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Article

Performance and Environmental Assessment of Alkali-Activated Cements from Agricultural and Industrial Residues

by
Rafaela Pollon
1,
Giovani Jordi Bruschi
1,
Suéllen Tonatto Ferrazzo
2,
Arielle Cristina Fornari
3,
Eduarda Razador Lazzari
4,
Pedro Domingos Marques Prietto
5 and
Eduardo Pavan Korf
1,*
1
Graduate Program in Environmental Science and Technology, Federal University of Fronteira Sul, Erechim 99700-970, Brazil
2
Graduate Program in Civil Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-190, Brazil
3
Laboratory of Analytical Tests, Federal University of Fronteira Sul, Erechim 99700-970, Brazil
4
Department of Architecture and Urbanism, Federal University of Fronteira Sul, Erechim 99700-970, Brazil
5
Graduate Program in Civil and Environmental Engineering, University of Passo Fundo, Passo Fundo 99052-900, Brazil
*
Author to whom correspondence should be addressed.
Constr. Mater. 2025, 5(4), 79; https://doi.org/10.3390/constrmater5040079
Submission received: 30 August 2025 / Revised: 18 October 2025 / Accepted: 29 October 2025 / Published: 4 November 2025
(This article belongs to the Special Issue Advances in the Sustainability and Durability of Waste-Based Construction Materials)
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Abstract

The growing concern with carbon dioxide emissions from the cement industry has driven the search for alternative binders with lower environmental impact. Among these, alkali-activated cements (AACs) stand out due to their ability to produce cementitious matrices from aluminosilicate precursors and alkaline activators. However, comparisons between One-Part and Two-Part systems remain limited. This study evaluated the technical feasibility of producing AAC using sugarcane bagasse ash (SCBA) as precursor, carbide lime (CL) as calcium source, and sodium hydroxide (NaOH) as activator. Different parameters were tested, including NaOH molarities (1.0–2.5 M), SCBA/CL ratios (9.00–1.50), curing times (3, 7, and 28 days), and preparation methods. Mortars were produced at constant water/solid ratio of 1.40 and cured at room temperature (23 °C). Unconfined compressive strength (UCS) and leaching tests were performed, along with statistical analysis and Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. ACC synthesized by the Two-Part method (2.0 M NaOH, SCBA:CL 70:30) reached an UCS of 1.60 MPa at 28 days, compared to 1.39 MPa for the One-Part method. Curing time was identified as the most significant factor, followed by SCBA/CL ratio and activator molarity, while preparation method had minimal effect. The material developed alkali-activated gels, and leaching tests indicated no toxicity, although Ba concentrations exceeded regulatory limits for water quality. Potential applications include mine tailings stabilization, soil improvement, shallow foundations, and urban furniture production.

1. Introduction

The production of Portland cement has an expressive impact on global warming due to the emission of greenhouse gases, mainly carbon dioxide (CO2). It is estimated that cement manufacturing accounts for approximately 7–10% of global CO2 emissions [1]. In terms of energy demand, the average consumption in Brazil reaches 103 kWh per ton of cement produced [2]. Furthermore, Portland cement relies on the extraction of non-renewable raw materials, primarily limestone and clay, requiring approximately 1.6 tons of raw feedstock to produce 1 ton of cement [3].
In this context, alkali-activated cements (AACs) have emerged as a promising alternative with lower environmental impact [4,5]. AACs are produced through the reaction between an amorphous aluminosilicate precursor and an alkaline activator, forming hydrated gels such as N(K)-A-S-H (sodium/potassium aluminosilicate hydrate), C-A-S-H (calcium aluminosilicate hydrate), or hybrid gels C(N,K)-A-S-H [6]. AAC systems can be classified according to calcium content (high, low, or intermediate) [7,8], and by preparation method: Two-Part systems, in which precursors are combined with alkaline solutions, and One-Part systems, where precursor and activator are blended in solid state, requiring only the addition of water, similar to Portland cement [9].
The Two-Part method typically uses highly alkaline hydroxide or silicate solutions as the first component, and solid aluminosilicates as the second. Handling these concentrated, viscous, and corrosive solutions imposes logistical challenges in terms of transportation, storage, and application [10]. Conversely, the One-Part method, often referred to as “just add water”, eliminates the use of corrosive liquid activators, simplifying the process and making it more comparable to Portland cement, thereby increasing commercial attractiveness and practical feasibility [11].
Comparative studies have highlighted differences between these systems. Yin et al. [12] demonstrated that One-Part AAC generally develop lower compressive strength and less dense microstructures, while showing comparable flexural strength, similar mass loss under drying, and significantly reduced shrinkage and cracking compared to Two-Part systems.
AAC precursors may include natural raw materials or industrial residues containing SiO2 and Al2O3. Examples include metakaolin [13], ceramic waste [14], fly ash [15], waste glass [16], blast furnace slag [17], iron ore tailings [18,19], gold tailings [20], sugarcane bagasse ash (SCBA) [21], corncob ash [22], rice husk ash [23,24,25], bricks waste, filter dusts [26], municipal solid waste incineration fly ash [20,27], steel slag [27], etc. Calcium can be naturally present in some residues, such as slag, or externally added through commercial lime or alternative sources such as hydrated eggshell lime [28], oyster shell lime [29], or carbide lime (CL), a by-product of acetylene production, consisting primarily of calcium hydroxide [6,30].
SCBA is a particularly relevant precursor in Brazil, the world’s largest sugarcane producer, with an estimated 676.96 million tons in the 2024/2025 harvest [31]. Bagasse represents about 30% of sugarcane mass, and its combustion for energy generation produces approximately 25 kg of SCBA per ton of bagasse [32]. This residue is often disposed of improperly, either in open dumps [33] or with limited applications in agriculture and construction, where further studies are required to assess its environmental performance and leaching behavior [34].
Several studies have investigated the use of SCBA in alkali-activated systems. Sousa et al. [35] evaluated the production of AAC using SCBA as a precursor, characterizing the pastes in terms of compressive strength, mineralogical composition, and microstructural properties. The material demonstrated satisfactory performance, highlighting residue-based alkali-activated cements as a promising and sustainable alternative for civil construction. Another study [36] investigated AAC formulations incorporating SCBA and ground blast furnace slag as precursors, focusing on their mechanical behavior. The findings confirmed the material’s potential as an environmentally friendly binder with favorable engineering properties. Tonini de Araújo et al. [37] reported satisfactory mechanical performance of an AAC produced from SCBA and hydrated eggshell lime, with the formation of C–A–S–H and N–A–S–H gels. Lima et al. [38] aimed to develop AAC utilizing blast furnace slag and SCBA, demonstrating that the incorporation of SCBA reduced energy consumption while maintaining satisfactory performance, confirming the technical feasibility of this waste utilization. Iqbal et al. [39] investigated AAC systems incorporating SCBA and polyvinyl alcohol fibers, reporting improvements in both mechanical and durability properties, which highlight the potential of SCBA-based AAC as a viable alternative material for construction applications.
Carbide lime represents another residue with potential for AAC production. An estimated 1.4 million tons are discarded annually worldwide, with 17,000 tons per year in Brazil alone [40,41,42]. Owing to its high Ca(OH)2 content (equivalent to ~71% CaO) [43,44,45], CL disposal in landfills poses environmental risks and high treatment costs. Its reuse in AAC could reduce the extraction and calcination of limestone, stages responsible for the highest environmental impacts in the life cycle of commercial lime production [28,46]. Carbide lime has been employed in several studies, often combined with other industrial residues such as waste glass, for the development of AAC. These materials exhibited satisfactory performance, demonstrating their potential as alternative binders for geotechnical and soil stabilization purposes [16]. Lotero et al. [14] investigated an AAC produced from red ceramic waste (precursor) and carbide lime (calcium source), confirming the formation of C-A-S-H and (N,C)-A-S-H gels and demonstrating the technical feasibility of this cement for on-site applications without thermal curing. Similarly, Consoli et al. [47] studied an AAC derived from construction and demolition ceramic powder and carbide lime, reporting the development of a heterogeneous cementitious matrix with an amorphous aluminosilicate gel.
Considering these factors, the combination of SCBA and CL represents a potential alternative to Portland cement. Although previous studies have investigated their mechanical behavior [30,48,49], research addressing microstructure, reaction products, and leaching remains limited. Furthermore, comparative evaluations of SCBA–CL AAC produced by One-Part and Two-Part methods are still scarce. This study aims to advance this knowledge gap by developing AAC based on SCBA and CL, assessing the influence of NaOH molarities (1.0–2.5 M), SCBA/CL ratios (9.00–1.50) and curing times (3, 7 and 28 days), on compressive strength, and comparing the performance of One-Part and Two-Part systems. Additional characterization includes chemical composition, mineralogy, microstructure, and leaching behavior of the developed binders. The outcomes of this study address the effects of the One-Part and Two-Part methods on ACC performance, optimal mix design, and the leaching or encapsulation of metals from waste used in the cemented matrix.

2. Materials and Methods

2.1. Materials

The materials used in this study were sugarcane bagasse ash (SCBA) as precursor, carbide lime (CL) as supplementary calcium source, sodium hydroxide (NaOH) as alkaline activator, and distilled water. The SCBA was supplied by a company located in the northwest region of Porto Xavier, Rio Grande do Sul, Brazil, and was generated from combustion of sugarcane bagasse at temperatures between 500 and 700 °C. The CL was obtained from an acetylene gas production plant in Sapucaia do Sul, Rio Grande do Sul, Brazil. The NaOH was used in micropearls with a purity of 97%.

