Carbonation Depth Research Articles

Durability assessment of blended slag-fly ash geopolymer concrete in field conditions after 5 years

This study investigated the durability performance of a blended slag-fly ash geopolymer concrete slab exposed to outdoor field conditions for five years. The performance of the geopolymer slab was periodically assessed at two different intervals. During the assessment, ultrasonic pulse velocity (UPV) was performed to analyze the structural soundness. The cores were extracted and tested for strength, carbonation depth and transport parameters. With time, the UPV was improved from 4.17 km/s to 4.39 km/s which suggests densification of microstructure and correlated well with the reduction in the water permeability depths. Degradation of strength or efflorescence was not observed over time and the pH of the concrete was found to be 10.9 after five-year exposure. Microstructural studies revealed the formation of needle-like structures and the densification of the matrix with age. The investigation of the durability performance of geopolymer concrete is essential for the development of standard specifications for wider industrial applications.

Phase evolution and microstructure changes induced by accelerated carbonation in natural hydraulic lime paste with GGBFS addition

Carbonation is a primary factor driving the continuous improvement of the long-term performance of natural hydraulic lime (NHL). This research systematically examines the impact of accelerated carbonation (3 % CO2) on the carbonation depth, phase composition, microstructure, and compressive strength of hardened natural hydraulic lime (NHL) pastes mixed with different amounts of ground granulated blast furnace slag (GGBFS), termed as S-NHL. The findings show that the hydration reaction products of GGBFS and Ca(OH)2 (CH), such as C3AH10, C4AĈH11, and C-S-H, densify the microstructure of S-NHL, resulting in a decrease in carbonation depth with increasing GGBFS content. Accelerated carbonation (AC) promotes the rapid transformation of a significant quantity of CH into calcite in S-NHL, with the carbonation of CH occurring more readily than the carbonation of hydration reaction products. Throughout the AC process, NHL contains only calcite-type calcium carbonate. In contrast, after 28 days of AC, the carbonation of hydration reaction products such as C3AH10 and C-S-H in S-NHL produces a minor amount of aragonite and vaterite. AC continuously reduces the total pore volume and porosity of S-NHL, but the average pore diameter and most probable pore diameter initially decrease and then slightly increase. AC significantly reduces the large pores in S-NHL, ultimately resulting in pores predominantly composed of capillary pores (50–1000 nm). AC facilitates the development of compressive strength in S-NHL paste, with the increase in compressive strength being positively correlated with its CH content.

Enhancing carbonated mortar durability by electro-osmotic treatment of silane

Electro-osmotic treatment (EOT) of silane for enhancing the durability of carbonated mortar was investigated. During the EOT, silane was injected into carbonated mortar pores by applying an electric field, leading to deeper penetration depths. The durability enhancements of the carbonated mortar after EOT of silane were evaluated by examining water absorption, carbonation depth, sulfate resistance and chloride diffusion. The microscopic mechanism of the electro-injected silane treatment was determined by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The results indicated that the resistance to water absorption, sulfate diffusion and chloride diffusion were improved by the EOT of silane. The silane treatment had a limited impact on carbonation resistance. An impervious film with a dense structure was formed in the carbonated mortar through the EOT of silane, and this treatment did not introduce new crystal phases to the hydration products within the carbonated mortar.

Investigation of the time-dependent bearing capacities of concrete structures in different environments considering climate change

The escalating trend of emissions of greenhouse gases, including CO2, prompts significant modifications in climate variables, such as temperature and relative humidity (RH). For concrete civil infrastructures, the carbonation and chlorination corrosion processes are sensitive to changes in climate variables. The focus of this study is to evaluate the time-sensitive deterioration of concrete components in different corrosion environments with consideration of large uncertainties of climate change. Future projections for atmospheric CO2, temperature, and RH until the end of the twenty first century are examined. By implementing an aging corrosion model that incorporates climate change, the study observes that under the SSP5-8.5 emission scenario, the average carbonation depth for the RC structures in the general atmospheric environment increases by 58.7%. Furthermore, the chlorination corrosion rate in marine environments nearly doubles that under aging conditions alone. By 2100, corrosion-affected RC beams in the SSP5-8.5 scenario will lose 9.5 and 29.2% of their flexural capacity, respectively. Moreover, under carbonation and chlorination environments, the beams will face an additional loss of 20.7 and 27.6% in shear capacity, respectively. In performing the above calculations, we have considered the uncertainty prediction of climate change and the uncertainty analysis of the influence of model parameters and material variability.

Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).

Physical performance, durability, and carbon emissions of recycled cement concrete and fully recycled concrete

This study introduces innovative concepts for closed-loop recycling waste concrete to produce fully recycled concrete (FRC). Multiple test methods and characterization techniques were used to evaluate the physical properties and durability of four types of concrete (normal concrete, recycled aggregate concrete, recycled cement concrete and FRC). The fresh density, compressive strength, ultrasonic characteristics, chloride resistance, water adsorption properties, carbonation behaviors, and microstructure characteristics of these concretes were investigated. The water absorption behavior of FRC can be divided into three stages, with the initial stage having a water absorption rate three times that of ordinary concrete. It was found that carbonation depth varied among different concrete types, influenced by binder quality, which can affect the porosity and mechanical properties. Overall, recycled cement concrete and FRC demonstrate considerable potential for reducing carbon emissions, with total emissions of 59.152 kgCO2/m3, representing an 85 % reduction compared to ordinary concrete.

Performance and mechanism of carbon sequestration of air-entraining wet shotcrete

CO2 curing concrete technology refers to the CO2 reacts with cement clinker minerals to obtain high-performance concrete and achieve the purpose of energy saving and emission reduction. The researches of air entrainment agent (AEA) focus on the development of new AEA and the study of concrete performance after adding some AEA. In the background of CO2 curing concrete technology, there are relatively few researches on the influence mechanism of different characteristics of bubbles introduced by different AEAs on carbon fixation performance of concrete. This paper demonstrates the characteristics of air bubbles introduced by SY-5 AEA (main component: triterpene saponin) and LAS AEA (main component: sodium dodecylbenzene sulfonate), compares the strength of concrete mixed with above two types of AEAs cured for 28 days and analyzed them by carbonization depth test, ultrasonic detection of fissure test, SEM, XRD and TG. Results show that different AEAs introduced different characteristics of air bubbles, which affected the internal pore characteristics of concrete, and then affected its mechanical properties and carbon sequestration properties. Compared with SY-5 AEA, LAS AEA had a slightly lower air-entraining effect. But the bubbles introduced were even and stable, the internal pores of the hardened concrete were uniform. Although the former had a high carbon sequestration, the latter had a higher intensity at 28 d, about 2.69 % higher. Under carbonization curing conditions, the improvement of concrete properties was more evident when appropriate AEAs were incorporated. The compressive strength and the splitting strength were increased by 5.57 % and 4.5 % respectively under the carbonization curing condition.

Experimental analysis of mechanical properties of dredged sludge solidified by carbonized under the synergistic action of magnesium oxychloride cement and lime

The environmentally friendly magnesium oxychloride cement (denoted as MOC thereinafter) shows promising application prospects. Meanwhile, more emphasis is being paid to the environmental issues created by CO2 emissions. In this paper, carbonation-composite solidification technology is adopted to introduce MOC-lime cementitious material into sludge solidification. The effects of initial water content (H2O/MgCl2 molar ratio), lime content, MgO/MgCl2 molar ratio, and carbonation time on the mechanical properties and micro-mechanisms of sludge solidification were investigated using unconfined compressive strength (UCS), pH value, carbonation depth, mass loss rate, scanning electron microscopy (SEM), and X-ray diffraction (XRD) tests. The results show that the UCS of sludge solidification decreases with an increase in H2O/MgCl2 molar ratio, and increases first and then decreases with an increase in lime content, reaching a maximum value at H2O/MgCl2 molar ratio of 24.3 and lime content of 4 %. Notably, carbonation significantly improves the UCS of the samples, and with an increase in carbonation time, the mass loss rate and carbonation depth increase, while the pH value decreases. Additionally, uncarbonated samples show an increase in compressive strength with an increase in MgO/MgCl2 molar ratio, as the hydration products gradually transform from amorphous gel to crystalline phases 3, phases 5, and brucite (Mg(OH)2). Finally, XRD and SEM results indicate that the underlying mechanism for the significant improvement in strength and microstructure of the samples after carbonation is the formation of a block-like crystalline network with good binding ability, consisting of chlorartinite, nesquehonite, calcium carbonate, and C-S-H gel. This study promotes the use of MOC-based gel materials as a green stabilizer for sludge solidification, and the carbonation technique employed can improve the mechanical properties of solidified soil and significantly reduce the curing time.

