Physical–mechanical behavior of cement and lime mortars with mixed aggregate of sand and crushed recycled glass

Abstract

Mortars made of mixed cement and lime (mixed mortar) have good mechanical behaviour and improve adhesion to other materials. In this study, mixed mortars have been prepared and characterized with a partial replacement of 25% of the natural aggregate by recycled crushed glass. The physical and mechanical properties have been evaluated and the ultrasonic transmission rates have been determined. The Student's t-test was used to statistically analyze the outcomes. Internal structures and potential mineralogical alterations were analyzed by SEM. The characteristics of these mortars were compared with those of reference ones.

The resistance results have revealed an improvement of the mixed mortar with glass compared to the reference mixed mortar of 14% in bending and 10% in compression. Moreover, a decrease in Young's modulus has been shown in mixed mortars with glass in comparison with the reference mixed mortars, although the addition of glass does not imply statistically significant differences.

Resumen

Los morteros compuestos por cemento y cal (mortero mixto) presentan un buen comportamiento mecánico y mejoran la adhesión a otros materiales. En este estudio se han preparado y caracterizado morteros mixtos con una sustitución parcial del 25% del árido natural por vidrio triturado reciclado. Se han evaluado las propiedades físicas y mecánicas y se han determinado los índices de transmisión de ultrasonidos. Se utilizó la prueba t de Student para analizar estadísticamente los resultados. Las estructuras internas y las posibles alteraciones mineralógicas se analizaron mediante SEM. Las características de estos morteros se compararon con las de morteros de referencia.

Los resultados de resistencia han revelado una mejora del mortero mixto con vidrio en comparación con el mortero mixto de referencia de un 14% en flexión y de un 10% en compresión. Además, se ha observado una disminución del módulo de Young en los morteros mixtos con vidrio en comparación con los morteros mixtos de referencia, aunque la adición de vidrio no implica diferencias estadísticamente significativas.

Introduction

A popular method that strives to offer a positive environmental balance is the insertion of cement conglomerates of by-products and wastes of different kinds, so that the building sector assumes some of the waste it produces [1]. In this sense, incorporating by-products from other industrial processes unrelated to construction is a fascinating approach that promotes waste reuse and has the consequent environmental, technical and economic benefits [2,3]. One of the most efficient, cost-effective, innovative, and environmentally friendly ways to improve the performance of cement conglomerates is to use unusual waste materials.

Adequate standards and interdisciplinary partnerships between experts in the field of construction are urgently needed in order to promote the use of aggregates that contain waste in construction processes, commonly known as ‘green concrete’ [4]. In addition, it is essential to deepen the projects for the development of alternative binders and new construction products [5–7].

Currently, the most popular strategy is to replace aggregates with different recycled materials which has led to significant progress in the construction sector, thus reducing the need to extract virgin aggregates [8]. The circumstance arises that the partial replacement of natural aggregates by recycled aggregates tends to result in poorer resistances in mortars and concretes, although it is unrelated to the applications of the aforementioned product.

The mechanical behaviour of mortars is generally improved by recycled aggregates, albeit the degree of improvement varies depending on the properties of the aggregate and the ratios used [9,10]. Previous studies have shown that using specific recycled aggregates in lime and mixed cement mortars has a good impact and increases resistance. This enhancement is the result of the aggregate surface's alkaline activation effect, which allows the develop of pozzolanic reactions in the interfaces aggregates/paste due to the significant increase in solubility and dissolution rate of glass at high pH [11–13].

Mortars manufactured with cement and lime present an initial hydration of the calcium silicates and a progressive carbonation towards the core. Carbonation has very important structural consequences due to its direct effect on the physical and mechanical properties, causing a modification of the porous structure of the mortar. The core is kept moist in order to maintain its transpiration and plasticity properties [14,15]. As carbonation advances towards the core, calcium carbonate will form in the mortar from the reaction of atmospheric CO₂ with calcium hydroxide. For this to occur, the surface must be in a fresh state exposed to the air.

Carbonation is a spontaneous process that is affected by natural variables. It is caused by the diffusion of CO₂ that enters through the porous system [16]. The progress of carbonation from the surface to the interior of the mortar depends mainly on humidity, more favourable when it is between 50–70%. Above this limit, the pores are occupied, and CO₂ cannot enter the structure, and below this limit, the adequate conditions for the reaction to complete do not occur. In addition, carbonation is also influenced by the permeability and the concentration of CO₂ present in the atmosphere [17–19].