Materials Characterization

The SCBA was oven-dried at 105 °C for 24 h and sieved through a 200-mesh sieve (75 µm aperture). The CL was dried at 60 °C for 72 h and also sieved through a 200-mesh sieve (75 µm aperture). The main properties of the materials are presented in Table 1, while the particle size distribution is shown in Figure 1, exhibiting results comparable to those reported in previous studies [40,50].
The X-ray diffraction (XRD) analysis of SCBA was performed by Tonini de Araújo et al. [37] using a Bruker D2 Phaser, second generation (Bruker, Billerica, MA, USA) with Cu-Kα radiation, under operating conditions of 20 kV and 10 mA. Data were collected over a 2θ range of 10–70°, with a step size of 0.02°, step time of 1 s, and phase identification carried out using the Crystallography Open Database. The mineralogical composition revealed the presence of quartz (SiO2), magnetite (Fe3O4), and hematite (Fe2O3), as illustrated in Figure 2.
The mineralogy of CL, also shown in Figure 2, was obtained through XRD analysis by Bruschi et al. [48] using a Rigaku Miniflex II diffractometer (Rigaku, Toyo, Japan), equipped with a nickel filter and Cu-Kα radiation (λ = 1.5406 Å). The scan was performed at a rate of 0.05° (2θ) per minute. The identified crystalline phases included portlandite [Ca(OH)2] and calcite (CaCO3).
The chemical composition of SCBA, determined by Tonini de Araújo et al. [37], is presented in Table 2 and shows a predominance of silicon oxide (SiO2) and iron oxide (Fe2O3). For comparison, the chemical composition of CL, reported by Bruschi et al. [48], is also included in Table 2, with calcium oxide (CaO) as the main constituent.
Leaching and solubilization tests of CL were carried out in accordance with Brazilian standards NBR 10005 [52] and NBR 10006 [53]. For the leaching test (NBR 10005 [52]), 100 g of dried sample, previously sieved through a 9.5 mm mesh, was mixed with a glacial acetic acid solution (HOAc, pH = 2.88 ± 0.05) at a solid-to-liquid ratio of 1:20. The suspension was agitated in a rotary shaker at 30 rpm for 18 ± 2 h at 25 °C. After agitation, the leachate was filtered, and the concentrations of metals were determined by inductively coupled plasma optical emission spectrometry (ICP-OES, Shimadzu brand, model ICPE-9820, from Tokyo, Japan), with a multielement standard solution (ICP Certipur, Merck brand). A Hanna pH meter model HI 2221 was used to determine the pH. Then, the values were compared against the threshold values established in Annex F of NBR 10004 [54].
For the solubilization test (NBR 10006 [53]), 250 g of dried sample was mixed with 1000 mL of deionized water, in duplicate. The suspensions were agitated for 5 min and then left to stand for 7 days at 25 °C. After the resting period, the solubilized extracts were filtered, and metal concentrations were analyzed by ICP-OES, with results compared to the limits defined in Annex G of NBR 10004 [54].
The leachate from CL showed metal concentrations below the maximum limits of Annex F of NBR 10004 [54]. Similarly, the solubilized extract presented concentrations lower than those of Annex G, classifying CL as a non-hazardous, inert residue (Class II B).

2.2. Experimental Program

According to Pollon et al. [21], a systematic review demonstrated that the presence or absence of calcium and the type of alkaline activator are the key factors influencing the development of AAC based on SCBA. With respect to curing, the literature shows a preference for room temperature (23 °C), due to lower energy demand and ease of application, as well as for shorter curing times, typically 7 and 28 days.
Sodium hydroxide (NaOH) is one of the most widely used alkaline activators in the production of alkali-activated cement [21]. In this study, it was employed at low concentrations (up to 2.5 M) due to the environmental and economic impacts associated with this chemical compound [55,56], as well as the use of a calcium source in the alkali-activated system (e.g., carbide lime), which enables the attainment of pH values above 12.4 and allows the use of alkaline activators at lower concentrations and under ambient temperature [16,57]. The water-to-solid ratio was fixed at 1.40, based on preliminary tests that established the minimum amount of water required to homogenize the drier mixtures in both mixing methods.
The SCBA/CL ratios were defined following the study by Tonini de Araújo et al. [37]. The comparison between One-Part and Two-Part systems was chosen to assess the performance of binders produced by each method, identifying similarities and differences in mechanical behavior. Thus, the fixed variables were: type of activator (sodium hydroxide), curing temperature (23 °C), and water-to-solid ratio (1.40). The controlled variables and their respective levels are presented in Table 3.
A full factorial design was adopted, with four controlled variables and duplicate runs, resulting in a total of 192 experimental combinations. The response variable investigated was the unconfined compressive strength (UCS), used to evaluate the mechanical performance of the binders.

2.3. Molding and Curing Procedures

For the One-Part method, SCBA powder, CL powder, and sodium hydroxide micropearls were initially homogenized in the dry state, and distilled water was added afterwards, followed by additional mixing to ensure uniformity. For the Two-Part method, SCBA powder and CL powder were first homogenized, and the NaOH was introduced by solution (water + NaOH), previously cooled to room temperature, then it was mixed again. There were no additives or procedural variations involved.
Specimens for both mixing methods were cast in PVC cylindrical molds with a diameter of 3.7 cm and a height of 7.4 cm. The mixtures were placed in a single layer without compaction; to eliminate voids and entrapped air bubbles, vibration was applied. After casting, the saturated specimens were kept at a controlled temperature of 23 ± 2 °C under ambient humidity conditions until testing.

2.4. Unconfined Compressive Strength (UCS)

The uniaxial compressive strength (UCS) tests were performed in accordance with ASTM C39/C39M [58]. The compressive load was applied at a constant displacement rate of 1.14 mm/min using an automatic testing machine with a maximum capacity of 100 t (brand: Engetotus, Contagem, Brazil).

2.5. Statistical Analysis

To evaluate the influence of the studied factors and their interactions on the response variable (UCS), an analysis of variance (ANOVA) was performed using Minitab software version 19, with a response surface model adjusted and confidence level of 95% (p-value < 0.05). In addition, Tukey’s post hoc test was applied to determine whether the variable levels were statistically equal or significantly different.

2.6. Chemical, Microstructural, and Leaching Analysis

Based on the unconfined compressive strength (UCS) results, the formulations with the highest average values at each curing time (3, 7, and 28 days) were selected, since preliminary analyses indicated that curing time had the greatest influence on strength development. In addition, to enable comparison between the mixing methods (One-Part and Two-Part), the formulations with the highest average UCS values for each method were also selected. This selection resulted in six distinct compositions, which were subsequently subjected to microstructural analyses (SEM, XRD, and FTIR) and metal leaching tests. The selected formulations are presented in Table 4.
The selected samples were ground to pass through a 9.5 mm sieve for leaching tests, which were performed immediately after curing, in accordance with NBR 10005 [52], as described in Section Materials Characterization
For the remaining analyses, samples were subjected to interruption of chemical reactions by immersion in acetone for 48 h, followed by oven drying at 40 °C for 24 h [59], and subsequently stored in sealed plastic bags. These specimens were later used for FTIR, XRD, and SEM analyses to evaluate cementitious gel formation and microstructural characteristics.
Fourier-transform infrared spectroscopy (FTIR) analyses were conducted using a Perkin Elmer Spectrum 1000 spectrometer (Perkin Elmer, Shelton, CT, USA) in the range of 4000–400 cm−1 with a resolution of 4 cm−1. X-ray diffraction (XRD) analyses were performed on a Siemens–Bruker AXS D-5000 (θ–2θ) diffractometer (Bruker, Billerica, MA, USA), equipped with a Cu anode tube (λ = 1.5406 Å), operating at 40 kV and 25 mA. Measurements were carried out using the powder method, within a 2θ range of 2–72°, with a step size of 0.05° and a counting time of 1 s per step.
Scanning electron microscopy (SEM) analyses were carried out using a TESCAN VEGA 4 LMU microscope equipped with an EDS detector (TESCAN, Brno, Czech Republic). Prior to analysis, the samples were sputter-coated with gold at 10 mA for 240 s to render the surface conductive. Imaging was performed at 20 kV with a beam current of 300 pA, while EDS spectra were acquired at 20 nA.