Constitutive modeling and extended performance evaluation of concrete reinforced with non-hybrid waste tire steel fibers

This paper investigates the extended performance and constitutive modeling of waste tire steel fiber reinforced concrete (WFRC), making notable contributions to civil engineering materials. The study assesses constitutive modeling, reinforcement indices, and the long-term performance of concrete reinforced with varying percentages of waste tire steel fiber (WSF) ranging from 0.30 % to 1.75 %. A modified analytical model for predicting compressive stress-strain curves of WFRC is introduced and compared with previous analytical models for fiber-reinforced concrete. Additionally, a novel waste tire steel fiber reinforcing index, based on WSF properties, is proposed. Empirical relationships between strength properties and reinforcement indices are established. Experimental strength properties at the standard age, as well as water absorption, carbonation depth, and split-tensile strength of specimens aged beyond the standard age at 600 days and fiber-matrix interaction obtained by SEM analysis, are reported. Prediction models are proposed for estimating the mechanical properties of WFRC at the standard age, with results compared against existing codes. The proposed modified analytical model for the uniaxial compressive stress-strain curve demonstrates better coherence with experimental curves than existing models. Furthermore, empirical equations developed in terms of the waste tire steel fiber reinforcing index demonstrate satisfactory alignment between predicted and experimental strength properties. Significant improvements are observed in specimens aged 600 days, indicating the promising role of WSF in enhancing the long-term performance and serviceability of structures. Further studies are recommended to explore the performance of WFRC in aggressive environmental conditions.

Early age accelerated carbonation of cementitious materials surface in low CO2 concentration condition

Accelerated carbonation curing contributes to the carbon sequestration effect of cementitious materials and enhances surface density. However, in large-scale applications, traditional high CO2 concentration conditions (>5 % CO2) are constrained by economic costs. This study traces the early-stage accelerated carbonation process of cement mortar under low CO2 concentration (3 % CO2) condition from the perspectives of the evolution of CaCO3 crystal types, phase transformations, and microstructural changes, and compares the results with those under the 20 % CO2 condition. The results show that the carbonation depth of mortar specimens cured under the 3 % CO2 condition is shallower, but the cumulative concentration of CaCO3 within the surface 3 mm is not significantly lower than that under the 20 % CO2 condition; The carbonation zone generates more low-crystalline forms of CaCO3; The accelerated carbonation process does not affect the formation of CH and ettringite. Microscopic results indicate that under the 3 % CO2 condition, the synergistic effects of hydration and carbonation are better, and appropriately extending the curing time helps to refine the pore structure of the carbonation zone and improve the density of the substrate surface.

Corrosion resistance of polymer-modified hardened cement paste and phosphoric acid-activated metakaolin geopolymer in carbonic acid solution

