Title: Performance of Structural Concrete Using Waste-to-Energy (WTE) Combined Ash

Author(s): Tian

Publication: Web Session

Volume: ws_S22_Tian.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
In the U.S., Waste-to-Energy (WTE) powder plants generate about seven million tons of mixed bottom ash and fly ash (combined ash) annually, which are disposed of in landfills after metal separation. The as-received combined ash waste separated into three fractions: fine (<2mm), medium (2-9.5mm), and coarse (9.5-25mm). This study first assessed the effect of using coarse and medium combined ash as a substitute of mined stone aggregates on the mechanical properties and leachability of concrete. The substitution of up to 100wt% of stone aggregate by the coarse and medium fractions of combined ash produced concrete with compressive strength exceeding 28 MPa after 28 days of curing. This study second discussed the utilization fine combined ash in cement mortar based on the results of mechanical properties, workability, and leachability: (i) fine combined ash can be directly used as sand substitute up to 50vol.% (37wt%); (ii) ground fine combined ash powder can be used as cementitious supplementary material with up to 25vol% (24wt%) substitution of Portland cement. The mechanical tests were supplemented by XRD and SEM analysis to investigate the transformation. The leachability tests by EPA Method 1313 showed that the optimal cement mortar and concrete products effectively immobilized the heavy metals in the combined ash.