3. Results

3.1. Mechanical Behavior

Figure 3 shows the UCS as a function of curing time for (a) 1.0 M, (b) 1.5 M, (c) 2.0 M, and (d) 2.5 M NaOH concentrations, comparing the One-Part and Two-Part mixing methods. In general, UCS values increased with curing time, indicating that the binder reactions continued throughout the entire curing period [48].
With respect to activator molarity, 1.5 M and 2.0 M yielded higher average strengths compared to the extreme values of 1.0 M and 2.5 M. Overall, an increase in strength was observed with increasing molarity; however, at SCBA/CL ratios close to 1.50, the average UCS values decreased. This reduction can be attributed to the limited solubility at higher molarities, which requires a greater amount of CL to sustain adequate strength development [48].
Intermediate SCBA/CL ratios of 2.33 and 4.00 yielded higher average UCS values compared to the extreme ratios of 1.50 and 9.00. The SCBA/CL ratio plays a critical role in strength development of alkali-activated materials, as Ca2+ cations react with silicates in SCBA to form calcium silicate hydrate (C-S-H) phases [60]. However, both very low and very high calcium contents can impair mechanical strength. Insufficient calcium delays the formation of cementitious products, whereas excessive calcium may lead to Ca2+ saturation and subsequent carbonation [48,60].
The comparison of mixing methods revealed similar results overall, with the Two-Part method showing slightly higher UCS values. This can be explained by the fact that in the Two-Part system, the alkaline activator is fully dissolved prior to mixing, which facilitates reaction with the precursor. In contrast, in the One-Part system, when water is added at the final stage, part of it is absorbed onto the surface of dry precursors and distributed within particle voids, reducing the extent of reaction despite the localized temperature increase [61]. At 2.0 M NaOH, the highest strength recorded in this study was 1.60 MPa at 28 days with an SCBA/CL ratio of 2.33 using the Two-Part method, while the One-Part system under the same conditions reached 1.39 MPa.
Some possible ways to increase these UCS values would be to evaluate higher curing temperature and longer curing times and to work with a SCBA originating from a controlled burn, which has more amorphous content, greater reactivity and consequently greater formation of cementing gels.
The AAC investigated exhibited a significant increase in UCS values after 7 days of curing. Figure 4 presents the ANOVA results, showing the significance of the controlled variables (A, B, C, and D) and their interactions on UCS. The significant variables (p-value > 0.05, corresponding to Standardized Effect = 2) were, in order of magnitude of the F-value: curing time (F-value = 312.64), SCBA/CL ratio (F-value = 46.31), and activator molarity (F-value = 5.11).
This behavior is consistent with the results shown in Figure 3, as curing time was the variable with the strongest influence on UCS. This can be explained by the fact that the hydration and geopolymerization reactions continue to progress over time, provided that reactive constituents remain available in the system. Second-order interactions between the variables were also significant, particularly AB, BC, and AC. In contrast, the mixing method (p > 0.05; F = 0.50) and its interactions were not statistically significant, confirming the trends shown in Figure 3, since UCS values for both One-Part and Two-Part methods were very similar.
Table 5, Table 6 and Table 7 present the comparison of mean values for the variables considered in isolation, without interactions, based on Tukey’s test at a 95% confidence level. It can be observed that all curing times produced statistically different UCS responses (Table 5). Strength values consistently increased with curing time, indicating that calcium from CL and silica from SCBA were still reacting, although not fully consumed [41].
Table 6 shows that SCBA/CL ratios of 4.00 and 2.33 produced statistically similar UCS values, while the extreme ratios of 1.50 and 9.00 yielded significantly lower strengths. Thus, intermediate levels of CL (ratios of 4.00 and 2.33) resulted in higher UCS, whereas extreme values led to strength reduction. Similar findings were reported by Pompermaier et al. [62]. This behavior occurs because calcium content plays a critical role in the strength development of alkali-activated materials: Ca2+ cations react with silicates in SCBA to form calcium silicate hydrate (C-S-H). However, insufficient calcium limits the formation of cementitious products and compromises strength [48,60], while excessive calcium leads to saturation and carbonation, also impairing mechanical performance [60,63].
Among the ratios with statistically similar UCS results, the ratio of 4.00 is recommended, since it incorporates a higher proportion of SCBA. This is advantageous as SCBA is produced in large quantities [31,32] and contains a wider variety of oxides, which increases disposal challenges.
Table 7 presents the effect of activator molarity, showing that 1.5 M and 2.0 M yielded statistically similar UCS values, both corresponding to the highest strengths. This suggests the existence of a saturation point in the alkaline activation reaction, where a minimum concentration of Na+ is sufficient to maximize the formation of cementitious gels [64]. Therefore, 1.5 M is preferable, as it requires less activator, reducing costs and environmental impacts.
Figure 5 illustrates the main effects of the studied variables on UCS. With increasing curing time, UCS rises continuously due to ongoing reactions. The SCBA/CL ratio shows a linear increase in UCS up to 4.00, followed by a decrease. Regarding NaOH molarity, UCS increased from 1.0 M to 1.5 M, then decreased at higher concentrations. These trends are consistent with Tukey’s comparisons: a minimum concentration of NaOH is necessary to dissolve silica and alumina, but excessive alkalinity reduces compressive strength. Higher alkali concentrations hinder the dissolution of calcium oxide from CL, thereby limiting the formation of C-A-S-H gels and ultimately decreasing UCS [65,66].
Although the UCS values obtained with the Two-Part method were slightly higher than those of the One-Part method, the results from both approaches were statistically equivalent within the variables and levels evaluated in this study. The effects of the investigated factors on UCS confirmed the trends already observed in Figure 3.
Figure 6 presents the contour surface plot for the two most significant variables, curing time and SCBA/CL ratio. The plot shows that higher curing times combined with lower SCBA/CL ratios resulted in the highest UCS values. Accordingly, for the AAC studied, the optimal conditions identified from the statistical analysis were: curing time of 28 days, SCBA/CL ratio of 80/20 (4.00), NaOH concentration of 1.5 M, and One-Part mixing method. Under these conditions, the UCS reached 1.23 MPa, which is close to the maximum value obtained in this study (1.60 MPa).

3.2. Microstructure

SEM/EDS images of the samples with the best results at 3, 7, and 28 days of curing for the Two-Part method are shown in Figure 7, Figure 8 and Figure 9. As observed in Figure 7a, Figure 8a and Figure 9a, all specimens exhibited a heterogeneous microstructure with intrinsic porosity. The particles displayed varied geometrical morphologies, attributed to the presence of silicon oxides (SiO2) and iron oxides (Fe2O3), as well as the possible formation of hybrid gels C(Na,K)-A-S-H, primarily in the form of calcium silicate hydrates (C-S-H) and sodium-calcium aluminosilicate hydrates (C(Na)-A-S-H).
At 1000× magnification, little difference was visually observed between the samples cured for 3 and 7 days, which is consistent with the UCS results: a significant increase in strength was only achieved after 7 days of curing (see Figure 5). The specimen cured for 28 days, in contrast, exhibited a denser microstructure and the formation of larger particles.
Elemental mapping by EDS revealed a homogeneous distribution of Al, Ca, Mg, Na, K, P, and O across the surface, while Si, Fe, and Ti showed less uniform distributions and localized clusters, as illustrated in Figure 7c, Figure 8c and Figure 9c. The detection of Al, P, Mg, K, and Ti oxides in minor amounts is consistent with the composition of the raw materials.
Surface composition determined by EDS spectra (Figure 7d, Figure 8d and Figure 9d) showed that the 3-day and 7-day cured samples, both prepared with 1.5 M NaOH and SCBA/CL ratio of 4.00, presented similar concentrations of Na, Si, and Ca. The 28-day cured sample, produced with a higher activator concentration (2.0 M NaOH) and lower SCBA/CL ratio (2.33), exhibited an increase in Na and a decrease in Si content, in agreement with the precursor proportions. For all samples, the elemental ratios ranged within 0.75 < Ca/Si < 1.08 and 0.28 < Na/Si < 0.44.
The EDS spectra of the samples confirmed the formation of cementitious gels in all materials. The presence of Si, together with higher O contents in some regions, reiterates the availability of dissolved silica (SiO2) within the pores.
Higher-magnification SEM images (Figure 7e, Figure 8e and Figure 9e) revealed that longer curing times led to smoother surfaces, suggesting pore closure and increased compaction, which explains the improved mechanical performance. Similar results were reported by Corrêa-Silva et al. [67]. In addition, EDS analyses identified the formation of gel structures on silica particles, which became denser and less fibrous with curing progression, particularly between 7 and 28 days (Figure 8e and Figure 9e).
XRD analyses (Figure 10) indicated a very similar mineralogy among all selected samples, with the presence of semicrystalline and crystalline phases. All samples contained quartz (SiO2) and cristobalite (SiO2), originating from SCBA, as well as calcite (CaCO3) from CL. Only the 3-day Two-Part sample showed portlandite [Ca(OH)2], derived from CL, which had not yet been fully consumed in the formation of cementitious products at early curing stages.
The formation of N-A-S-H gel fills the voids within the mixtures, contributing to improved UCS results. The presence of this gel is suggested by the amorphous phases observed in the 2θ range of 20–35° [8]. Although the high intensity of quartz peaks makes it more difficult to clearly identify amorphous phases in the mineralogy of the samples [68], the diffraction band between 28° and 32° indicates the possible formation of cementitious gels (C-S-H and C-A-S-H), generated by reactions with calcite. This suggests that hydration processes are ongoing, corroborating the results obtained from SEM/EDS analyses [69]. FTIR analysis was conducted to complement and support the XRD results.
The FTIR spectra (Figure 11) allowed the identification of cementitious products and chemical compounds present in the mixtures. The absorption bands near 3500 cm−1 and 3400 cm−1, observed in all samples, correspond to hydrated products associated with O–H bonds and hydroxyl groups from adsorbed water, respectively [37,70,71].
The absorption bands near 2900 cm−1 and 2800 cm−1 correspond to methylene (CH2) groups, associated with symmetric and asymmetric stretching vibrations [72]. In all samples, an absorption band between 1645 and 1627 cm−1 was observed, attributed to H–O–H bending vibrations [73]. Only the 28-day cured Two-Part sample exhibited a band around 1500 cm−1, related to O–C–O bonds, suggesting possible carbonation [74].
All samples showed absorption bands in the range of 1450–1417 cm−1 or near 870 cm−1, corresponding to C–O bonds and the presence of CO32− groups. These are typical of unsealed or untreated alkali-activated binders, arising from carbonate formation through the reaction of NaOH with atmospheric CO2 [8,75,76,77,78].
The bands between 1025 and 1016 cm−1, identified in all 3-day and 7-day cured samples, are associated with asymmetric stretching vibrations (T–O–T, with T = Si or Al) characteristic of N-A-S-H gel [8,77]. As curing progresses (3, 7, and 28 days), the peaks shift and change shape as gel polymerization increases, as seen in Figure 11, the peak near 1000 cm−1 (red circles) is observed moving to slightly lower frequencies (green circles), indicating greater Si–O–T condensation. Studies confirm that an initial peak at ~998 cm−1 disappears and gives way to a band at ~960–943 cm−1 in the final product, reflecting greater order and polymerization of the structure [79].
In the Two Part mix (activator already in solution), the alkaline reagent is immediately available, while in the One Part mix (mixed solid activator), there is greater heat release and simultaneous dissolution of all phases, accelerating the reaction mechanisms. It can be inferred that One Part systems exhibit similar or even faster spectral changes than Two Part systems, but both eventually converge around 28 days, when gel polymerization is greater.
Peaks near 970 cm−1 and between 800 and 700 cm−1 are attributed to asymmetric Si–O–T stretching vibrations (T = Si or Al tetrahedra), serving as distinctive markers of gels formed after alkali activation [8,80,81]. These bands may correspond to both C-S-H and C-A-S-H gels [82,83].
The absorption bands between 700 and 600 cm−1 are mainly related to Si–O–Si bending vibrations, attributed to C-S-H gels [76], while the lower-frequency bands around 450 cm−1 are associated with O–Si–O vibrations [84]. Thus, all samples exhibited characteristic FTIR bands corresponding to alkali-activated gels (C-S-H, C-A-S-H, and N-A-S-H).
However, the FTIR results do not directly reflect the UCS trends (which increased with curing time), likely because the alkali-activation reactions are of low intensity, and their spectroscopic features are not linearly correlated with mechanical strength development.

