Municipal Waste Incineration Bottom Ash Research Articles

Preparation and Hydration Properties of Sodium Silicate-Activated Municipal Solid Waste Incineration Bottom Ash Composite Ground-Granulated Blast Furnace Slag Cementitious Materials.

The production of municipal solid waste incineration bottom ash (MSWIBA) is substantial and has the potential to replace cement, despite challenges such as complex composition, uneven particle size distribution, and low reactivity. This paper employs sodium silicate activation of MSWIBA composite Ground-granulated Blast Furnace slag (GGBS) to improve the reactivity in preparing composite cementitious materials. It explores the hydration performance of the composite cementitious materials using isothermal calorimetric analysis, Fourier-transform infrared (FTIR) spectroscopy, XRD physical diffraction analysis, and SEM tests. SEM tests were used to explore the hydration properties of the composite gelling. The results show that with an increase in MSWIBA doping, the porosity between the materials increased, the degree of hydration decreased, and the compressive strength decreased. When the sodium silicate concentration increased from 25% to 35%, excessive alkaline material occurred, impacting the alkaline effect. This inhibited particle hydration, leading to a decrease in the degree of hydration and, consequently, the compressive strength. The exothermic process of hydration can be divided into five main stages; quartz and calcite did not fully participate in the hydration reaction, while aluminum did. The vibrational peaks of Si-O-Ti (T = Si and Al) were present in the material. The vibrational peaks of XRD, FTIR, and SEM all indicate the presence of alumosilicate network structures in the hydration products, mainly N-A-S-H and C-A-S-H gels.

Utilization of Aluminosilicate Industrial Wastes as Precursors in CO2-Cured Alkali-Activated Precast Concrete Pavement Blocks

This research focuses on the utilization of recently investigated aluminosilicate industrial wastes as precursors to produce non-structural precast alkali-activated concrete pavement blocks. For this purpose, conventional blocks (200 mm × 100 mm × 80 mm) were produced using electric arc furnace slag and municipal solid waste incineration bottom ashes as the sole binders. Portland cement and fly ash blocks were produced as references. The blocks underwent a curing regimen comprising thermal, dry, and carbonation curing stages. Control uncarbonated specimens were subjected to dry curing instead of CO2-based curing to evaluate the influence of carbonation on the blocks’ strength development. The specimens were subsequently examined following EN 1338, which is the European standard for assessing and ensuring the conformity of conventional concrete pavement blocks. The carbonated blocks revealed improved mechanical and physical properties in relation to the uncarbonated ones. All blocks met standard dimensions, showed minimal skid potential (most indicating extremely low potential for slip for reporting unpolished slip resistance values exceeding 75), and had enhanced abrasion resistance due to carbonation, showing 30% and 11% less volume loss due to abrasion for fly ash and bottom ash, respectively. Carbonated blocks performed better than non-carbonated ones, displaying lower water absorption (0.58% and 0.23% less water absorption for bottom ash and slag, respectively) and higher thermal conductivity (20%, 13%, and 8% increase in values for fly ash, slag, and bottom ash, respectively). These results confirm the effectiveness of the accelerated carbonation curing technique in improving the block’s performance. Despite the promising outcomes, further optimization of the alkaline solution and carbonation curing conditions is recommended for future research.

Enhancing mechanical performance and durability of high strength mortar with incineration bottom ash via Al2O3 micro-powder: An experimental study