Regarding the use of waste as a substitute for natural aggregate, the incorporation of crushed glass as an aggregate provides added environmental value to the final products without negatively affecting their applicability. There are numerous studies that address the characteristics of mortars and concretes with incorporated glass as a replacement for fine aggregate [20,21]. The mechanical capacities of these products with respect to reference mortars made with natural aggregate are sufficient for the construction requirements of the mortars, the physical properties do not suffer relevant variations and the thermal behaviour improves in relation to the insulating capacity [1,22].

Glass is mainly composed of amorphous silica, it acts as an aggregate with chemical characteristics similar to a natural siliceous aggregate, incorporating a certain pozzolanic capacity, particularly powerful in small particles. The glass particles intrinsic reactivity is largely determined by the chemical composition and structure. Factors such as the ratio (CaO + MgO)/SiO₂ can be linked to the reactivity of the glasses, where lower degrees of polymerization usually improve their reactivity [23]. The presence of calcium hydroxide resulting from the hydration of the conglomerates makes it possible to reproduce reactions similar to those of cement. It has been verified an evident phenomenon in the interfacial transition zone (ITZ) between cement paste and aggregate, on the outer surface of the glass particles, where Ca(OH)₂ precipitates, pozzolanic reactions occur that results in the formation of hydrated calcium silicates [24,25]. The calcium hydroxide formed from the hydration of calcium silicates in cement would be insufficient to verify a significant mechanical improvement in cement mortars; however, the incorporation of lime as a component in mixed mortars increases the amount of calcium hydroxide with the capacity to react with reactive silica and develop significant modifications in the resistance values of mortars with crushed glass compared to reference mortars.

Based on the above data and considering the common use of lime as a component that improves the plasticity of cement mortars used in building, it seems relevant to study the chemical reactions produced by the incorporation of crushed glass as a fraction of the aggregate in the presence of Ca(OH)₂ derived from the alkaline activation of the glass, especially at the glass/paste ITZ.

The objective of this work is to carry out a comparative analysis of the physical and mechanical properties of cement mortars and cement and lime mortars with partial substitutions of crushed glass compared to the corresponding reference products made only with natural aggregate. The mineralogical composition and internal structure of the materials under study have been evaluated to analyze the factors that influence the differences in performance.

Materials and method

Two cement mortars specimens and two mixed mortars composed by cement and lime specimens have been manufactured, all of them have a 1:3 aggregate/binder ratio, considering this ratio as one of the most used in construction mortars. Regarding the cement mortars, one of them exclusively contains sand as aggregate (RCM) and the other incorporates a 25% partial replacement of sand with crushed glass with the same granulometry (CM25). In this regard, the percentage of replacement selected is a 25% due to previous studies that demonstrate a great performance of the mortar without altering the properties of the material [1]. Studies such as those by Mohajerani et al. or Park et al. highlight the variability in behaviour depending on the characteristics of the glass, although substitution levels of around 25% result in positive values across the range of physical and mechanical properties [20,26]. The studies by Quiong et al. also report a 10% improvement in mechanical properties for substitutions of 20% or more [27].

By contrast, the binder is composed by 2/3 cement and 1/3 lime in mixed mortars and, following the same criteria applied to the cement mortar, one of them contains exclusively sand as aggregate (RBM) and the other incorporates a partial replacement of 25% sand with crushed glass with the same granulometry (BM25).

The raw materials used in the manufacturing process have been:

• •

  CEBASA CEM II/A-L 42.5R. In accordance with the manufacturer's instructions, this cement is recommended for reinforced concrete and for environments of certain aggressiveness (http://www.cebasa.com[28]).

• •

  YEMACONSA CL 90 S hydrated lime.

• •

  Standardized sand supplied by the Eduardo Torroja Institute (CEN sand according to the UNE-EN 196-1:2018 standard).

• •

  Crushed glass from household waste, mostly common containers, this material was crushed in a jaw crusher and sieved to a particle size of less than 2 mm and its density is 2.5 g/cm³ like a conventional sand. To get an aggregate with a replacement of 25% of the same granulometry, it was dispersed via selective sieving in granulometric fractions identical to those of the standardized sand. Fig. 1 shows the particle size distribution curve compared with the maximum density curve.

  
  

  Fig. 1.