3.3. Leaching Behavior

Table 8 presents the concentrations of metals in the leachates of the mixtures that achieved the highest UCS values at each curing age and for each mixing method (One-Part and Two-Part). For all alkali-activated matrices, the concentrations of leached metals were below the threshold limits established in Annex F of NBR 10004 [54]. Therefore, the alkali-activated materials tested in this study can be classified as non-toxic with respect to metal leaching.
In the case of barium (Ba), it was detected in the leachates of both SCBA and CL residues, as well as in all cementitious samples, at concentrations exceeding the most restrictive thresholds, namely those for water quality standards [85,86]. The leaching of Ba from both residues and alkali-activated mixtures can be explained by its amphoteric nature, which increases its mobility and solubility under highly alkaline conditions, such as those found in AAC systems [51,87]. Unlike sodium, Ba does not readily integrate into the cementitious gel structure, making it more susceptible to leaching [88]. Furthermore, barium oxide can react with dissolved carbon dioxide (CO2) in water, forming barium carbonate (BaCO3), which is soluble in the acetic acid solution used in the leaching tests [89].
Table 8. Chemical composition of leachate extracts from raw materials and mixtures (mg·L−1).
Table 8. Chemical composition of leachate extracts from raw materials and mixtures (mg·L−1).
MetalSCBACL3 Days7 Days28 DaysNBR 10004 Annex FCONA-
MA 420 1		Dutch List 2EPA 3
1.5 M1.5 M2.0 M
Ash/Lime Ratio 4.00Ash/Lime Ratio 4.00Ash/Lime Ratio 2.33
One PartTwo PartOne PartTwo PartOne PartTwo Part
Ag********50.05--
Al********-3.5--
As********10.010.010.01
Ba0.08 **0.180.410.430.420.400.280.36700.070.052
Cd********0.50.0050.00040.005
Cr********50.050.0010.1
Cu********-20.0151.3
Fe**0.010.0120.0240.0200.0330.022-2.45--
Hg********0.10.0010.000050.002
Mn********-0.4--
Pb0.06*******10.010.0150.015
Se********10.01-0.05
Zn********-1.050.065-
* = Below detection limit; ** Values highlighted in bold show concentrations that exceed at least one legal limit; 1 = Brazilian Norm CONAMA 420 [86]; 2 = Groundwater target values (Netherlands) [85]; 3 = National Primary Drinking Water Regulations (USA) [90].
According to NBR 10005 [52], samples were fragmented into particles smaller than 9.5 mm, increasing the surface area and thereby enhancing the dissolution of certain metals [91]. In this case, for future studies, it would be interesting to investigate some mitigation strategies for Ba, as an additive for encapsulation or pH control to reduce its leaching.
On the other hand, the alkali-activated mixtures did not exhibit leaching of lead (Pb), which was present in the leachate of SCBA (Table 8). This indicates that the cementitious matrix was able to immobilize Pb from the residue. This immobilization may have occurred through Pb precipitation followed by encapsulation within cementitious gel phases. In alkali-activated materials, heavy metals such as Pb can be immobilized by charge-balancing incorporation into the gel structure [92,93]. In addition, iron (Fe), originating from SCBA, did not exceed any regulatory limits in the mixtures. These results can be attributed to the use of acetic acid as the extraction solution, which creates a more acidic medium and promotes the dissolution of metals with a cationic behavior [94].

4. Conclusions

This study investigated alkali-activated cements (AACs) produced with sugarcane bagasse ash (SCBA) and carbide lime (CL), activated with sodium hydroxide through One-Part and Two-Part methods. The results demonstrated that:
  • Curing time, SCBA/CL ratio, and activator molarity were the key factors influencing mechanical performance, with curing time being the most significant variable.
  • The maximum uniaxial compressive strength (1.60 MPa) was achieved with 2.0 M NaOH, 28 days of curing, an SCBA/CL ratio of 2.33, and the Two-Part method. However, from a practical perspective, the optimal balance between cost, environmental impact, residue utilization, and strength development was obtained with 28 days of curing, an SCBA/CL ratio of 4.00, 1.5 M NaOH, and the One-Part method. The observed limitation in maximum strength indicates that the alkaline reaction did not reach an adequate level of polymerization and structural cross-linking necessary for forming a cohesive gel network. Such a network would typically enhance UCS values, resulting in greater mechanical cohesion. This theory aligns with a scenario where a notable amount of precursors are left unreacted or where the resulting product is characterized by inadequate cross-linking, leading to a poorly structured and porous gel.
  • Microstructural and mineralogical analyses confirmed the presence of cementitious gels, including C-S-H, N-A-S-H, and C-A-S-H, supporting the mechanical behavior observed.
  • SEM/EDS revealed heterogeneous but increasingly compact microstructures with curing, while XRD and FTIR indicated ongoing hydration and the formation of reaction products typical of alkali activation.
  • Leaching tests showed no evidence of toxicity, with Ba being the only element above water quality limits, a behavior attributed to its amphoteric nature and higher solubility under alkaline conditions.
  • Future studies should investigate strategies to increase strength, as wet-dry cycles, long-term durability, Ba immobilization techniques, life cycle assessment, alkali-aggregate reaction and an economic evaluation to expand the applicability of SCBA–CL AAC.
  • Overall, the AAC developed in this research presents technical feasibility for applications compatible with its strength levels. Potential uses include soil stabilization, mine tailings stabilization, shallow foundations in small-scale construction, and the production of non-structural urban furniture elements such as benches, tables, and other public infrastructure components. The potential applications of such binders remain preliminary, and future studies should evaluate them more deeply.

Author Contributions

Conceptualization, E.P.K. and P.D.M.P.; methodology, R.P. and E.R.L. software, R.P., A.C.F. and E.P.K.; validation, E.P.K., G.J.B. and S.T.F.; formal analysis, R.P. and E.P.K.; investigation, R.P., E.R.L. and A.C.F.; resources, E.P.K.; data curation, R.P. and E.P.K.; writing—original draft preparation, R.P. and A.C.F.; writing—review and editing, G.J.B., S.T.F., P.D.M.P. and E.P.K.; visualization, R.P. and A.C.F.; supervision, E.P.K.; project administration, E.P.K.; funding acquisition, E.P.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by [Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil—CAPES], by [Conselho Nacional de Desenvolvimento Científico Tecnológico—CNPq]—Research Productivity Fellowship [305910/2023-0] and scientific initiation fellowship, and by [Financiadora de Estudos e Projetos—FINEP].

