*Proceeding Paper* **Physico-Chemical Properties of Sewage Sludge Ash and Its Influence on the Chemical Shrinkage of Cement Pastes †**

**Marcin Adamczyk \* , Tomasz Zdeb and Tomasz Tracz**

† Presented at the 10th MATBUD'2023 Scientific-Technical Conference "Building Materials Engineering and Innovative Sustainable Materials", Cracow, Poland, 19–21 April 2023.

**Abstract:** According to European Union regulations regarding the storage and disposal of industrial waste, waste generated during the treatment of municipal sewage should be managed in an environmentally friendly manner. In order to reduce environmental risks and minimise volume, sewage undergoes thermal treatment. The resulting ash contains toxic components, so it is essential to properly dispose of it. For this reason, the possibility of utilising this type of waste in cement composites has been subject to preliminary verification. To this end, so far, basic tests regarding the parameters such as water demand and setting time have been performed for cement pastes containing ash from the incineration of sludge produced from municipal sewage (Sewage Sludge Ash—SSA). The main purpose of this article is to describe the chemical shrinkage of cement pastes containing this additive. CEM I Portland cement and fly ash obtained at the Thermal Sludge Disposal Station at the Płaszów Sewage Treatment Plant were used in this study. Cement was replaced with ash in the rates of 10%, 20%, and 30%. The results confirm that with an increase in the SSA additive, a reduction of chemical shrinkage of 9.5%, 21.4%, and 31% is observed at 10%, 20%, and 30% content of the additive, respectively. The presented results confirm the possibility of using this material as a cement replacement in cement composites.

**Keywords:** sewage sludge ash (SSA); cement pastes; chemical shrinkage
