engleski

The influence of particle size distribution of sewage sludge ash and clay on the compressive strength of bricks

Bricks were made from sewage sludge ash (SSA) fired under laboratory conditions at a temperature of 1000°C from sewage sludge (SS) originating from the wastewater treatment plant (WWTP) in Karlovac. Mechanical properties of bricks are influenced by different factors such as texture, particle size distribution, type of minerals and chemical composition of the clay and SSA. Literature results of the fineness analysis of SSA together with the particle size distribution curves show that the material is predominantly composed of fine sand and silt particles, indicating its natural suitability as a filler material in brick production or as a substitute for clay after grinding. The particle size distribution of SSA and clay was determined using Malverns Mastersizer 2000 instrument. The sand content of SSA was slightly higher than that of clay soil, while clay soil contained much more clayey and silty material compared to SSA. The results of the tests showed that the SSA content is the determining factor for the quality of the bricks. An increase in the SSA content leads to a decrease in the compressive strength of the bricks. When up to 20% SSA was added to the bricks, the compressive strength was 38.7 Nmm–2. The conditions for production of good quality bricks are 10% SSA in the moulding compounds and firing at 950°C with a heating rate of 5°C min–1 and the resulting compressive strength was 52.9 Nmm–2. The compressive strength for bricks with 5% SSA was 47.4 Nmm–2, while the compressive strength of the control brick (100% clay) was 50.4 Nmm–2.

sewage sludge ; sewage sludge ash ; particle size distribution ; brick production ; compressive strength

nije evidentirano