaching amount meets the national standard requirements. The strength of sludge solidified soil increases with the increase of curing age, and it tends to be relatively stable after 28 days. In addition, alkali has a promoting effect on the strength, and it is suggested that the initial formulation of the solidified soil is controlled to be between 45% and 50%. Furthermore, in the triaxial shear test, the stress peak and structural yield stress increase with the increase of confining pressure and curing age. In the ring shear test, the residual strength is proportional to the curing age and effective normal stress, and inversely proportional to the shear displacement.