The Study on the Improvement in Cementitious Properties of Water Treatment Residue and Bottom Ash by Geopolymerization and Autoclave

Abstract

This study was conducted to investigate the feasibility in using water treatment sludge (WTS) and bottom ash (BA) from incineration plant as substituted cementitious materials at 10 and 20 percentages by weight of Portland cement (OPC). The pozzolanic reaction between WTS and BA slightly occurred at 28 curing period with normal curing conditions. WTS, BA and their mixtures, sources of aluminosilicate compounds, were precursors in producing geopolymer with alkaline solution of 10 M sodium silicate (Na2SiO3) and 15 M sodium hydroxide (NaOH). BA was more reactive in polymerization than WTS because of an amorphous
structure. In addition, autoclaving at 210 °C and 2 MPa for 3 hours caused the blended cement and autoclaved BA mortar reaching the minimum 75 percentages of compression strength of pure OPC mortar since the 7 days of curing period whereas autoclaving WTS was not an effective pretreatment for the improvement in cementitious properties .