PhD thesis by Annemette Kappel
Processed sewage sludge ash (SSA) was used in mortar to partially replace cement. The three processes used to treat the SSA were: milling, acid washing and electrodialytic treatment. The treatments were applied for two purposes: 1. optimizing the performance of the mortar, and 2. to recover the phosphorous available in the SSA.
The main purpose of the experimental work was to unfold the aesthetical and technical potentials of mortar with SSA and processed SSA.
The outcome the practiced based research has both a linguistic and non-linguistic part. The non-linguistic part is represented by four series of physical samples that show how ordinary mortar transforms when different degrees of processed SSA are used as partial cement replacement. The physical output signifies the potentials of using SSA as a resource, whereas the technical and aesthetical potentials are unfolded by correlating the physical output with quantitative measurements of compressive strength and flow value of the mortars.
It is possible to produce mortars with SSA after extraction of phosphorous. The performance of mortars with treated SSA may challenge the practicability of using the materials, as the mortars are significantly different from both mortar with untreated SSA and ordinary mortar. However, the research shows that the potentials are conditioned by the circumstance that the SSA first and foremost was regarded as source for phosphorous, especially the changing colours of the mortars, as these also may broaden the perception of cement based materials normally associated to the grey colour.
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