THERMALLY TREATED SEWAGE SLUDGE AS A POTENTIAL POZZOLANIC ADDITIVE IN CEMENT-BASED COMPOSITES

Nowadays, due to the rapid development and economic growth, the construction industry brings high demands on concrete and cement clinker manufacturing. With the clinker production, high amounts of CO2 emission and required energy are associated. Additionally, there is a large amount of natural resources used to produce the vast volume of concrete annually. To reduce these harmful secondary effects on the human society and environment, there is a need to find an alternative way to develop construction materials from different sources, including wastes and industrial byproducts. In this paper, the potential use of thermally treated sewage sludge in cement based composites mix design is studied. First, chemical analysis of thermally treated and milled sewage sludge is done using XRF device. The particle size distribution is measured on a laser diffraction principle. Frattini method is used for determination of pozzolanic activity. There are investigated also basic physical properties of sludge as matrix and powder density. Treated sludge is used as an addition to Portland cement by 10, 20 and 30 wt% of cement to preparation of cement-based composites. For the developed composite mixtures, basic physical and mechanical properties are measured. Among the basic physical properties, bulk density, matrix density and total open porosity are investigated. The mechanical properties are measured using standard procedures for compressive strength, flexural strength and dynamic Young's modulus assessment. Obtained results indicate that addition of thermally treated sludge to cement and sand in composite mixtures provides construction material which can be produced with the both economic and environmental benefits, including reduction of CO2 emission.