Fly Ash from the Thermal Transformation of Sewage Sludge as an Additive to Concrete

Concrete is the most commonly used structural material, without which it is hard to imagine modern construction works. It is a material that can be substantially adapted to specific operating conditions. To exploit its potential, it is necessary to modify the material composition of concrete. The paper presents the results of research on the impact of modifying concrete with fly ash from the thermal transformation of sewage sludge in the amount of 5, 10, 15, 20 and 25% of cement mass on selected parameters of the C20/25 ordinary concrete. In the course of experimental work, compressive strength measurements were made at two stages of curing. The collected research results enabled us to develop material models describing the impact of concrete input parameters on its compressive strength. The obtained results confirm that it is possible to manufacture ordinary concrete modified by fly ash from thermal transformation of municipal sewage sludge. It was established that the average compressive strength of concrete containing 25% of ash amounts to 41.4 MPa and 44.0 MPa after, respectively, 28 and 56 days of curing.