Impact of Municipal Solid Waste Incineration Bottom Ash as Cement Substitution

In this study, municipal solid waste incineration bottom ash powder (BAP) was utilized as cement replacement to improve the resource recycling of municipal solid waste incineration bottom ash (MSWI BA) in building materials. The impact of BAP as cement substitution and NaOH content on the compressive strength of cement mortars were investigated. The hydration products were tested by using X-ray diffraction (XRD), Fourier infrared spectrometer (FTIR), and thermogravimetry-derivative thermogravimetry (TG-DTG). Additionally, the economic and environmental assessments were evaluated. The results show that the pozzolanic activity of BAP is initially low at 7d but improves at 28d. Using appropriate amount of NaOH to stimulate the activity of BAP, the 28d compressive strength can be improved. The regression equation established by response surface methodology (RSM)-central composite design (CCD) can accurately analyze the 28d and 90d compressive strength of cement mortars. The optimal ratio obtained by RSM-CCD is BAP 23.37% (91.67 g) and NaOH 23.013 g. The BAP showed a certain pozzolanic activity, it can react with Ca(OH)₂ and consume Ca(OH)₂ in the matrix to form Friedel’s salt. Meanwhile, at the optimal ratio, the CO₂ emissions could be reduced by 13.71%.