  Aggregate particle size of crushed glass.

The chemical compositions of the cement and crushed glass obtained by XRF are shown in Table 1.

Table 1.

Chemical composition obtained by XRF of major components expressed in percentages (%).

	SiO2	Al2O3	Fe2O3	MnO	MgO	CaO	Na2O	K2O	TiO2	P2O5	SO3	LOI
Cement	30.36	13.33	2.47	0.05	0.87	44.22	0.68	0.81	0.60	0.61	2.36	3.85
Glass	71.05	1.50	0.19	–	0.76	11.38	13.19	0.72	–	–	–	0.10

The dosage used for the manufacture of the specimens guarantees the plastic behaviour of the products according to the specifications of the UNE-EN-1015-3 standard [29]. This dosage is specified in Table 2.

Table 2.

Composition of the dosages used in the manufacture of mortars per batch.

	Cement (g)	Lime (g)	Sand (g)	Glass (g)	Water (g)	Water/binder ratio
RCM	900	–	2700	–	450	0.5
CM25	900	–	2025	675	450	0.5
RBM	600	300	2700	–	540	0.6
BM25	600	300	2025	675	540	0.6

Considering these dosages, series of 40 mm × 40 mm × 160 mm standardized specimens of each type of mortar were prepared, which were cured under optimal conditions of humidity (95%) and temperature (20 °C ± 2) for 28 days, in accordance with the specifications of the UNE-EN 196-1:2018 standard [30], being subsequently analyzed by carrying out different tests.

The experimental procedure used to characterize materials and products was:

• •

  Determination of the apparent density and open porosity of the samples using the vacuum method in accordance with the UNE-EN 1936 standard [31].

• •

  Determination of mechanical resistance of mortars to bending and compression according to the UNE-EN 196-1:2018 standard [27] standard with a load speed of 50 N/s until failure.

• •

  Mineralogical characterization of the mortars by means of X-ray diffraction, in a Bruker-AXS model D8I-A25 diffractometer, equipped with a Cu Kα filament (λ = 1.5405 Å), with a Bragg–Brentano θ–θ configuration, filter nickel detector and Lynxeye linear detector, using the powder technique.

• •

  Determination of the ultrasound transmission speed in accordance with the UNE-EN 14579:2005 [32] in the six test tubes of each type of mortar (RCM, CM25, RBM and BM25). For this, measurements were taken in the three spatial directions (Fig. 2), with the z-axis being the direction of compaction of the specimens, expressing the values obtained in m/s. Pundit Lab equipment from the Proceq company was used, equipped with 50 kHz cylindrical transducers.

  
  

  Fig. 2.

  Scheme for determination of ultrasonic velocities on the specimens.
• •

  In order to study the elastic deformability of the materials, the Young's modulus was obtained thanks to the results of density and ultrasonic speed:

where:

E – Young's modulus (Pascales).

v – ultrasonic transmission speed (m/s).

ρ – density (kg/m³).

• •

  To determine if there are significant differences in the mechanical strength, the values of ultrasonic velocity, and Young's modulus, between the reference samples and the samples with 25% glass aggregate, the Student's t test was used (i.e., compare RBM to BM25 and RCM to CM25) by establishing a significance level of α = 0.01 [33]. Therefore, if the p-value (significance) obtained in the t-test is less than 0.01 the difference in means is considered significant. This statistical model is valid for normal distributions with small sample sizes [34].

• •

  In order to evaluate the modifications in the internal structure of the materials, the study was carried out by scanning electron microscopy in a FEI-TENEO microscope equipped with an X-ray energy dispersion spectrometer (EDX) for microanalysis.

Results and discussion

Physical properties

This section summarizes the most relevant physical properties of the different mortars’ specimens manufactured in this work. Table 3 shows the descriptive statistics of the apparent density and open porosity values obtained by the different types of mortar after curing for 28 days.

Table 3.

Statistical data of physical properties.

	Apparent density (g/cm^3)				Open porosity (%)
	Average	CI 95%	SD	CV (%)	Average	CI 95%	SD	CV (%)
RCM	2.09	±0.0072	0.00894	0.43	19.83	±0.4382	0.54763	2.76
CM25	2.01	±0.0079	0.00983	0.49	21.65	±0.2648	0.33096	1.53
RBM	1.94	±0.0194	0.02422	1.25	24.92	±1.0642	1.32994	5.34
BM25	1.92	±0.0106	0.01329	0.69	24.83	±0.2773	0.34661	1.40

Confidence interval (CI); standard deviation (SD); coefficient of variation (CV).

