Porous alkali-activated materials based on municipal solid waste incineration ash with addition of phosphogypsum powder

Abstract

This is a study of municipal solid waste (MSWI) ash from the Lithuanian incinerator, which was used as an aluminosilicate precursor and pore-forming agent for the production of porous alkali-activated materials. The relationships between the density, pore size, pore distribution, compressive strength, mineral composition, thermal conductivity, and incorporation of phosphogypsum (PG) and/or hydrogen peroxide were observed. It was found that the porous materials had density in the range of 833 kg/m3 − 1345 kg/m3, compressive strength was in the range of 1.5 MPa − 4.1 MPa and thermal conductivity varied in the range of 0.23 W/(m⋅K) − 0.39 W/(m⋅K). The additional pore forming agent hydrogen peroxide with PG has a positive effect on the formation of small pores in the alkali-activated MSWI ash system. In this case, without PG, the number of large pores increased due to coalescence. The addition of PG acted as a binding accelerator of the alkali-activated system and this resulted in the formation of a large number of small and medium sized pores. The prepared porous alkali-activated MSWI ash had the best results with the incorporation of 15% phosphogypsum. In this case, the samples had a compressive strength of 1.8 MPa, the density reached 900 kg/m3 and the thermal conductivity was 0.23 W/(m⋅K).