Corrosion resistance of hardened Portland cement paste (HCP), polymer-modified hardened cement paste (PHCP) and phosphoric acid-activated metakaolin (PMK) geopolymers in carbonic acid solution was comparatively evaluated by multiple techniques of thermogravimetry (TG), energy dispersive spectrometer (EDS), fourier transform infrared spectrometer (FTIR), inductively coupled plasma optical spectrometer (ICP), microindentation and compressive tests. The incorporated polymer kinetically slows down the corrosion process of Portland cement paste as the carbonation depth of PHCP is lower than those of HCP characterized by all techniques. Meanwhile, the addition of polymer slightly hinders leaching of substances from HCP by blocking the pores. Despite the increase of elastic modulus, decreases of compressive strength of both HCP and PHCP samples caused by carbonation are observed probably due to the generation of microcracks and uneven brittleness across the section. PHCP presents less mechanical loss after carbonation treatment than HCP. PMK geopolymer samples soaked in deionized water and carbonic acid solution have comparatively identical results of TG, EDS, FTIR and mechanical measurements, indicating that the PMK geopolymer is highly resistant to carbonic acid, thanks to its inherent acidic nature. In addition, the leaching amount of PMK geopolymer in carbonic acid solution is also much less than the HCP and PHCP.

Effect of low carbon marble dust powder, silica fume, and rice husk ash as tertiary cementitious material on the mechanical properties and embodied carbon of concrete

The recent decade has seen a surge in study towards cost-effective, ecologically benign, as well as socially advantageous cement replacements. Alternatives include industrial and agricultural waste, which can be recycled, repurposed, as well as renewed. However, using these wastes as supplementary cementitious materials (SCM) saves energy as well as reduces cement use, which helps reduce CO2 emission. Therefore, this research investigation is to use the silica fume (SF), rice husk ash (RHA), as well as marble dust powder (MDP) individually as SCM and combine as tertiary cementitious materials (TCM) for determining the fresh (workability), hardened (dry density, splitting tensile and compressive strength) and durability (carbonation depth, and water absorption) properties of concrete. In this regard, 345 concrete samples were made with 1:1.5:3 mix ratio and cured for 28 days. The outcome has been demonstrated that the workability, dry density, water absorption and carbonation depth of concrete is getting reduced with growing the SF, RHA and MDP as SCM and TCM in concrete. Besides, the compressive and split tensile strength are increased by 10.44% and 9.544% respectively at 9% of SF, RHA and MDP as TCM for 28 days. Besides, the embodied carbon of concrete is decreasing while amount of SF, RHA and MDP as SCM and TCM is increasing. It has been observed that the use of 9% TCM is offering good results for construction sector and reduce the consumption of cement in concrete which helps to decrease the carbon emission in the environment.

Effect of High-Tenacity Polypropylene Fibers on the Carbonation Resistance of Expanded Polystyrene Concrete

Expanded polystyrene concrete (EPSC) is increasingly utilized in buildings as a green building material. To investigate the effect of high-tenacity polypropylene (HTPP) fibers on the carbonation resistance (CR) of EPSC, five groups of EPSC specimens with HTPP fiber volume fractions of 0%, 0.6%, 0.9%, 1.2%, and 1.5% were prepared. Rapid carbonation tests were conducted to measure the carbonation depth (CD) and uniaxial compression strength (UCS) of the specimens at different carbonation ages (3, 7, 14, and 28 days). The CD and UCS of the specimens were calculated and analyzed. The results indicated that the HTPP fibers dramatically improved the CR of EPSC, with a decrease in the CD of up to 29.5% at 28 days. A model for predicting the CD of EPSC was developed. The model for the strength after carbonation also showed good agreement with the experimental results. Scanning electron microscopy (SEM) was used to examine the microstructure of the HTPP-reinforced EPSC, while the mechanism of HTPP fibers to enhance the CR of EPSC was elucidated. The findings of this study provide valuable insights for the application of EPSC as a structural material.

Enhancing carbonation resistance of calcium sulfoaluminate belite-based concrete: comparative analysis and admixing strategies

Calcium sulfoaluminate belite (CSAB)-based cement exhibits useful properties such as low CO2 footprint, high early-age strength and shrinkage compensating behavior. Our previous study examined the mechanism of carbonation in CSAB-based binder and reported a higher degree of carbonation in CSAB-based binder compared to Portland cement (PC) binder. This study examines the admixing strategies to improve the carbonation resistance of CSAB-based binders. The addition of gypsum or calcium hydroxide reduced the carbonation depth (in natural and accelerated environments) in the CSAB binder. Gypsum addition reduced the pH and resulted in pore refinement. Whereas calcium hydroxide addition increased the pH and promoted the formation of monosulfate (AFm). Although the carbonation depth was reduced in the presence of gypsum or calcium hydroxide, the addition of calcium hydroxide offered a better admixing strategy due to its higher pH which is crucial for the passivation of reinforcement.