The untreated application of municipal solid waste incineration bottom ash (IBA) in cementitious materials can lead to compromised workability, deterioration of mechanical properties, and compromise durability. This paper examines the potential of utilizing Al2O3 micro-powder (ALMP) to enhance the mechanical performance and durability of cementitious materials fabricated with IBA. This paper focuses on the effect of different dosages of ALMP on the workability, mechanical performance and durability of high strength mortar (HSM) prepared by IBA. In addition, effect of ALMP on the ultrasonic pulse velocity (UPV), dynamic modulus of elasticity (DME) and microstructure of HSM was also investigated. Finally, the micro-mechanical performance of HSM paste was determined via nanoindentation experiment. Our study discovered that the integration of ALMP in HSM contrived with IBA notably amplified the flexural and compressive strengths by ranges of 1.12 %∼9.84 % and 3.78 %∼21.26 %, respectively. Simultaneously, the ALMP improved the UPV by an interval of 3.16 %∼9.49 %, and the DME by a parameter of 9.64 %∼18.69 %. Additionally, we observed considerable lowering of drying shrinkage in HSM by 4.96 %∼28.36 % and decline in the chloride migration coefficient by 7.45 %∼38.75 % due to ALMP's presence. Overall, based on the observed impact of ALMP on HSM's workability, mechanical properties, and microstructure, we suggest 10 wt% as the optimal doping amount for ALMP in HSM. Our investigation puts forward that implementing IBA in place of traditional quartz sand in the preparation of HSM could potentially attenuate energy consumption, carbon emissions, and production overheads. The findings of this study may offer instructive significance for improving the resource utilization of IBA in cement-based materials.

Utilizing municipal solid waste incineration bottom ash and volcanic tuff to produce geopolymer materials

Large volumes of municipal solid waste incineration bottom ash (MSWIBA) are produced annually in China; however, their improper disposal causes serious ecological and environmental problems. This study investigated the feasibility of using MSWIBA and volcanic tuff to produce geopolymers. The effects of the MSWIBA content, silicon–sodium molar ratio, and alkali equivalent on the uniaxial compressive strength (UCS) and bulk density of the geopolymer samples were examined using single-factor and optimization tests. The test results showed that the UCS and bulk density of the geopolymer decreased as the MSWIBA content increased, whereas they increased as the alkali equivalent increased. As the silicon–sodium molar ratio increased, the UCS first increased and then decreased, and the change in bulk density was limited. In the final geopolymer preparation, the MSWIBA content was 17.85%, the silicon–sodium molar ratio was 1.71, and the alkali equivalent was 9.49%. According to X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, and nuclear magnetic resonance analyses, the main phases of the geopolymer under the final preparation parameters were quartz, sanidine, calcite, orthoclase, gismondine, and illite. During the geological polymerization process, a large amount of CNASH gel was generated and attached to the surface of the particles or filled the pores between the particles, resulting in a pore size of 0.01–1 μm. The heavy metals in the geopolymers exhibited a good stabilization effect owing to the CNASH gel. Except for Cd, which posed a medium risk, the remaining heavy metals posed low or no risk.

Research on using municipal solid waste incineration bottom ash for cement-stabilized macadam

Municipal solid waste incineration bottom ash (MSWIBA) is the waste generated by incineration power plants. Because of its low activity, it is an effective way to apply it to cement-stabilized macadam (CSM) in road construction. CSM was prepared using varying proportions of bottom ash (0%, 15%, 20%, 25%, 30%, and 35%) and different proportions of cement (3.5%, 4%, 4.5%, 5%, and 5.5%), respectively, to explore the effects of MSWIBA as fine aggregates on the characteristics of cement-stabilized MSWIBA macadam (CSBAM). MSWIBA was examined in terms of its microstructure, chemical makeup, and physical characteristics. Heavy metal leaching, water stability, splitting strength, unconfined compressive strength, and dry shrinkage were all investigated for CSBAM. The findings demonstrated that there was some cementitious and volcanic ash activity and that the bottom ash had a rough, porous surface. The strength of CSBAM decreased with the increase of MSWIBA dosage and increased with the increase of cement reference. Replacing fine aggregate with MSWIBA reduced the water stability of CSBAM. The water stability was better when the bottom ash dosage was more than 20%. Bottom ash reduced the dry shrinkage strain of cement-stabilized macadam, and CSBAM had better anti-dry shrinkage performance. CSBAM had a curing effect on heavy metals, and the leaching concentration of heavy metals was in accordance with the standard, which had less impact on the environment.

