This study reviews the characteristics of municipal solid waste incineration (MSWI) ashes, with a main focus on the chemical properties of the ashes. Furthermore, the possible treatment methods for the utilization of ash, namely, separation processes, solidification/stabilization and thermal processes, are also discussed. Seven types of MSWI ash utilization are reviewed, namely, cement and concrete production, road pavement, glasses and ceramics, agriculture, stabilizing agent, adsorbents and zeolite production. The practical use of MSWI ash shows a great contribution to waste minimization as well as resources conservation.

https://www.mdpi.com/2071-1050/2/7/1943/pdf

Use of incineration MSW Ash: A Review

Combined use of MSWI bottom ash and fly ash as aggregate in concrete formulation: environmental and mechanical considerations.

Recycled powder (RP) is the main by-product in the reclamation of construction and demolition (CD in addition, improvement methods and a benefit evaluation of RP concrete are further introduced. Based on statistical data that describe the activity index of RP and the compressive strength of RP concrete, the median diameter and replacement ratio of RP in concrete preparation should be below 30 μm and 30%, respectively. The use of RP improves the durability of concrete when the RP fineness is superior to the cement fineness. Increasing the RP fineness is an effective approach to improving the properties of RP concrete, and a CO2-curing treatment of RCP is an eco-friendly modification method. Furthermore, the use of RP in concrete has good economic and environmental benefits. Therefore, one expects that this review helps the further use of RP in concrete.

The utilization of eco-friendly recycled powder from concrete and brick waste in new concrete: A critical review

The past and future of sustainable concrete: A critical review and new strategies on cement-based materials

Municipal solid waste incineration (MSWI) bottom ash has gained increasing attentions for its friendly application worldwide, due to promotion of waste recycling One of the biggest concerns for incineration bottom ash (IBA) utilization lies in its elevated metal concentrations and leaching potential While challenges faced by the user are miscellaneous based on several aspects—regulations and rules, the heterogeneity of IBA sources, specific risks arisen from individual applications and/or mixed public views, etc Extensive knowledge on IBA characterization, existing treatment and application contributes to optimize life cycle of the bottom ash, herein enhancing the IBA management practices On the understanding that both feedstock and the process for incineration are various, properties, treatments and applications of the IBA are accordingly different Nevertheless, literature reviewed data indicate evidently that IBA, varying in its original resources and treatment facilities though, shares common geotechnical and chemical properties As the technology development on the IBA is dominated by these common properties, through which the proper treatment and application could be well determined In this review three perspectives were concentrated First, general properties of IBA eg heavy metals and their leaching potential, bulk components, particle size distribution and pH were investigated, whereby the general trends were indicated with collective plots Secondly, the existing status quo on IBA treatment methods and applications were investigated, suggesting a highest potential as low-strength aggregates Thirdly, toxicity studies and LCA on IBA as emerging research topics were also investigated, to further justify its application feasibility

Review of MSWI bottom ash utilization from perspectives of collective characterization, treatment and existing application

Concrete possessing high-passing ability needs to be flowable and cohesive. Hence, passing ability cannot be improved by solely adding superplasticizer, which increases both flowability and segregation of concrete simultaneously. Decreasing the maximum size of aggregates so that concrete segregates at lower cohesiveness is a possible but undesirable way as it narrows the aggregates' grading and decrease dimensional stability of concrete. With the same maximum size of aggregates, passing ability can be improved by raising the concurrent flowability-segregation envelope of concrete. In this paper, fly ash and silica fume (cementitious fillers) and limestone (inert filler) were selected to replace cement partially and subsequently the passing ability of concrete was studied. From the results, it was evident that when either type of fillers were used, the passing ability and maximum limits of flowability and segregation achieved simultaneously increase. It is because these fillers are finer than cement that provides better filling effect to increase packing density and excess water leading to better flowability. Concurrently, the cohesiveness of concrete also increases as the content of fine particles increases. These allow concrete to hold the coarse aggregates more firmly when passing through narrow gaps, after which the concrete will keep flowing rapidly.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/suco.201800047

Fillers to improve passing ability of concrete

Utilization of municipal solid waste bottom ash and recycled aggregate in concrete

Third generation polycarboxylate-based superplasticiser (SP) can easily extend the maximum concurrent design limits of strength and flowability of concrete or cement paste, but simultaneously creates unfavorable dilatancy (or shear thickening) that decreases mixing efficiency and pumping range of concrete. The dilatancy is created initially by clustering of free and adsorbed polymers of SP, but further addition of SP can conversely mitigate the dilatancy by improved wet packing density. Because of the negative correlation of packing density and dilatancy, it is believed that partial replacement of cement by finer pozzolanic or inert filler can decrease the dilatancy via improved filling effect. Herein, the dilatancy of cement powder paste with or without pozzolanic fly ash or inert limestone powder replacing partial cement was studied using a coaxial rheometer. The results revealed that there exists a threshold limit of SP, beyond which the effect on dilatancy reverses. At a given SP dosage, partial cement replacement by either filler decreases dilatancy via improved packing density up to an optimal ratio, after which the dilatancy increases because the packing density reverses.

Lucija Hanzic

Papers

Fillers to improve passing ability of concrete

Utilization of municipal solid waste bottom ash and recycled aggregate in concrete

Dilatancy mitigation of cement powder paste by pozzolanic and inert fillers

Cause and mitigation of dilatancy in cement powder paste

Interdependence of passing ability, dilatancy and wet packing density of concrete