Characterization of Wasted Wash-Stone for a Possible Re-Use in Construction Materials

Wasted wash-stone, based on pumice and expandable clay, deriving from textile treatment in industrial laundries is generally land-filled. It is also well known that natural pumice is used as aggregate for manufacturing light-weight concrete. The use of light-weight concrete is becoming more and more relevant due to its lightness and thermal-acoustic insulation properties in accordance with sustainable building principles. The possibility of replacing natural pumice with wasted wash-stone of laundries could lead to a decrease in the waste flux to disposal, to exempt companies from the related taxes and to a reduction in the extraction of non-renewable raw materials from quarries. The results obtained in this work show that the properties of the characterized wasted wash-stone are comparable with those of a commercial pumice used as aggregate to manufacture light-weight concretes. The main negative characteristics of the analyzed samples, in view of a possible re-use as aggregate in concrete, are the low reproducibility and the significant presence of organic substances (congruent to 8%) which could slow down the set time and the hardening process of the cementitious materials. However, the problem could be overcome by changing the sampling point of the waste material in the processing cycle before disposal.