Valorisation of municipal solid waste incinerator bottom ash for the production of compressed stabilised earth blocks

This research centres its attention on the valorisation of incinerator bottom ash derived from municipal solid waste with the aim of producing compressed stabilised earth blocks. Compressed stabilised earth blocks is prepared with 6–12% cement and 10–40% MSWIBA, whose performance is assessed in terms of strength and durability. This includes several properties of compressed stabilised earth blocks, including dry compressive strength, flexural strength, tensile strength, water absorption, wetting-drying cycle, ultrasonic pulse velocity and acid attack. The findings indicate that the inclusion of municipal solid waste incinerator bottom ash as a 20% replacement of soil enhances the compressive strength and ultrasonic pulse velocity of the blocks. Nevertheless, the excessive use of municipal solid waste incinerator bottom ash (beyond 20%) results in an augment of void content and a reduction in compressive strength. The results of the study suggest that the usage of municipal solid waste incinerator bottom ash in the blocks leads to the enhancement of their aesthetic qualities. The study employing scanning electron microscopy indicates an excessive quantity of ettringite crystals in the samples derived from ash of quantity beyond 20%. This is because these samples have higher porosity, which enables the acidic medium to penetrate samples easily and react with the cement hydration products. Hence, though showing less discolouration on the surface, these samples show a significant reduction of compressive strength at the end of the testing regime. Similar results were obtained for the wetting and drying test as well. Therefore, this study recommends a maximum usage of 20% municipal solid waste incinerator bottom ash as a replacement for soil.

A sustainable treatment method to use municipal solid waste incinerator bottom ash as cement replacement

This paper studies the use of municipal solid waste incinerator bottom ash as a supplementary cementitious material in concrete products using an innovative chemical treatment approach. The primary objective is to address emissions associated with waste-to-energy facilities and the heavy reliance on ordinary Portland cement as the primary binder in concrete. The proposed method involves the removal of metallic aluminium from the bottom ash and the subsequent use of the treated bottom ash as a partial cement replacement to produce concrete. Concrete specimens were produced with varying proportions of treated or untreated municipal solid waste incinerator bottom ash, replacing 20%, 35%, and 55% of ordinary Portland cement according to EN 197 European standard for common cement. Moreover, class F fly ash was incorporated in equivalent percentages as a reference supplementary cementitious material, and a control mix was prepared using solely Portland cement. The evaluation encompassed multiple visual and analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and setting time analyses on pastes made with Portland cement, fly ash, and bottom ash. All specimens were evaluated in terms of mechanical performance, namely compressive strength. The chemical treatment process facilitated the release of a significant quantity of hydrogen, a by-product of aluminium oxidization. Consequently, this resulted in significantly reduced formation of gas bubbles in concrete in the fresh state and, therefore, diminished expansion during the setting process. As the proportion of cement replacement with bottom ash increased, a decline in strength was observed. However, this decline was less pronounced when using treated bottom ash, particularly with lower levels of incorporation.

Experimental study on municipal solid waste incineration bottom ash as a component of alkali-activated coal gangue-based geopolymer.

This study explores the potential of municipal solid waste incineration bottom ash (MSWI BA) and coal gangue as precursors for alkali-activated cementitious materials (CG-MBA). An examination of the impact of MSWI BA content, NaOH/Na2SiO3 ratio, liquid-solid ratio, and NaOH concentration on strength and reaction through the application of diverse analytical methodologies. Results demonstrate that CG-MBA offers significant environmental benefits compared to conventional cement. When used as a construction filling material, CG-MBA exhibits a remarkable 74.5 ~ 79.2 wt% reduction in carbon dioxide emissions and 70.6 ~ 77.0 wt% reduction in energy consumption. Additionally, CG-MBA effectively immobilizes heavy metal ions in MSWI BA, with a fixation efficiency exceeding 56.0%. These findings suggest that CG-MBA is a promising sustainable solution for waste management, offering significant environmental benefits while demonstrating effective heavy metal immobilization. This approach contributes to pollution control and promotes environmental sustainability in the construction industry.

