The effect of adding slag, achieved from wastewater sludge incineration in fluidized-bed furnace, on the quality of concrete

Due to a constant increase in generating the amount of sewage waste it is necessary to find an alternative method of its use or disposal. One of such methods can be utilization of sewage sludge in construction materials industry, particularly in concrete technology and other materials based on cement. It allows using waste materials as a passive additive (filler) or also as an active additive (replacement of part of bonding material). The article aims at presenting the analysis of the effect of adding slag, achieved from wastewater sludge incineration in sewage treatment plant, on properties and quality of concrete mix and hardened concrete. Using an experimental method, the researcher designed the composition of the control concrete mix, which was then modified by means of slag. For all concrete mixtures determined – air content with the use of pressure method and consistency measured by the use of concrete slump test. For all concrete series the following tests were conducted: compressive strength of concrete after 7, 28 and 56 days of maturing, frost resistance for 100 cycles of freezing and thawing, water absorption. The use of slag, ground once in the disintegrator, causes a decrease of in compressive strength of concrete samples in relation to the control concrete series as well as bigger decrease in compressive strength after frost resistance test.