Properties of Mortars Containing Ash from Sewage Sludge Incineration

The incineration of sludge is one of currant methods of its disposal. Considering the chemical and physical properties of sewage sludge ash an attempt was made to introduce it into cement composite as a replacement of Portland cement - active addition. The analogy between the ash from sludge combustion and traditional mineral additions used in cement composites technology was observed. It was found that the ground ash points out the pozzolanic activity. The addition causes the delay of the beginning of the cement-binder hydration process, but it does not prolong the entire setting time. The presence of the ground ash causes the slowdown in the dynamics of the compressive as well as flexural strength development of cement composites but it does not reduce the final strength. The results presented indicate the possibility to reuse the ash from sludge combustion in cement based materials.