FORMING AND PROPERTIES OF GLASSES MADE FROM TWO THAI BOTTOM ASHES

Industrial wastes are often an under-utilized source of raw materials. Bottom ashes resulting from incineration processes can contain various metal oxides, including many commonly used in glass making. This research studied the forming and properties of glasses made from two bottom ashes. Lignite bottom ash (BL) from Lampang, Thailand and a municipal solid waste incinerator bottom ash (BP) from Phuket, Thailand. Both bottom ashes were found to contain significant amounts of SiO2, CaO, Al2O3, and Fe2O3. After ball milling, the ashes were melted without additions, at temperatures from 1300 to 1500°C. The resulting glasses, as confirmed by XRD, were black and fully opaque, a result of the high Fe2O3 content. It was found that the BP glasses were slightly more refractory, had a greater average thermal conductivity of 1.52 W/m·K and a lower coefficient of thermal expansion (CTE) of 6.97x10-6/°C, compared to the BP glasses, which had an average thermal conductivity of 1.39 W/m·K and a CTE of 7.98x10-6/°C. The BL glasses also had a higher average density of 2.88 g/cm3 and a Vickers hardness of 6.29 GPa, compared to the BP glasses, with average values of 2.74 g/cm3 and 6.06 GPa, respectively. The increase of glass melting temperature up to 1450°C tended to improve the observed properties, followed by a decrease at 1500°C. Despite the atypical glass chemistry of the two bottom ashes, they were successfully melted to produce glasses and the measured properties demonstrated suitable potential to warrant further study.

Characterization, pre-treatment, and potential applications of fine MSWI bottom ash as a supplementary cementitious material

With the development of waste recovery techniques, previous research has revealed that coarse fractions of municipal solid waste incineration (MSWI) bottom ash (BA) after proper treatment could be applied in the construction sector, while the fines are seldom recovered in practice and normally landfilled. This study explores the potential application of fine MSWI BA (0–2 mm) as a supplementary cementitious material (SCM) in Portland cement (PC) mixtures. Mechanical and chemical pre-treatment approaches have been designed with various conditions to optimize the treating process. The chemical and mineralogical compositions, as well as the metallic Al content in BA were characterized before and after the pre-treatment. It was found that both methods are effective in removing the metallic Al content in BA, Moreover, BA derived from mechanical treatment exhibited more contribution to the hydration reaction in PC mixtures, as revealed by the amount of reaction products and mineral phases formed in hardened trial mixtures. BA obtained was further partially blended in PC mortars to evaluate the performance as compared to SCMs and inert fillers. It was found that treated BA resulted in a slight retarding effect on the reaction kinetics. Treated BA behaved better than the coal fly ash to contribute to the strength development, while the inclusion of BA did not lead to significant influences on the workability.

Municipal solid waste incineration bottom ash recycling assessment: Carbon emission analysis of bottom ash applied to pavement materials

Inspired by the concept of conserving resources, bottom ash has been increasingly utilized in road construction as a readily available waste material. This study sought to address this gap by quantifying the carbon benefits associated with bottom ash application. Through a comprehensive analysis grounded in life cycle theory, author evaluated the changes in energy consumption and carbon emissions before and after the integration of bottom ash into the road construction process. The analysis employed the raw material production stages of different pavement materials as the system boundary. By determining the optimal amount of bottom ash and calculating the associated values, the study proposed an efficient application scheme for utilizing bottom ash in urban engineering construction projects. The results showed that bottom ash had the least carbon reduction effect in permeable bricks, followed by cement concrete and cement stabilized macadam mixture. The most significant effect was observed in asphalt mixtures. However, energy consumption increased with the addition of bottom ash in asphalt mixtures, whereas it decreased in the other three products. The carbon reduction after applying bottom ash was predicted based on the annual growth rate of urban road construction. Under the premise of maintaining the non-destructive application performance of asphalt mixtures, the optimal carbon reduction benefit for a 20% addition of bottom ash was approximately 17,369.9 tons. In cement-stabilized crushed stone mixtures, the optimal carbon reduction benefit ws achieved with a bottom ash content of 30%, approximately 15,797.7 tons. The practice of utilizing bottom ash in road works was significant in terms of maximising the benefits of carbon reduction.