After taking into account the impact of lime incorporation, the values for density and porosity obtained are within the expected limits. The coefficient of variation (CV) is defined as the ratio of the standard deviation to the mean. The coefficients of variation are less than 30% indicating that the samples are very homogeneous, and the average is representative of the data set [35].

The results of the physical properties of the cement mortar cured for 28 days show that by incorporating glass instead of sand, the apparent density decreases significantly (from 2.09 g/cm³ to 2.01 g/cm³; t(10) = 14.436, p = .000), while open porosity increases significantly (from 19.83% to 21.65%, t(10) = −6.980, p = .000). It may seem that going from 2.09 to 2.01 is a small difference, but it is significant because the density values are small values, and the t-test confirms this.

On the other hand, in the mixed mortar cured for 28 days, both the apparent density and the open porosity decrease slightly when glass is incorporated, substituting part of the sand (from 1.94 g/cm³ to 1.92 g/cm³, and from 24.92% to 24.83%). These variations were not significant, as confirmed by the Student's t test outcomes, t(10) = 1.625, p = .135, and t(10) = 0.149, p = .885 respectively.

All values obtained for density and porosity are within the expected ranges according to the type of material.

Mechanical properties

Table 4 shows the descriptive statistics of the bending and compression strength values obtained by the different types of mortar after curing for 28 days.

Table 4.

Statistical data on mechanical properties after 28-day cure.

	Bending strength (N/mm^2)				Compression strength (N/mm^2)
	Average	CI 95%	SD	CV (%)	Average	CI 95%	SD	CV (%)
RCM	5.80	±0.2277	0.28459	4.91	33.33	±1.2402	2.19188	6.58
CM25	4.60	±0.2399	0.29978	6.52	27.39	±1.2523	2.21324	8.08
RBM	0.98	±0.0987	0.08718	8.90	8.84	±0.9633	1.70256	19.26
BM25	1.21	±0.1338	0.15264	12.61	9.78	±0.5626	0.99433	10.17

Confidence interval (CI); standard deviation (SD); coefficient of variation (CV).

The values of the coefficients of variation (CV) are less than 30%, demonstrating the homogeneity of the samples and the accuracy of the arithmetic mean as a measure of the data set [35].

It is observed how the bending resistance of the reference cement mortar (RCM = 5.80 N/mm²) decreases when replacing 25% of sand with glass (CM25 = 4.60 N/mm²). This decrease is statistically significant, t(10) = 7.111, p = .000. On the contrary, the bending resistance of the reference mixed mortar (RBM = 1.26 N/mm²) increases when replacing 25% of sand for glass (BM25 = 1.44 N/mm²), although this increase is not statistically significant, t(10) = −0.499, p = .629.

Likewise, the compressive strength of the reference cement mortar (RCM = 33.33 N/mm²) decreases when replacing 25% of sand for glass (CM25 = 27.39 N/mm²) this decrease is statistically significant, t(22) = 6.611, p = .000. On the contrary, the bending resistance of the reference mixed mortar (RBM = 0.98 N/mm²) increases when replacing 25% of sand for glass (BM25 = 1.21 N/mm²), although this increase is not statistically significant, t(6) = −2.343, p = .058.

These results indicate that the mixed mortar show a higher relative improvement than the cement mortar when part of the sand is replaced by recycled glass, by improving its mechanical properties. This improvement suggests that the alkaline activation that occurs on the ITZ of the glass grains, favours the formation of calcium silicates in the presence of Ca(OH)₂ in higher quantities than those that would be formed by the simple hydration of the calcium silicates in the cement.

X-ray diffraction analysis

The diffractograms obtained for the four samples in their initial state (RCM, CM25, RBM, BM25) do not present relevant differences due to the fact that the glass does not provide any crystalline phase apart from the sand phase (Fig. 3). There is a majority presence of quartz and feldspars (anorthite and orthoclase) appear as minor components from the aggregate. Calcite is present in CM, a product of the initial carbonation of the portlandite (Ca(OH)₂) formed in the hydration of the cement; in the BM sample, the peaks are of greater intensity and their origin is found in the carbonation of the calcium hydroxide present in the original composition.

Fig. 3.

