Analysis of physical and mechanical properties of lightweight aggregate modified with sewage sludge

Abstract

In recent years an increasing activity of sewage sludge management strategy is observed. This is due to EU legislation in the field of environmental protection, which constrains depositing this kind of waste. Sewage sludge is an organic-mineral material separated during the wastewater treatment. Because of physico-mechanical properties of the sewage sludge and the threat it can pose to human health and the environment, it has to be carefully processed before it is ultimately disposed of. In practice, there exist two directions of treatment of sewage sludge: natural management, which is covered by strict legislation, and combustion, which has certain advantages and disadvantages. Due to the above-mentioned legislation and EU standards in the field of environment protection, the sewage sludge management has become a major economical, ecological and technical problem. Thus, it is necessary to search for new methods of its utilization, independent of the present solutions. One of the method of utilization of the sewage sludge is production of the lightweight aggregate as a swelling agent, which creates the porous structure of the ceramic material during sintering. This paper presents the study of the basic physical and mechanical properties of lightweight aggregate derived from sewage sludge and clay. The aggregate was obtain in the forming method and sintering in 1150°C. Evaluation of physical properties was conducted on the basis of parameters such as specific density, bulk and volumetric density, porosity, water absorption. Mechanical properties of the aggregate was determined on the basis of resistance to crushing, abrasion in the Los Angeles drum, and frost resistance. Moreover, the removal of heavy metals from the extracts of aggregates was determined. The obtained results show that the lightweight aggregate with addition of sewage sludge meets the basic requirements for materials used in construction.