Hydrological and geochemical properties of bottom ash landfills

In Switzerland, municipal solid waste incineration bottom ash is deposited in open landfills, which leads to its interaction with rainwater and thus the formation of a polluted leachate. This study attempts to provide a better understanding of the hydraulic and geochemical properties of bottom ash landfills by combining field and laboratory investigations. The results show that a bottom ash landfill can be described as a generally unsaturated body with several layers of different grain sizes. Three different water domains with variable hydraulic and geochemical properties were identified in the landfill: (1) zones of preferential flow, (2) a reservoir of mobile porewater, and (3) an immobile porewater reservoir. Preferential flow systems account for approximately 5–10 vol.%. The landfill layering is primarily responsible for the formation of various flow systems during heavy rainfall events. The domains and reservoirs provide variable volumetric contribution to the leachate, depending on precipitation rates and duration of dry periods. Sampling of leachate during heavy rainfall events revealed dilution effects for Na (− 59–61% compared to concentrations prior to the event), Ca (− 44–47%), Cl (− 57–77%), and SO4 (− 35–47%), while pH (+ 7–8%) and concentrations of Al (+ 368–1416%), Cu (+ 7–58%), Cr (+ 29–48%), V (+ 100–118%), and Zn (+ 289%) increased significantly. The findings of this study serve as a basis for the development of a hydrogeochemical model of a bottom ash landfill, which allows better prediction of the future evolution of leachate quality.

Utilization of Municipal Solid Waste Incineration Bottom Ash in Cement-Bound Mixtures

In order to protect the natural resources, it is beneficial for the environment when materials that are not valuable, such as waste or recycled materials, are used in engineering. This article presents laboratory studies on the use of mixtures of incineration bottom ash (IBA) from municipal waste incinerators with natural, fine grain and uniform aggregate in cement-bound layers. The mechanical and engineering properties of aggregates were studied, their usefulness was assessed and possible applications are indicated. The chemical composition of the material was found to be consistent with typical IBA from other incineration plants, and leachability studies were carried out, confirming lack of any environmental impact. The authors’ own mixtures were prepared based on optimal water content and maximal dry densities of solid particles, and the compressive strength was calculated after 7 and 28 days of hardening. The results indicate that replacing natural aggregates with IBA permits an increase in the compressive values for the specimens using the same amount of CEM I 42.5R while improving the frost resistance of cement–aggregate mixtures.

Analysis of pore structure characteristics of MSWI bottom ash micro powder concrete

Municipal solid waste incineration (MSWI) bottom ash is a type of bulk waste. Its potential activity can be better harnessed after it is ground into a fine powder, leading to reduced carbon emissions. This paper investigates the pore structure of MSWI bottom ash micro powder concrete and its impact on mechanical properties. Standard tests were conducted to evaluate the mechanical properties of MSWI bottom ash micro powder concrete with four blending ratios under three water-binder ratios. Subsequently, a mercury intrusion test was performed to determine its internal pore structure characteristic parameters. Remaining specimens from the macroscopic test were sampled, and concrete specimens were observed using a high-power electronic environmental scanning microscope to analyze morphological characteristics at various multiples and curing ages. The results indicate that the pore structure of MSWI bottom ash micro powder concrete is uniformly distributed, displaying good fractal characteristics conducive to subsequent secondary hydration reactions. The inclusion of MSWI bottom ash micro powder increases concrete porosity, leading to a decrease in compressive strength. However, as the curing age increases, the value tends to approach that of ordinary concrete, suggesting that MSWI bottom ash micro powder exhibits potential hydraulicity, albeit with a slow hydration reaction. The observed pattern of MSWI bottom ash micro powder concrete aligns with that of ordinary concrete, wherein higher porosity corresponds to lower compressive strength. The addition of MSWI bottom ash micro powder increases concrete porosity, resulting in reduced compressive strength.

Recycling of municipal solid waste incineration bottom ash (MSWIBA) particles into natural fine sands for sustainable engineering cementitious composites