X-ray diffractograms of the analyzed samples (Qtz: quartz; Cal: calcite; Por: portlandite; An: anorthite; Or: orthoclase).

In CM samples, very low intensity peaks of anhydrous silicates that have not become hydrated with water are also detected. The gels formed by the hydration of the silicates usually present a low crystallinity that makes their detection difficult by XRD, in addition, due to the overlapping of the peaks, they are difficult to identify in the diffractogram [36].

In general, the presence of the amorphous CSH gel can be considered, which is identified by the rise of the diffractogram baseline in the 20–30° region.

Ultrasound speed tests

Table 5 shows the descriptive statistics of the ultrasound transmission speed and the Young's modulus in the different types of mortar studied after curing for 28 days. It shows that the incorporation of glass does not imply substantial modifications of the behaviour of the products in relation to the properties influencing the ultrasonic transmission speed and the mechanical behaviour expressed by the Young's modulus. The results of modulus, obtained using necessarily simplified criteria from the ultrasound test, may be less accurate than those obtained from vibration excitation by impact, although the trends obtained showed significant data [37].

Table 5.

Statistical data of ultrasonic transmission speed and Young's modulus.

	Ultrasonic transmission speed (m/s)				Young's modulus (N/mm^2)
	Average	CI 95%	SD	CV (%)	Average	CI 95%	SD	CV (%)
RCM	3461.60	±86.22	240.941	6.96	25.16	±1.2581	3.5159	13.97
CM25	3482.23	±55.42	154.879	4.45	24.42	±0.7749	2.1655	8.87
RBM	2790.97	±60.82	169.975	6.09	15.16	±0.6526	1.8237	12.03
BM25	2751.67	±54.24	151.578	5.51	14.58	±0.5703	1.5938	10.93

Confidence interval (CI); standard deviation (SD); coefficient of variation (CV).

These mortars do not strictly meet the criteria for being homogeneous and isotropic media; however, experience shows that the direction of compaction has no significant effect on the mechanical properties, and the ultrasonic transmission velocity values do not vary significantly depending on the axis of measurement [38].

The coefficients of variation (CV) values are excellent (10%) or good (20%). In any case, the CVs are less than 30%, indicating that the samples are homogeneous and the arithmetic mean is representative of the data set [35].

When comparing the ultrasound speed of the reference mortars and the mortars with 25% glass, it is shown that replacing sand for glass does not result in a significant change in ultrasound speed, whether the mortar is a reference mortar or a mixed one. Thus, in the cement mortar it goes from 3461.60 m/s (RCM) to 3482.23 m/s (CM25), t(58) = −0.395, p = .695, and in the mixed mortar it goes from 2790.97 m/s (RBM) to 2751.67 m/s (BM25), t(58) = 0.945, p = .348.

The Young's modulus does not change significantly when sand is replaced with glass, regardless of whether it is the cement mortar or the mixed mortar, as can be observed when comparing the reference mortars to the mortars with 25% glass. Thus the RCM goes from a Young's modulus of 25.16 N/mm² to 24.42 N/mm² in the CM25, t(58) = 0.977, p = .333, and the RBM goes from a module 15.16 N/mm² to 14.58 N/mm² in the BM25, t(58) = 1.297, p = .200.

Data analysis indicates that mixed mortars have a lower ultrasound transmission speed than both cement mortars, the RCM and the CM25. This circumstance is derived from the increase in porosity that the incorporation of lime into the batch entails. Thus, the mortar cured at 28 days goes from 3461.60 m/s of the RCM to 2790.97 m/s of the RBM and from 3482.23 m/s of the CM25 to 2751.67 m/s of the BM25. Being all these decreases in speed statistically significant as shown by the Student's t test, t(58) = 12.457, p = .000; t(58) = 18.465, p = .000, respectively.

It is clear that mixed mortars have a lower Young's modulus than both cement mortars, RCM and CM25, which implies greater deformability and ability to assume deformations. The reference mortar goes from a modulus of 25.16 N/mm² in the cement to 15.16 N/mm² in the mixed, and the mortar with glass goes from a modulus of 24.42 N/mm² in the cement to 14.58 N/mm² in the mixed, these decreases being statistically significant as corroborated by Student's t-test, t(58) = 13.833, p = .000; t(58) = 20.045, p = .000 respectively.