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
AACAlkali-Activated Cements
CLCarbide Lime
FTIRFourier Transform Infrared Spectroscopy
SCBASugarcane Bagasse Ash
SEMScanning Electron Microscopy
UCSUniaxial Compressive Strength
XRDX-ray Diffraction
N(K)-A-S-HSodium/Potassium Aluminosilicate Hydrate
C-A-S-HCalcium Aluminosilicate Hydrate
C(N,K)-A-S-HCalcium-Sodium/Potassium Aluminosilicate Hydrate
ICP-OESInductively Coupled Plasma Optical Emission Spectrometry
ANOVAAnalysis of Variance
PVCPolyvinyl Chloride

References

  1. Moradikhou, A.B.; Esparham, A.; Avanaki, M.J. Physical & Mechanical Properties of Fiber Reinforced Metakaolin-Based Geopolymer Concrete. Constr. Build. Mater. 2020, 251, 118965. [Google Scholar] [CrossRef]
  2. BRASIL. Modelagem Setorial de Opções de Baixo Carbono para o Setor de Cimento; Ministério da Ciência, Tecnologia, Inovações e Comunicações: Brasília, Brazil, 2017; ISBN 978-85-88063-48-8. [Google Scholar]
  3. Dai, T.; Fang, C.; Liu, T.; Zheng, S.; Lei, G.; Jiang, G. Waste Glass Powder as a High Temperature Stabilizer in Blended Oil Well Cement Pastes: Hydration, Microstructure and Mechanical Properties. Constr. Build. Mater. 2024, 439, 137359. [Google Scholar] [CrossRef]
  4. Wu, X.; Xiong, Z.; Zhu, W.; Shan, X.; Yang, E.-H. Developing Sustainable Cement through Alkali-Activation of Waste Glass and Hydrophobic Modification. Constr. Build. Mater. 2025, 479, 141507. [Google Scholar] [CrossRef]
  5. Liang, G.; She, A.; Yao, W. Sustainable Use of Recycled Sand in Alkali-Activated Cement and Portland Cement Mortars: A Comparative Study with Natural Sand. Sustain. Mater. Technol. 2025, 43, e01290. [Google Scholar] [CrossRef]
  6. Bernabeu, J.P.; Monzó, J.; Borrachero, M.V.; Soriano, L.; Tashima, M.M. Ativadores Alternativos Para Cimentos Ativados Por Alcalinos. Rev. ALCONPAT 2022, 12, 16–31. [Google Scholar] [CrossRef]
  7. Provis, J.L.; Van Deventer, J.S.J. (Eds.) Alkali Activated Materials: State-of-the-Art Report, RILEM TC 224-AAM; Springer: Dordrecht, The Netherlands, 2014; Volume 13, ISBN 978-94-007-7671-5. [Google Scholar]
  8. Garcia-Lodeiro, I.; Palomo, A.; Fernández-Jiménez, A.; Macphee, D.E. Compatibility Studies between N-A-S-H and C-A-S-H Gels. Study in the Ternary Diagram Na2O–CaO–Al2O3–SiO2–H2O. Cem. Concr. Res. 2011, 41, 923–931. [Google Scholar] [CrossRef]
  9. Cristelo, N.; Garcia-Lodeiro, I.; Rivera, J.F.; Miranda, T.; Palomo, Á.; Coelho, J.; Fernández-Jiménez, A. One-Part Hybrid Cements from Fly Ash and Electric Arc Furnace Slag Activated by Sodium Sulphate or Sodium Chloride. J. Build. Eng. 2021, 44, 103298. [Google Scholar] [CrossRef]
  10. Qin, Y.; Qu, C.; Ma, C.; Zhou, L. One-Part Alkali-Activated Materials: State of the Art and Perspectives. Polymers 2022, 14, 5046. [Google Scholar] [CrossRef] [PubMed]
  11. Provis, J.L. Alkali-Activated Materials. Cem. Concr. Res. 2018, 114, 40–48. [Google Scholar] [CrossRef]
  12. Yin, K.; Jiang, Y.; Pan, Y.; Li, Z.; Xie, N.; Meng, J. Properties Comparison of One-Part and Two-Part Alkali-Activated Slag Pastes. Case Stud. Constr. Mater. 2024, 21, e03884. [Google Scholar] [CrossRef]
  13. Yuan, C.; Hu, H.; Bai, W.; Guan, J.; Lv, Y.; Xie, C.; Li, L. Multiscale Strength Formation Mechanism and Stress-Strain Behavior of Alkali-Activated Metakaolin Concrete Considering the Effect of Alkaline Solution/Binder Ratio. J. Mater. Res. Technol. 2025, 37, 4830–4844. [Google Scholar] [CrossRef]
  14. Lotero, A.; Moncaleano, C.J.; Consoli, N.C. Alkali-Activated Red Ceramic Wastes-Carbide Lime Blend: An Alternative Alkaline Cement Manufactured at Room Temperature. J. Build. Eng. 2023, 65, 105663. [Google Scholar] [CrossRef]
  15. Costa, H.N.; Argonz, R.; Cabaral, A.E.B.; Nogueira, R.E.F.Q. Comportamento No Estado Fresco e No Estado Endurecido de Pastas de Cimentos Álcali-Ativados de Cinza Volante e de Cinza Pesada e Suas Características Microestruturais. Ambiente Construído 2023, 23, 203–223. [Google Scholar] [CrossRef]
  16. Lotero, A.; Consoli, N.C.; Moncaleano, C.J.; Neto, A.T.; Koester, E. Mechanical Properties of Alkali-Activated Ground Waste Glass–Carbide Lime Blends for Geotechnical Uses. J. Mater. Civ. Eng. 2021, 33, 04021284. [Google Scholar] [CrossRef]
  17. Grigoleto, F.M.; Costa, A.G.M.; Bezerra, A.C.d.S. Compostos Na Ativação Alcalina Em Sistemas Binários Entre Resíduos Cerâmicos e Escória de Alto Forno. ENTAC 2024, 20, 1–12. [Google Scholar] [CrossRef]
  18. Thejas, H.K.; Hossiney, N. Alkali-Activated Bricks Made with Mining Waste Iron Ore Tailings. Case Stud. Constr. Mater. 2022, 16, e00973. [Google Scholar] [CrossRef]
  19. Silva, K.D.D.C.E.; Alvarenga, H.B.A.; Rocha, S.F.; Peixoto, R.A.F.; Brigolini, G.J.S. Synthesis and Properties of Alkali-activated Iron Ore Tailings Blended with Metakaolin. Int. J. Appl. Ceram. Technol. 2023, 20, 2817–2828. [Google Scholar] [CrossRef]
  20. Li, K.; Deng, J.; Zhu, Y.; Zhang, W.; Zhang, T.; Tian, C.; Ma, J.; Shao, Y.; Yang, Y.; Shao, Y. Utilization of Municipal Solid Waste Incineration Fly Ash with Different Pretreatments with Gold Tailings and Coal Fly Ash for Environmentally Friendly Geopolymers. Waste Manag. 2025, 194, 342–352. [Google Scholar] [CrossRef]
  21. Pollon, R.; Müller, C.; Pelissaro, D.T.; Prietto, P.D.M.; Korf, E.P. Alkali-Activated Materials Using Sugarcane Bagasse Ash: A Bibliometric Review. In Environmental Geotechnics: Waste and Geotechnical Stabilization; Korf, E.P., Prietto, P.D.M., Müller, C., Ferrazzo, S.T., Eds.; Nova Science Publishers: New York, NY, USA, 2024. [Google Scholar]
  22. Li, Z.; Wang, X.; Wang, S.; Feng, X. Study on Improving the Properties of Alkali-Activated Materials by Using Corncob Ash. ACS Omega 2025, 10, 16291–16299. [Google Scholar] [CrossRef]
  23. Huo, Y.; Huang, J.; Lu, D.; Han, X.; Sun, H.; Liu, T.; Wang, J.; Wang, F.; Tan, P.; Wang, M.; et al. Durability of Alkali-Activated Slag Concrete Incorporating Silica Fume and Rice Husk Ash. J. Build. Eng. 2023, 78, 107637. [Google Scholar] [CrossRef]
  24. Hossain, M.M.; Karim, M.R.; Elahi, M.M.A.; Islam, M.N.; Zain, M.F.M. Long-Term Durability Properties of Alkali-Activated Binders Containing Slag, Fly Ash, Palm Oil Fuel Ash and Rice Husk Ash. Constr. Build. Mater. 2020, 251, 119094. [Google Scholar] [CrossRef]
  25. Lei, Z.; Wang, E.; Li, Z.; Shi, X. Ultrafine Rice Husk Ash in Alkali-Activated Slag Systems: Synergistic Modulation of Si/Ca and Si/Al Ratios to Improve Mechanical Performance and Dimensional Stability. Constr. Build. Mater. 2025, 492, 142969. [Google Scholar] [CrossRef]
  26. Kekez, S.; Nováková, I.; Lach, M.; Setlak, K.; Fiala, L.; Přikryl, J.; Furtos, G.; Petean, I.; Alexandersson, K.F.; Baronins, J.; et al. Waste Valorization for Fabrication of Geopolymers. Case Stud. Constr. Mater. 2025, 22, e04388. [Google Scholar] [CrossRef]
  27. Liu, J.; Xie, G.; Wang, Z.; Li, Z.; Fan, X.; Jin, H.; Zhang, W.; Xing, F.; Tang, L. Synthesis of Geopolymer Using Municipal Solid Waste Incineration Fly Ash and Steel Slag: Hydration Properties and Immobilization of Heavy Metals. J. Environ. Manag. 2023, 341, 118053. [Google Scholar] [CrossRef]
  28. Saldanha, R.B.; Da Rocha, C.G.; Caicedo, A.M.L.; Consoli, N.C. Technical and Environmental Performance of Eggshell Lime for Soil Stabilization. Constr. Build. Mater. 2021, 298, 123648. [Google Scholar] [CrossRef]
  29. Krogel, M.; Müller, C.; Esposito, M.; Korf, E.P. The State of the Art of Alkaline Cementation: Waste Glass from Photovoltaic Modules as a New Precursor. In Advances in Environmental Research; Daniels, J.A., Ed.; Nova Science Publishers, Inc.: New York, NY, USA, 2025; Volume 106, pp. 65–92. [Google Scholar]
  30. Santos, C.P.D.; Bruschi, G.J.; Mattos, J.R.G.; Consoli, N.C. Stabilization of Gold Mining Tailings with Alkali-Activated Carbide Lime and Sugarcane Bagasse Ash. Transp. Geotech. 2022, 32, 100704. [Google Scholar] [CrossRef]
  31. CONAB (Companhia Nacional de Abastecimento). Safra 2024/25 de Cana-de-Açúcar Encerra Com Produção Estimada Em 676.96 Milhões de Toneladas. Available online: https://www.gov.br/conab/pt-br/assuntos/noticias/safra-2024-25-de-cana-de-acucar-encerra-com-producao-estimada-em-676-96-milhoes-de-toneladas (accessed on 29 July 2025).
  32. Duarte, J.B. Estudo da Adição Conjunta da Cinza do Bagaço da Cana-de-Açúcar e do Resíduo Cerâmico na Produção de Tijolos Maciços de Solo-Aglomerante(s). Ph.D. Thesis, Universidade Federal do Rio Grande do Norte, Centro de Ciências Exatas e da Terra, Natal, Brazil, 2020. [Google Scholar]
  33. Memon, S.A.; Javed, U.; Shah, M.I.; Hanif, A. Use of Processed Sugarcane Bagasse Ash in Concrete as Partial Replacement of Cement: Mechanical and Durability Properties. Buildings 2022, 12, 1769. [Google Scholar] [CrossRef]
  34. Garcia-Perez, T.; Ortiz-Ulloa, J.A.; Jara-Cobos, L.E.; Pelaez-Samaniego, M.R. Adding Value to Sugarcane Bagasse Ash: Potential Integration of Biogas Scrubbing with Vinasse Anaerobic Digestion. Sustainability 2023, 15, 15218. [Google Scholar] [CrossRef]
  35. Sousa, L.N.; Figueiredo, P.F.; França, S.; De Moura Solar Silva, M.V.; Borges, P.H.R.; Bezerra, A.C.D.S. Effect of Non-Calcined Sugarcane Bagasse Ash as an Alternative Precursor on the Properties of Alkali-Activated Pastes. Molecules 2022, 27, 1185. [Google Scholar] [CrossRef]
  36. Le, D.-H.; Sheen, Y.-N.; Lam, M.N.-T. Potential Utilization of Sugarcane Bagasse Ash for Developing Alkali-Activated Materials. J. Sustain. Cem.-Based Mater. 2022, 11, 199–209. [Google Scholar] [CrossRef]
