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This study explores the feasibility of using sorted municipal solid waste, namely waste-derived paper ash (PA) and food waste ash (FWA) as partial cement substitute (0–15 %) in both paste and mortar. Although the introduction of PA and FWA into the mortar mix leads to a slight expansion of the blended cement paste, it is still compliant with the requirement of EN 197-1. Notably, PA has a significant impact on both the initial and final setting times of the cement paste, attributed to its high CaO content. On the other hand, FWA demonstrates better promise in term of strength consideration, with a lower extent of 7.2 % reduction compared to the control group at a 5 % cement substitution level. Besides that, the chloride content of the blended cement paste, with up to 15 % PA and FWA substitution, still adheres to the 0.1 % limit outlined in EN 196-2. In terms of environmental considerations, the raw materials of PA and FWA exceed the hazardous waste thresholds for certain elements (As, Zn, Pb, Cr, Cu and Sb) as per UNE EN 12457-4 standards. However, when blended into cement mortar at a 15 % substitution level, these heavy metals exhibit significantly reduced concentrations, meeting the criteria for non-hazardous and even inert waste. In overall, this study suggests that utilizing sorted PA and FWA as cement substitute can offer a sustainable option. Despite observed reductions in compressive strength, these materials hold potential advantages in terms of environmental impact mitigation and waste management.

Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites. [ABSTRACT FROM AUTHOR]

Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.

Lightweight concrete has been adopted to prefabricated elements such as facades, staircases and wall systems in housing projects. Many research have been carried out on production of lightweight panels without using ordinary portland cement. The objective of this experimental study was to develop construction materials applicable to lightweight wall system by using ground granulated blast furnace slag and paper ash, which are industrial by-products. Specifically, we carried out an experimental research on the properties of a lightweight matrix that could have application to lightweight wall systems without involving any use of Portland cement that emits massive amount of carbon dioxide (CO2) from chemical process and burning fuel; the major culprit behind global warming. In this study, we used NaOH alkaline activator to achieve the strength of a ground granulated blast furnace slag-based matrix without using general Portland cement. As a result, the mechanism was uncovered as to how NaOH alkaline activator led to the generation of hydrogen gas through reaction with the unreacted Si of paper ash. In addition, we found that construction materials applicable to lightweight wall systems could be manufactured by using ground granulated blast furnace slag and paper ash, industrial by-products.

Novel ceramics from waste material made of (x) paper ash-(80 - x) cullet-20 kaolin clay (10wt% ≤ x ≤ 30wt%) were successfully synthesized using a conventional solid-state reaction technique. Energy-dispersive X-ray analysis confirmed the presence of Si, Ca, Al, and Fe in the waste material for preparing these ceramics. The influence of the cullet content on the phase structures and the dielectric properties of these ceramics were systematically investigated. The impedance spectra were verified in the range from 1 Hz to 10 MHz at room temperature. The phase of the ceramics was found to primarily consist of wollastonite (CaSiO3), along with minor phases of γ-dicalcium silicate (Ca2SiO4) and quartz (SiO2). The sample with a cullet content of 55wt% possessed the optimum wollastonite structure and exhibited good dielectric properties. An increase of the cullet content beyond 55wt% resulted in a structural change from wollastonite to dicalcium silicate, a decrease in dielectric constant, and an increase in dielectric loss. All experimental results suggested that these novel ceramics from waste are applicable for electronic devices. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an experimental investigation on the number concentration decay and size distribution of polydisperse diesel exhaust particles and paper ash particles in a chamber under still conditions and stirred conditions. The particles were measured with two instruments thus allowing particles from 0.016 to to be investigated. Initial number concentrations were above to allow simultaneous coagulation and deposition of the particles. The experimental results show that both still and stirred conditions are effective in reducing particles smaller than in diameter while stirring additionally reduces the concentration of particles above . A regression method was applied to derive the coagulation coefficients and the deposition velocities from the experimental data. The derived values were in the same range of values as those reported in literature. A statistical analysis shows that there is no significant difference between the coagulation coefficient for still and stirred conditions but the deposition velocity is significantly higher under stirred conditions. Further analysis shows that under still conditions coagulation dominates the concentration decay with over 80% contribution to the total loss rate, whereas under stirred conditions the contribution of coagulation decreases to as low as 20%, after a period of 1500s. [Copyright &y& Elsevier]

Remediation of contaminated soil can be performed by using various techniques, which must be adequately tailored for each specific case. The aim of this research is to critically evaluate the potential use of red mud and paper ash and a combination of the two as immobilization additives for the remediation of contaminated soil from one of the most polluted sites in Slovenia. The proposed procedure involves the preparation of geotechnical composites made from contaminated soil and mixed with 25 wt% of immobilization additives and an optimal quantity of water to achieve consistency, at which maximum compaction according to the Proctor Compaction Test procedure can be achieved. The results reveal a positive, time-dependent trend for the immobilization of potentially toxic elements in the composite with paper ash, because of the formation of the new hydration products with potentially toxic elements. In a composite containing only red mud, potentially toxic elements were immobilized by sorption mechanisms with no general time-dependent trends. The composite with a combination of additives demonstrates the remediation characteristics of both red mud and paper ash. Using this approach excavated contaminated soil, red mud and paper ash can be successfully recycled in the proposed composites, which can be beneficially used in situ for rehabilitation of contaminated sites. Nevertheless, mobilization of some potentially toxic elements at high pHs may represent a limiting factor and has to be taken into the consideration when a combination of red mud and paper ash is used as immobilization additive. • Sustainable remediation of contaminated soil by an immobilization method. • Characterization of red mud and paper ash as an immobilization additives. • Preparation of chemically inert geotechnical composites for fill or embankments. • Environmental assessment and mechano-physical characteristics of composites. • Description of the main immobilization mechanisms in the obtained composites. [ABSTRACT FROM AUTHOR]