The manufacture of engineered cementitious composites (ECCs) consumes large amounts of natural fine aggregate. In this study, replacement of the natural fine aggregates in ECCs with municipal solid waste incineration bottom ash (MSWIBA) was found to reduce the consumption of natural river sand and the negative environmental impact of MSWIBA disposal. Previously, scholars have shown the potential of using MSWIBA particles as fine aggregates in concrete, but few scholars have evaluated ECCs with high percentages of MSWIBA powder in place of the natural fine aggregates. This study was conducted to design green ECCs by incorporating MSWIBA (BA–ECCs) to completely replace the natural silica sand with various fibers (PVA, PP and PE) and different fiber volume blends (0%, 0.5%, 1%, 1.5% and 2%) and to evaluate the BA–ECCs based on the fluidities, mechanical properties, microscopic morphologies, pore size distributions and heavy metal leaching capacities. The results showed that the addition of MSWIBA increased the porosities of the BA–ECCs. Compared with those of the control group, the maximum flexural strength of the BA–ECCs with 1.5% fiber doping were approximately 27.75% higher. There were relationships between the compressive strength and flexural strength and between the fiber volume content and strength. Moreover, microstructural observations revealed that the MSWIBA powder interacted strongly with both the matrix and the fibers, and the performance of the MSWIBA powder in the matrix was similar to that of a lightweight aggregate during internal curing. Additionally, fiber agglomeration (winding) at a 2% fiber content reduced the compressive and flexural strengths. The BA-ECCs showed lower heavy metal leaching contents than the MSWIBA, and the concentrations of various heavy metals were below the Chinese standards. Overall, this study could support research on the use of MSWIBA particles to prepare sustainable ECCs and recycle MSWIBA particles.

Use of municipal solid waste incineration (MSWI) bottom ash as a permeable subgrade material: An experimental and mechanism study

ABSTRACT As a traditional method of waste treatment, municipal solid waste incineration (MSWI) has become one of the main methods of urban waste treatment. However, as a byproduct of MSWI, a large amount of MSWI bottom ash is not reused in current practice. This study innovatively posits MSWI bottom ash as an eco-friendly adsorbent rather than a pollutant, exploring its potential application as a permeable subgrade material. The results reveal that MSWI bottom ash exhibits promising properties to serve as a permeable subgrade material to achieve the permeability and improve the sustainability for subgrade. Due to the arrangement of its particles, it shows excellent performance in shear strength and permeability, which are comparable to or surpass those of sandy soils. The average pore width of 14.200 nm allows heavy metal substances to be encapsulated within the matrix, significantly reducing their leachability, thereby aligning with environmental friendliness standards. Its adsorption capacity is about 6.60 mg/g, and the adsorption capacity per volume is 3.66 times and 2.04 times that of fly ash and clay, respectively. The mechanism analysis shows that the adsorption process is monolayer heterogeneous adsorption. This paper presents a novel perspective on reusing MSWI bottom ash and provides evidence supporting its effective utilization as a permeable subgrade material, offering substantial environmental benefits through enhanced adsorption ability. Implications: Municipal solid waste incineration (MSWI) is a common method for municipal solid waste treatment, while the MSWI bottom ash is often not reused. This paper explored the explores the feasibility of using MSWI bottom ash as a permeable road base material. The results show that the particle arrangement enables excellent shear strength and permeability, comparable to sandy soil. It meets safety requirements for the leaching of heavy metals and acts as an adsorbent for pollutants leaching from permeable pavements. Furthermore, the mechanisms underlying these behaviors of MSWI were confirmed by microstructural and mineralogical analyses. These indicate that MSWI bottom ash has great potential as a permeable road base material. This paper provides a clear understanding of the physical, mechanical and environmental properties of MSWI bottom ash, which can promote its reuse in practice.

CaO-based adsorbents derived from municipal solid waste incineration bottom ash for CO2 capture

The utilization of waste-derived adsorbents for CO2 capture presents a promising strategy for the reduction of adsorbent cost and waste volume. In this study, CaO-based adsorbent was prepared from Ca-rich municipal solid waste (MSW) incineration bottom ash (BA) as raw material. The effects of acid patterns, carbonization/calcination temperature, triblock copolymer (P123) and Mn loadings, as well as the steam contents in the flue gas on the cyclic CO2 capture capacity of the adsorbents were studied. The results showed that CaO-based adsorbents obtained by nitric- and acetic-acid extraction showed more stable adsorption capacity, due to more active CaO and less impurity content. When the Ca/Mn molar ratio was 100:1 and the concentration of P123 solution was 2 g/L, the prepared adsorbent showed the adsorption capacity of 0.321 g/g after 20 cycles, which was 175% of the unmodified CaO-based adsorbent (0.183 g/g). The addition of Mn and P123 increased the surface area and pore volume of the adsorbents, resulting in a dense distribution of pore size. Additionally, Mn could also inhibit the particle growth and mitigate sintering of the adsorbents. The electron transfer between Mn3+ and Mn4+ played a crucial role in generating labile oxygen vacancies, which improved the adsorption capacity of the adsorbents.

