The immobilisation of heavy metals from sewage sludge ash in geopolymer mortars

Sitarz, Mateusz; Zdeb, Tomasz; Castro-Gomes, João; Soares, Erick Grünhäuser; Hager, Izabela

doi:10.1051/matecconf/202032201026

Cited by 5 publications

(5 citation statements)

References 26 publications

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“…Investigations on the rheological, mechanical and physical properties of AAM were conducted by the authors in their recent publications [ 18 , 19 ]. A microstructure analysis was also conducted [ 20 ], thereby enabling a thorough analysis to be performed on the evolution of properties with time.…”

Section: Introductionmentioning

confidence: 99%

“…The main novelty of the present study consists in the fact that designed materials are able to set at room temperature, with no need of thermal curing, which involves energy savings at the material manufacturing stage [ 4 , 8 , 18 ] The research proved that high-performance materials could be produced, showing an impressive mechanical performance reaching 63.0 MPa at 28 days. Although slag addition improves the mechanical performances of fly ash geopolymer mortar considerably, the durability aspect required investigations.…”

Section: Introductionmentioning

confidence: 99%

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Chloride Ions’ Penetration of Fly Ash and Ground Granulated Blast Furnace Slags-Based Alkali-Activated Mortars

et al. 2021

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Due to the need to reduce the CO2 emissions of mineral binders, researchers are considering the use of alkali-activated materials (AAMs) as an alternative to cementitious binders. The properties of AAMs can be more advantageous than those presented by cementitious binders, and thus they can replace Portland cement binders in some applications. Mechanical tests of AAMs are being conducted on an ongoing basis; however, durability issues related to reinforcing steel in conditions in which steel members interact with chloride ions remain unsolved. In this paper, the precursors for AAM preparations are blends of fly ash (FA) and ground granulated blast-furnace slag (GGBFS) in four slag proportions: 0%, 10%, 30% and 50% expressed as a percent of FA mass. Four alkali-activated mortars were prepared, denominated as AAM 0, AAM 10, AAM 30 and AAM 50, respectively. Their basic physical and mechanical characteristics were investigated, as were their gas transport properties. The nitrogen Cembureau method was applied to determine the permeability of the mortar. The transport properties of the chloride ions were determined using the modified NT BUILD 492 migration test. The comparison of results obtained demonstrated a positive effect of GGBFS addition in terms of an increase in bulk density, permeability, porosity and, at the same time, a reduction in chloride ion penetration. The water absorption tests also provided insight into the open pore structures of mortars. The measurements revealed a strong dependence between fluid transport through the mortars and the water absorption and initial water content of materials.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chloride Ions’ Penetration of Fly Ash and Ground Granulated Blast Furnace Slags-Based Alkali-Activated Mortars

et al. 2021

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“…To overcome these limitations, studies have expanded their outlook from conventional precursors to other types of materials with pozzolanic properties to be used as precursors in the development of geopolymer composites. These alternative precursors can include mine tailings [12,20,21], sewage sludge ash [22,23], municipal solid waste incineration bottom ash (MSWI BA) [24,25], steel slag [21,26,27], and glass waste [28][29][30], all of which are locally available materials in different European regions. The referenced studies have focused on the technical aspect of geopolymer development with little focus on the environmental sustainability perspective.…”

Section: Introductionmentioning

confidence: 99%

Identifying Optimal Precursors for Geopolymer Composite Mix Design for Different Regional Settings: A Multi-Objective Optimization Study