  37. Tonini De Araújo, M.; Ferrazzo, S.T.; Bruschi, G.J.; Silva, G.J.B.; Consoli, N.C. Strength, Mineralogy, Microstructure, and Statistical Analysis of Alkali-Activated Sugarcane Bagasse Ash–Eggshell Lime Pastes. J. Mater. Civ. Eng. 2023, 35, 04023107. [Google Scholar] [CrossRef]
  38. Lima, V.M.E.; Estolano, A.M.L.; Almeida, Y.M.B.; Henrique, M.A.; Araújo, F.W.C.; Melo Neto, A.A. Mechanical, Microstructural and Energetic Evaluation of Conventional and One-Part Alkali-Activated Mixtures with Raw Sugarcane Bagasse Ash. Constr. Build. Mater. 2023, 394, 132168. [Google Scholar] [CrossRef]
  39. Iqbal, M.; Ashraf, M.; Alkhattabi, L.; Nazar, S.; Alam, J.; Alabduljabbar, H.; Husnain, A. Development of Sustainable Alkali Activated Composite Incorporated with Sugarcane Bagasse Ash and Polyvinyl Alcohol Fibers. PLoS ONE 2024, 19, e0307103. [Google Scholar] [CrossRef]
  40. Saldanha, R.B.; Scheuermann Filho, H.C.; Mallmann, J.E.C.; Consoli, N.C.; Reddy, K.R. Physical–Mineralogical–Chemical Characterization of Carbide Lime: An Environment-Friendly Chemical Additive for Soil Stabilization. J. Mater. Civ. Eng. 2018, 30, 06018004. [Google Scholar] [CrossRef]
  41. Pelisser, G.; Ferrazzo, S.T.; Mota, J.D.; Dos Santos, C.P.; Pelisser, C.; Rosa, F.D.; Korf, E.P. Rice Husk Ash-Carbide Lime as an Alternative Binder for Waste Foundry Sand Stabilization. Environ. Sci. Pollut. Res. 2023, 30, 42176–42191. [Google Scholar] [CrossRef] [PubMed]
  42. Kampala, A.; Horpibulsuk, S. Engineering Properties of Silty Clay Stabilized with Calcium Carbide Residue. J. Mater. Civ. Eng. 2013, 25, 632–644. [Google Scholar] [CrossRef]
  43. Othman, A.; Sulaiman, A.; Sulaiman, S.K. Carbide Lime in Acid Mine Drainage Treatment. J. Water Process Eng. 2017, 15, 31–36. [Google Scholar] [CrossRef]
  44. Kaur, N.; Kumar, R.; Kesari, K.K.; Gupta, P.K.; Singh, A. Synthesis and Characterization of Nano-Hydroxyapatite from Carbide Lime Waste through a Green Conversion Approach. Nano-Struct. Nano-Objects 2025, 41, 101433. [Google Scholar] [CrossRef]
  45. Servi, S.; Lotero, A.; Silva, J.P.S.; Bastos, C.; Consoli, N.C. Mechanical Response of Filtered and Compacted Iron Ore Tailings with Different Cementing Agents: Focus on Tailings-Binder Mixtures Disposal by Stacking. Constr. Build. Mater. 2022, 349, 128770. [Google Scholar] [CrossRef]
  46. Forster, A.M.; Válek, J.; Hughes, J.J.; Pilcher, N. Lime Binders for the Repair of Historic Buildings: Considerations for CO2 Abatement. J. Clean. Prod. 2020, 252, 119802. [Google Scholar] [CrossRef]
  47. Consoli, N.C.; Silvano, L.W.; Lotero, A.; Scheuermann Filho, H.C.; Moncaleano, C.J.; Cristelo, N. Key Parameters Establishing Alkali Activation Effects on Stabilized Rammed Earth. Constr. Build. Mater. 2022, 345, 128299. [Google Scholar] [CrossRef]
  48. Bruschi, G.J.; Dos Santos, C.P.; Tonini De Araújo, M.; Ferrazzo, S.T.; Marques, S.F.V.; Consoli, N.C. Green Stabilization of Bauxite Tailings: Mechanical Study on Alkali-Activated Materials. J. Mater. Civ. Eng. 2021, 33, 06021007. [Google Scholar] [CrossRef]
  49. Ferrazzo, S.T.; Levandoski, W.M.K.; Piovesan, M.A.; Korf, E.P. Stabilization of Iron Ore Tailings with Alkaline Cements. In Environmental Geotechnics: Waste and Geotechnical Stabilization; Korf, E.P., Prietto, P.D.M., Müller, C., Ferrazzo, S.T., Eds.; Nova Science Publishers: New York, NY, USA, 2024. [Google Scholar]
  50. Consoli, N.C.; Leon, H.B.; Da Silva Carretta, M.; Daronco, J.V.L.; Lourenço, D.E. The Effects of Curing Time and Temperature on Stiffness, Strength and Durability of Sand-Environment Friendly Binder Blends. Soils Found. 2019, 59, 1428–1439. [Google Scholar] [CrossRef]
  51. Ferrazzo, S.T.; Tonini De Araújo, M.; Bruschi, G.J.; Chaves, H.M.; Korf, E.P.; Consoli, N.C. Mechanical and Environmental Behavior of Waste Foundry Sand Stabilized with Alkali-Activated Sugar Cane Bagasse Ash-Eggshell Lime Binder. Constr. Build. Mater. 2023, 383, 131313. [Google Scholar] [CrossRef]
  52. NBR 10005; Procedimento Para Obtenção de Extrato Lixiviado de Resíduos Sólidos. Associação Brasileira de Normas Técnicas (ABNT): Rio de Janeiro, Brazil, 2004.
  53. NBR 10006; Procedimento Para Obtenção de Extrato Solubilizado de Resíduos Sólidos. Associação Brasileira de Normas Técnicas (ABNT): Rio de Janeiro, Brazil, 2004.
  54. NBR 10004; Resíduos Sólidos—Classificação. Associação Brasileira de Normas Técnicas (ABNT): Rio de Janeiro, Brazil, 2004.
  55. Zahmak, A.; Abdallah, M.; Jarah, B.; Arab, M.G. Environmental Performance of Alkali-Activated Binders for Ground Improvement. Transp. Geotech. 2021, 31, 100631. [Google Scholar] [CrossRef]
  56. Ferrazzo, S.T.; Tonini De Araújo, M.; Consoli, N.C. Which Solution Is More Sustainable: Waste Foundry Sand Stabilized with Alkali-Activated Binder or Portland Cement? J. Build. Eng. 2024, 84, 108448. [Google Scholar] [CrossRef]
  57. Consoli, N.C.; Daassi-Gli, C.A.P.; Ruver, C.A.; Lotero, A.; Scheuermann Filho, H.C.; Moncaleano, C.J.; Lourenço, D.E. Lime–Ground Glass–Sodium Hydroxide as an Enhanced Sustainable Binder Stabilizing Silica Sand. J. Geotech. Geoenviron. Eng. 2021, 147, 06021011. [Google Scholar] [CrossRef]
  58. ASTM C39/C39M-21; Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. ASTM International: West Conshohocken, PA, USA, 2023.
  59. Caicedo, A.M.L. Melhoramento de Um Solo Granular Por Ativação Alcalina de Resíduos de Cerâmica Vermelha e Cal de Carbureto. Doctoral’s Thesis (Civil Engineering), Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, 2020. [Google Scholar]
  60. Ferreira, F.A.; Desir, J.M.; Lima, G.E.S.D.; Pedroti, L.G.; Carvalho, J.M.F.D.; Lotero, A.; Consoli, N.C. Evaluation of Mechanical and Microstructural Properties of Eggshell Lime/Rice Husk Ash Alkali-Activated Cement. Constr. Build. Mater. 2023, 364, 129931. [Google Scholar] [CrossRef]
  61. Zhang, H.-Y.; Liu, J.-C.; Wu, B. Mechanical Properties and Reaction Mechanism of One-Part Geopolymer Mortars. Constr. Build. Mater. 2021, 273, 121973. [Google Scholar] [CrossRef]
  62. Pompermaier, C.L.; Ferrazzo, S.T.; Levandoski, W.M.K.; Bruschi, G.J.; Prietto, P.D.M.; Korf, E.P. Stabilization of Waste Foundry Sand with Alkali-Activated Binder: Mechanical Behavior, Microstructure and Leaching. Constr. Build. Mater. 2024, 444, 137772. [Google Scholar] [CrossRef]
  63. Queiróz, L.C.; Batista, L.L.S.; Souza, L.M.P.; Lima, M.D.; Danieli, S.; Bruschi, G.J.; Bergmann, C.P. Alkali-Activated System of Carbide Lime and Rice Husk for Granular Soil Stabilisation. Proc. Inst. Civ. Eng.-Ground Improv. 2023, 176, 279–294. [Google Scholar] [CrossRef]
  64. Burciaga-Díaz, O.; Escalante-García, J.I.; Magallanes-Rivera, R.X. Compressive Strength and Microstructural Evolution of Metakaolin Geopolymers Exposed at High Temperature. Rev. ALCONPAT 2015, 5, 58–72. [Google Scholar] [CrossRef]
  65. Lei, J.; Law, W.W.; Yang, E.-H. Effect of Calcium Hydroxide on the Alkali-Silica Reaction of Alkali-Activated Slag Mortars Activated by Sodium Hydroxide. Constr. Build. Mater. 2021, 272, 121868. [Google Scholar] [CrossRef]
  66. Yip, C.K.; Lukey, G.C.; Van Deventer, J.S.J. The Coexistence of Geopolymeric Gel and Calcium Silicate Hydrate at the Early Stage of Alkaline Activation. Cem. Concr. Res. 2005, 35, 1688–1697. [Google Scholar] [CrossRef]
  67. Corrêa-Silva, M.; Miranda, T.; Rouainia, M.; Araújo, N.; Glendinning, S.; Cristelo, N. Geomechanical Behaviour of a Soft Soil Stabilised with Alkali-Activated Blast-Furnace Slags. J. Clean. Prod. 2020, 267, 122017. [Google Scholar] [CrossRef]
  68. Moukannaa, S.; Bagheri, A.; Benzaazoua, M.; Sanjayan, J.G.; Pownceby, M.I.; Hakkou, R. Elaboration of Alkali Activated Materials Using a Non-Calcined Red Clay from Phosphate Mines Amended with Fly Ash or Slag: A Structural Study. Mater. Chem. Phys. 2020, 256, 123678. [Google Scholar] [CrossRef]
  69. Li, W.; Yi, Y. Use of Carbide Slag from Acetylene Industry for Activation of Ground Granulated Blast-Furnace Slag. Constr. Build. Mater. 2020, 238, 117713. [Google Scholar] [CrossRef]
  70. Yusuf, M.O. Bond Characterization in Cementitious Material Binders Using Fourier-Transform Infrared Spectroscopy. Appl. Sci. 2023, 13, 3353. [Google Scholar] [CrossRef]
  71. Wang, Y.; Gong, Y.; Lin, N.; Jiang, H.; Wei, X.; Liu, N.; Zhang, X. Cellulose Hydrogel Coated Nanometer Zero-Valent Iron Intercalated Montmorillonite (CH-MMT-nFe0) for Enhanced Reductive Removal of Cr(VI): Characterization, Performance, and Mechanisms. J. Mol. Liq. 2022, 347, 118355. [Google Scholar] [CrossRef]
  72. Vicent, M.; Criado, M.; García-Ten, J. Alkali-Activated Materials Obtained from Asphalt Fillers and Fluorescent Lamps Wastes. J. Clean. Prod. 2019, 215, 343–353. [Google Scholar] [CrossRef]
  73. Moukannaa, S.; Loutou, M.; Benzaazoua, M.; Vitola, L.; Alami, J.; Hakkou, R. Recycling of Phosphate Mine Tailings for the Production of Geopolymers. J. Clean. Prod. 2018, 185, 891–903. [Google Scholar] [CrossRef]
  74. Jain, B.; Sancheti, G.; Jain, V. FTIR Analysis of Silica Fume and Iron Dust Added Concrete. Mater. Today Proc. 2022, 60, 777–781. [Google Scholar] [CrossRef]
  75. García-Lodeiro, I.; Fernández-Jiménez, A.; Blanco, M.T.; Palomo, A. FTIR Study of the Sol–Gel Synthesis of Cementitious Gels: C–S–H and N–A–S–H. J. Sol-Gel Sci. Technol. 2008, 45, 63–72. [Google Scholar] [CrossRef]
  76. García Lodeiro, I.; Fernández-Jimenez, A.; Palomo, A.; Macphee, D.E. Effect on Fresh C-S-H Gels of the Simultaneous Addition of Alkali and Aluminium. Cem. Concr. Res. 2010, 40, 27–32. [Google Scholar] [CrossRef]