Preparation and characterization of polyvinyl alcohol (PVA)-glycerol composite films incorporating nanosilica from municipal solid waste incinerator bottom ash

This study investigates the fabrication of a composite film composed of polyvinyl alcohol (PVA) and glycerol, incorporating nanosilica derived from municipal solid waste incinerator bottom ash (BA). The nanosilica is blended with a PVA film-forming solution containing glycerol as a plasticizer. The composite films are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Additionally, thermogravimetric analysis (TGA) is conducted to evaluate the thermal properties, while the mechanical properties are assessed in terms of tensile strength (TS) and elongation at break (EAB). The results indicate that the presence of silica nanoparticles reduces transparency and increases film thickness in the presence of glycerol. Notably, the film containing 1% silica demonstrates a significant enhancement in tensile strength, exhibiting a 50% increase compared to the film without silica. However, higher silica loadings lead to a deterioration in mechanical properties due to silica agglomeration within the polymer matrix. As expected, the presence of silica in the films slightly elevates the degradation temperature.

Environmental and mechanical analysis of low‐carbon concrete with vitrified MSW incineration bottom ash as cement replacement

AbstractThe building sector is responsible for about 37% of the global carbon dioxide emissions, 6% of which result from concrete (and particularly cement) production. Using recycled and supplementary cementitious materials and adopting a whole building life cycle approach can be seen as multi‐beneficial strategies for materials' design. In this framework, this study aims to formulate a green concrete, by replacing 10, 15 and 20% of cement with a secondary raw material constituted of vitrified bottom ash derived from municipal solid waste incineration. The basic physical and mechanical properties were measured up to 365 days, so to evaluate the effects of the cement replacement both on short and long‐term behavior. Life Cycle Assessment was used as a tool to evaluate the environmental performance of the developed green concrete. An Eco‐Mechanical Analysis was also performed to match the environmental impacts with the mechanical behavior, allowing to assess that the concrete produced by replacing 20% of cement with vitrified municipal solid waste incineration bottom ash (if classified as hazardous waste) is the one that leads to optimize the overall sustainability. The approach proposed in this work, which can be easily generalized, contributes to the definition of a route for the implementation of innovative green construction building materials by using waste.

Utilization of municipal solid waste incinerator bottom ash (MSWIBA) in concrete as partial replacement of fine aggregate

Enhancing sustainable economic development while maintaining environmental integrity is of paramount importance. In this context, the effective utilization of municipal solid waste incinerator bottom ash (MSWIBA) presents a significant opportunity. This study investigated an approach for harnessing the potential of MSWIBA by incorporating it as a partial replacement for fine aggregate in concrete mixtures. Twelve concrete samples were prepared with varying proportions of MSWIBA. The mechanical and microstructural properties of the samples were comprehensively investigated. Moreover, the environmental and economic advantages of these concrete formulations were assessed. The results revealed that the water absorption of the concrete samples without MSWIBA was higher than that of the concrete samples with MSWIBA, suggesting that the added MSWIBA could fill the internal pores of concretes. The water absorption rate curve could be divided into three stages, i.e., rapid decline, slow decline, and stable. The optimal replacement ratio of fine aggregate with MSWIBA was between 24.8% and 57.8%. Notably, when the replacement ratio surpassed 24.8%, MSWIBA positively influenced the development of compressive strength, but it still lower than that of composite Portland cement-based concrete (OPC). Furthermore, pore structure analysis indicated that the efficacy of pore refinement was achieved within a certain replacement threshold. However, the efficacy of pore structure refinement diminished beyond that threshold. The substitution of fine aggregate with MSWIBA aligns with the technical specifications and building material standards, thereby complying with the principles of effective utilization, sustainability, and environmental consideration pertinent to MSWIBA management.