Study by scanning electron microscopy

The analysis by SEM has been carried out on samples in which the aggregate used has been exclusively glass. The limitation of the aggregate of the samples has been intended to ensure the interpretation of the images, verifying that the processes evaluated have been carried out between the cement paste or cement/lime and the glass grains, avoiding the uncertainty that occurs in the distinction of glass grains and those of natural aggregate, particularly in the study of ITZ, which are usually very heterogeneous regions of gradual transition and interstitial processes [39,40].

The observation of the images has revealed an evident similarity in the evolution of the samples of cement mortars and mixed mortars. The ITZ have clean edges and a high degree of aggregate-paste cohesion in both cases. It should be noted that the differences obtained in the density and porosity values are not enough different to reveal a discernible structural difference in the study by microscopy (Figs. 4A and B). Fig. 4B shows the areas where analyses of plate-like and filament-like structures were carried out (Table 6). Researches show the develop of new hydration products by the pozzolanic activity developed in the glass surface, particularly structures of small size which are smaller than the original hydration ones [41–43]. Plates and filaments structures observed by SEM were analyzed by EDX (Table 2). According to results, these structures may be attributed to calcium silicates.

Fig. 4.

Photomicrographs of the CM25 (A, C, and E) and BM25 (B, D, and F) samples. (A, B) Image of glass grains in the binder matrix (F: filaments, P: plates); (C, D) Development of hydrated crystalline phases; (E, F) Crystallizations of newly formed portlandite and calcium silicates from the glass aggregate.

Table 6.

EDX analysis of plates and filaments from Fig. 4B SEM image.

Element	Weight%
	Plates	Filaments
C K	5.01	2.06
O K	53.14	54.06
Mg K	0.40
Al K	1.41	0.79
Si K	12.93	6.23
Ca K	22.92	36.86
Fe K	0.79
Totals	100.00	100.00

Although they appear to be more continuous and homogenous in the cement mortar samples (Fig. 3C) than those seen in the mixed mortar (Fig. 3D), the production of hydrated silicates also takes place in both constructions with similar crystalline forms.

Finally, it should be noted that differences have been found in the calcium hydroxide formations identified in both cases. In the cement mortar samples, portlandite crystals can be seen scattered in the form of plates on the surface of the material (Fig. 3E). The portlandite plates do, however, appear crystallized in the interstices of the aggregate grains in the cement and glass mortar samples, together with filamentary structures classified as hydrated calcium silicates that develop on the glass surface (Fig. 3F).

Conclusions

The incorporation of crushed glass may represent a viable modification in the composition of the mortars, contributing an added value of sustainability. In the case of the mixed cement and lime mortars, trend towards improvement in mechanical properties has been revealed.

Apparently, the incorporation of glass does not imply relevant modifications of the physical properties. However, according to the statistical analysis of the results, these properties are significantly altered in cement mortars, increasing porosity and decreasing density, whereas in mixed mortars, the substitution of recycled glass for 25% of the aggregate has no effect on the physical characteristics.

Regarding the mechanical properties, a significant modification of these properties has been observed in the cement mortar. In the mixed mortar, replacing 25% of aggregate with recycled glass causes a slight positive effect. The incorporation of glass represents an improvement of 14.4% in bending strength and 10.6% in compressive strength. This improvement finds its justification in the formation of calcium silicates in the interstices added paste of the mixed mortars, due to the alkaline activation of the surface of the glass grains in the presence of calcium hydroxide. This circumstance has been observed in the images of the electron microscope.

Both in cement mortars and in the mixed mortar, the ultrasonic speed is not substantially altered by replacing a 25% of the aggregate with recycled glass. As happened with mechanical properties, the incorporation of glass has caused similar modifications in both cases with decreases in the Young's modulus of 3%. This effect may be also due to the reaction of glass silicates with calcium hydroxide.

The outcomes demonstrate that adding glass to lime and mixed cement mortars has a very different effect than adding glass to cement mortars. The mechanical capacities of cement mortars are slightly reduced, but behaviour in cement and lime mortars is generally better, supporting their usage in addition to the increased sustainability of construction materials manufactured by integrating crushed glass waste.

Acknowledgements

This work has been developed in collaboration with the PGC project ‘PID2023-147258OB-I00’ of the Spanish Ministry of Science and Innovation. The authors wish to express their gratitude to CITIUS at the University of Seville for the use of the laboratories for the characterization analyses.