  77. García-Lodeiro, I.; Fernández-Jiménez, A.; Palomo, A.; Macphee, D.E. Effect of Calcium Additions on N–A–S–H Cementitious Gels. J. Am. Ceram. Soc. 2010, 93, 1934–1940. [Google Scholar] [CrossRef]
  78. Kaze, R.C.; Beleuk À Moungam, L.M.; Fonkwe Djouka, M.L.; Nana, A.; Kamseu, E.; Chinje Melo, U.F.; Leonelli, C. The Corrosion of Kaolinite by Iron Minerals and the Effects on Geopolymerization. Appl. Clay Sci. 2017, 138, 48–62. [Google Scholar] [CrossRef]
  79. Dal Poggetto, G.; D’Angelo, A.; Blanco, I.; Piccolella, S.; Leonelli, C.; Catauro, M. FT-IR Study, Thermal Analysis, and Evaluation of the Antibacterial Activity of a MK-Geopolymer Mortar Using Glass Waste as Fine Aggregate. Polymers 2021, 13, 2970. [Google Scholar] [CrossRef] [PubMed]
  80. Criado, M.; Fernández-Jiménez, A.; Palomo, A.; Sobrados, I.; Sanz, J. Effect of the SiO2/Na2O Ratio on the Alkali Activation of Fly Ash. Part II: 29Si MAS-NMR Survey. Microporous Mesoporous Mater. 2008, 109, 525–534. [Google Scholar] [CrossRef]
  81. Mabroum, S.; Garcia-Lodeiro, I.; El Machi, A.; Chhaiba, S.; Taha, Y.; Benzaazoua, M.; Blanco-Varela, M.T.; Hakkou, R. Acid Resistance of Alkali-Activated Binders Based on Clays from Phosphate Mining by-Products. J. Build. Eng. 2024, 95, 110106. [Google Scholar] [CrossRef]
  82. Shagñay, S.; Garcia-Lodeiro, I.; Velasco, F.; Bautista, A.; Torres-Carrasco, M. Mineralogical and Microstructural Changes in Alkali-Activated and Hybrid Materials Exposed to Accelerated Leaching. J. Build. Eng. 2023, 64, 105733. [Google Scholar] [CrossRef]
  83. Liu, T.; Chen, Y.; Yuan, B.; Zhuang, W.; Brouwers, H.J.H.; Yu, Q. Sodium Aluminate Activated Waste Glass: Reduced Efflorescence Behavior by C(N)−A−S−H Transformation. Cem. Concr. Res. 2024, 181, 107527. [Google Scholar] [CrossRef]
  84. Puertas, F.; Fernández-Jiménez, A.; Blanco-Varela, M.T. Pore Solution in Alkali-Activated Slag Cement Pastes. Relation to the Composition and Structure of Calcium Silicate Hydrate. Cem. Concr. Res. 2004, 34, 139–148. [Google Scholar] [CrossRef]
  85. VROM—Ministerie van Volksuisveting Ruimtelijke Ordening en Milieubeheer. Dutch Target and Intervention Values. In ANNEXES Circular on Target Values and Intervention Values for Soil Remediation; VROM: The Hague, The Netherlands, 2000. [Google Scholar]
  86. RESOLUÇÃO No 420/2009; Dispõe Sobre Critérios e Valores Orientadores de Qualidade Do Solo Quanto à Presença de Substâncias Químicas e Estabelece Diretrizes Para o Gerenciamento Ambiental de Áreas Contaminadas Por Essas Substâncias Em Decorrência de Atividades Antrópicas. CONAMA (Conselho Nacional do Meio Ambiente): Brasília, Brazil, 2009.
  87. Komonweeraket, K.; Cetin, B.; Benson, C.H.; Aydilek, A.H.; Edil, T.B. Leaching Characteristics of Toxic Constituents from Coal Fly Ash Mixed Soils under the Influence of pH. Waste Manag. 2015, 38, 174–184. [Google Scholar] [CrossRef] [PubMed]
  88. Levandoski, W.M.K.; Ferrazzo, S.T.; Piovesan, M.A.; Bruschi, G.J.; Consoli, N.C.; Korf, E.P. Long-Term Performance: Strength and Metal Encapsulation in Alkali-Activated Iron Ore Tailings. Environ. Sci. Pollut. Res. 2024, 31, 47071–47083. [Google Scholar] [CrossRef]
  89. Moffett, D.; Smith, C.; Stevens, Y.-W. Toxicological Profile for Barium and Barium Compounds; U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (US): Atlanta, GA, USA, 2007. [Google Scholar]
  90. USEPA (United States Environmental Protection Agency). Ground Water and Drinking Water: National Primary Drinking Water Regulations; USEPA: Washington, DC, USA, 2024. [Google Scholar]
  91. Serjun, V.Z.; Mladenovič, A.; Mirtič, B.; Meden, A.; Ščančar, J.; Milačič, R. Recycling of Ladle Slag in Cement Composites: Environmental Impacts. Waste Manag. 2015, 43, 376–385. [Google Scholar] [CrossRef] [PubMed]
  92. Palacios, M.; Palomo, A. Alkali-Activated Fly Ash Matrices for Lead Immobilisation: A Comparison of Different Leaching Tests. Adv. Cem. Res. 2004, 16, 137–144. [Google Scholar] [CrossRef]
  93. Vu, T.H.; Gowripalan, N. Mechanisms of Heavy Metal Immobilisation Using Geopolymerisation Techniques—A Review. J. Adv. Concr. Technol. 2018, 16, 124–135. [Google Scholar] [CrossRef]
  94. Zhang, Y.; Cetin, B.; Likos, W.J.; Edil, T.B. Impacts of pH on Leaching Potential of Elements from MSW Incineration Fly Ash. Fuel 2016, 184, 815–825. [Google Scholar] [CrossRef]
Constrmater 05 00079 g001
Figure 1. Particle size distribution curve of SCBA and CL [37,48].
Figure 1. Particle size distribution curve of SCBA and CL [37,48].
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Figure 2. XRD pattern of SCBA and CL [37,48].
Figure 2. XRD pattern of SCBA and CL [37,48].
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Figure 3. Unconfined compressive strength (UCS) as a function of curing time for: (a) 1.0 M, (b) 1.5 M, (c) 2.0 M, and (d) 2.5 M NaOH molarity.
Figure 3. Unconfined compressive strength (UCS) as a function of curing time for: (a) 1.0 M, (b) 1.5 M, (c) 2.0 M, and (d) 2.5 M NaOH molarity.
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Figure 4. Pareto chart of variable influence.
Figure 4. Pareto chart of variable influence.
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Figure 5. Main effects of the studied variables on average UCS.
Figure 5. Main effects of the studied variables on average UCS.
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Figure 6. Contour surface between the two most significant variables (curing time and SCBA/CL ratio).
Figure 6. Contour surface between the two most significant variables (curing time and SCBA/CL ratio).
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Figure 7. (a) SEM image at 1000× magnification of sample 3D-1.5M-80/20-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
Figure 7. (a) SEM image at 1000× magnification of sample 3D-1.5M-80/20-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
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Figure 8. (a) SEM image at 1000× magnification of sample 7D-1.5M-80/20-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
Figure 8. (a) SEM image at 1000× magnification of sample 7D-1.5M-80/20-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
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Figure 9. (a) SEM image at 1000× magnification of sample 28D-2M-70/30-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
Figure 9. (a) SEM image at 1000× magnification of sample 28D-2M-70/30-TWO, and corresponding (b) chemical map obtained by EDS; (c) elemental distribution; (d) EDS spectrum; and (e) SEM image at 5000× magnification showing gel formation areas.
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Figure 10. XRD patterns of all selected samples showing the identified minerals.
Figure 10. XRD patterns of all selected samples showing the identified minerals.
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Figure 11. FTIR spectra of the six selected samples with identification of chemical bonds and corresponding alkali-activation gels.
Figure 11. FTIR spectra of the six selected samples with identification of chemical bonds and corresponding alkali-activation gels.
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Table 1. Material properties.
Table 1. Material properties.
PropertyMaterials
SCBACL
Specific gravity2.08-
Surface area (m2/g)125.1526.2
Environmental classificationNon-hazardous—non-inert—Class II A wasteNon-hazardous—inert—Class II B waste
Fine sand (%)—0.06 ≤ d < 0.2 mm8.880.94
Silt (%)—0.002 ≤ d < 0.06 mm90.1396.43
Clay (%)—d < 0.002 mm0.992.63
ReferenceTonini de Araújo et al. [37]; Ferrazzo et al. [51]Bruschi et al. [48]
Table 2. Oxide composition of SCBA and CL (wt.%).
Table 2. Oxide composition of SCBA and CL (wt.%).
MaterialSiO2Al2O3Fe2O3MnOMgOCaONa2OK2OTiO2P2O5SO3SrOLOIReference
SCBA60.655.7613.870.451.971.400.222.904.141.26--7.38Tonini de Araújo et al. [37]
CL1.100.280.18-0.1171.10----0.280.1326.8Bruschi et al. [48]
Table 3. Controlled variables and their levels.
Table 3. Controlled variables and their levels.
VariableLevel
Curing time (days)3, 7, and 28
Activator concentration (M)1; 1.5; 2.0; 2.5
Ash/lime ratio9.00; 4.00; 2.33; 1.5
Mixing methodOne Part and Two Part
Table 4. Selected specimens for chemical, mineralogical, and leaching analyses.
Table 4. Selected specimens for chemical, mineralogical, and leaching analyses.
SpecimenCuring Time (Days)Ash/Lime RatioActivator Concentration (M)Mixing Method
134.001.5One Part
234.001.5Two Part
374.001.5One Part
474.001.5Two Part
5282.332.0One Part
6282.332.0Two Part
Table 5. Comparison of curing times using Tukey’s test.
Table 5. Comparison of curing times using Tukey’s test.
Curing Time (Days)Average UCS (MPa)Grouping 1
280.904A
70.483B
30.375C
1 Means that do not share a letter are statistically different.
Table 6. Comparison of SCBA/CL ratios using Tukey’s test.
Table 6. Comparison of SCBA/CL ratios using Tukey’s test.
Ash/Lime RatioAverage UCS (MPa)Grouping 1
2.330.686A
4.000.665A
1.500.587B
9.000.413C
1 Means that do not share a letter are statistically different.
Table 7. Comparison of activator concentration using Tukey’s test.
Table 7. Comparison of activator concentration using Tukey’s test.
Activator Concentration (M)Average UCS (MPa)Grouping 1
1.50.633A
2.00.612AB
1.00.556B
2.50.550B
1 Means that do not share a letter are statistically different.
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MDPI and ACS Style