et al. 2023

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Global objectives to mitigate climate change in the construction industry have led to increasing geopolymer development as an alternative to carbon-intensive cement. Geopolymers can have similar mechanical properties and a lower carbon footprint. However, geopolymer production is not as homogeneous as cement because it is produced by synthesizing alkali solutions with different aluminosilicate precursors. This study assessed the feasibility of using conventional (fly ash, blast furnace slag, and metakaolin) and alternative precursors (steel slag, mine tailings, glass waste, sewage sludge ashes, and municipal solid waste incineration bottom ashes (MSWI BA)) in geopolymer mixes for different European regions (Belgium and Finland) from a sustainability perspective, using environmental, economic, and resource availability indicators as the criteria. A multi-objective optimization technique was applied to identify optimal precursors for geopolymer mixes using two scenarios: (1) considering both conventional and alternative precursors; (2) only considering alternative precursors. The results from the first scenario show that one of the most optimal precursor combinations for the geopolymer mix is 50% fly ash, 25% MSWI BA, and 25% sewage sludge ash for Belgium. For Finland, it is 19% fly ash, 27% mine tailings, and 45% MSWI BA. For the second scenario, one of the most optimal precursor combinations for Belgium is 87% MSWI BA and 13% steel slag. For Finland, it is 25% mine tailings and 75% MSWI BA. Subsequently, linear regression analysis was applied to predict the compressive strength of the identified optimal mixes, and the results for Belgium and Finland were between 31–55 MPa and 31–50 MPa for the first scenario and between 50–59 MPa and 50–55 Mpa for the second scenario, respectively.

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“…Furthermore, due to the unique 3D gel network structure of geopolymers, it is easy to solidify heavy metal ions. The use of SSA in the preparation of geopolymer can greatly reduce the pollution risk of heavy metal leaching [10][11][12][13]. Researchers studying geopolymer prepared from a mixture of SSA and other precursors including metakaolin, rice husk ash, fly ash and GGBS have mainly focused on the effects of raw material proportions and alkali activator composition on mechanical properties [9,[14][15][16][17][18][19][20][21], while there is a lack of emphasis on performance, cost and carbon emissions, which are all important factors considered in practical applications.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Evaluation of the Performance and Benefits of SSA–GGBS Geopolymer Mortar

et al. 2023

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The activity of sewage sludge ash (SSA) is not high; ground granulated blast slag (GGBS) has a high calcium oxide content that can accelerate polymerization rates and exhibit better mechanical performance. In order to improve the engineering application of SSA–GGBS geopolymer, it is necessary to conduct a comprehensive evaluation of its performance and benefits. In this study, the fresh properties, mechanical performance and benefits of geopolymer mortar with different SSA/GGBS, modulus and Na2O contents were studied. Taking the economic and environmental benefits, working performance and mechanical performance of mortar as evaluation indexes, the entropy weight TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) comprehensive evaluation method is used to evaluate the geopolymer mortar with different proportions. The results show that as SSA/GGBS increases, the workability of mortar decreases, the setting time first increases and then decreases, and the compressive strength and flexural strength decrease. By appropriately increasing the modulus, the workability of the mortar decreases and more silicates are introduced, resulting in increased strength in the later stage. By appropriately increasing the Na2O content, the volcanic ash activity of SSA and GGBS is better stimulated, the polymerization reaction is accelerated, and the early strength increases. The highest Ic (integrated cost index, Ctfc28) of geopolymer mortar is 33.95 CNY/m3/MPa, and the lowest is 16.21 CNY/m3/MPa, which is at least 41.57% higher than that of ordinary Portland cement (OPC). The minimum Ie (embodied CO2 index, Ecfc28) is 6.24 kg/m3/MPa, rising up to 14.15 kg/m3/MPa, which is at least 21.39% lower than that of OPC. The optimal mix ratio is a water–cement ratio of 0.4, a cement–sand ratio of 1.0, SSA/GGBS of 2/8, a modulus content of 1.4, and an Na2O content of 10%.

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The immobilisation of heavy metals from sewage sludge ash in geopolymer mortars

Cited by 5 publications

References 26 publications

Chloride Ions’ Penetration of Fly Ash and Ground Granulated Blast Furnace Slags-Based Alkali-Activated Mortars

Chloride Ions’ Penetration of Fly Ash and Ground Granulated Blast Furnace Slags-Based Alkali-Activated Mortars

Identifying Optimal Precursors for Geopolymer Composite Mix Design for Different Regional Settings: A Multi-Objective Optimization Study

Comprehensive Evaluation of the Performance and Benefits of SSA–GGBS Geopolymer Mortar

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