Pollon, R.; Bruschi, G.J.; Ferrazzo, S.T.; Fornari, A.C.; Lazzari, E.R.; Prietto, P.D.M.; Pavan Korf, E. Performance and Environmental Assessment of Alkali-Activated Cements from Agricultural and Industrial Residues. Constr. Mater. 2025, 5, 79. https://doi.org/10.3390/constrmater5040079

AMA Style

Pollon R, Bruschi GJ, Ferrazzo ST, Fornari AC, Lazzari ER, Prietto PDM, Pavan Korf E. Performance and Environmental Assessment of Alkali-Activated Cements from Agricultural and Industrial Residues. Construction Materials. 2025; 5(4):79. https://doi.org/10.3390/constrmater5040079

Chicago/Turabian Style

Pollon, Rafaela, Giovani Jordi Bruschi, Suéllen Tonatto Ferrazzo, Arielle Cristina Fornari, Eduarda Razador Lazzari, Pedro Domingos Marques Prietto, and Eduardo Pavan Korf. 2025. "Performance and Environmental Assessment of Alkali-Activated Cements from Agricultural and Industrial Residues" Construction Materials 5, no. 4: 79. https://doi.org/10.3390/constrmater5040079

APA Style

Pollon, R., Bruschi, G. J., Ferrazzo, S. T., Fornari, A. C., Lazzari, E. R., Prietto, P. D. M., & Pavan Korf, E. (2025). Performance and Environmental Assessment of Alkali-Activated Cements from Agricultural and Industrial Residues. Construction Materials, 5(4), 79. https://doi.org/10.3390/constrmater5040079

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