Evaluating carbonation resistance and microstructural behaviors of calcium sulfoaluminate cement concrete incorporating fly ash and limestone powder

This study investigates the effects of accelerated carbonation on calcium sulfoaluminate (CSA) cement concrete, focusing on mixtures enhanced with 20 % fly ash (FA), 20 % remediated fly ash (RF), 15 % limestone powder (LP), and a combination of 20 % FA with 15 % LP (35 %). The study further evaluates the mechanical properties including compressive strength, splitting tensile strength, elastic modulus, along with drying shrinkage and bulk resistivity. To delve into the microstructural characteristics of moist curing versus carbonation exposure on the CSA cement system, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were employed, particularly analyzing phase assemblage changes. The results show that the addition of FA reduced the carbonation depth in concrete mixtures over time (105 days). However, LP and the combination of FA and LP presented mixed effects. The microstructural analysis highlighted ettringite as the predominant phase in samples moist cured for 3 days. In contrast, carbonation-cured samples were characterized by different calcium carbonate (CaCO3) polymorphs alongside aluminum hydroxide (Al(OH)3) and residual ye'elimite, with the formation of low-pH carbonic acid facilitating the conversion of ettringite into CaCO3. This study highlights the impact of different SCMs on the durability and microstructural characteristics of CSA cement concrete, underscoring the interplay between curing methods, effects of SCM, and carbonation processes.

On determination of characteristic in-situ carbonation depth from existing concrete structures

In this study, the overall carbonation depth of existing bridges was investigated to establish practical guidelines for diagnosing structural carbonation. Carbonation depth was measured by obtaining cross-sections and core samples of girder-slabs from six existing concrete bridges scheduled for dismantling. The variation in carbonation depth based on the structures' location was analyzed. Moreover, various protocols were proposed for deriving the characteristic values of in-situ carbonation depth for concrete structures and each protocol was verified through probabilistic simulations. Carbonation depth exhibited inconsistency across the cross-section, varying significantly depending on the location, but a deeper carbonation was especially noticeable in locations subjected to bending or tensile stress by design. The method to select the largest value from the core data obtained are considered suitable to prevent both underestimation and overestimation.

Strength and Durability Studies on Concrete using Cashew Nut Shell Ash (CNSA) waste as Supplementary Materials

<p><span style="font-size:12pt"><span style="font-family:"Times New Roman","serif"">As the world population is expected to increase significantly, there is a greater need for housing and, as a result, building materials. Conventional manufacturing methods for materials such as concrete involve substantial energy usage and substantial release of carbon emissions, which contribute to environmental deterioration. This study investigates the incorporation of Cashew Nut Shell Ash (CNSA) as a partial replacement for Ordinary Portland Cement (OPC) as primary cement, while CNSA formed binary blends. The study examined various water-to-binder ratios (0.55, 0.50, and 0.45) and a total binder content of 310 kg/m³, with replacement levels at 0%, 10%, 20%, 30%, and 40%. Compressive strength tests were performed at 2, 7, 28, and 90 days, shows a consistent increase in strength over time. Optimal CNSA content (10-30%) enhanced long-term strength due to its pozzolanic activity. Additionally, the elastic modulus was tested, indicating improved stiffness in mixes containing CNSA in comparison with the conventional concrete systems. Durability tests such as Rapid Chloride Permeability Test and carbonation depth analysis showed that CNSA addition generally decreased chloride conductivity, thereby enhancing durability. However, replacement levels (beyond 40%) exhibited diminishing returns. The results suggest that CNSA is a viable partial replacement for cement, improving concrete's workability, density, and long-term strength while enhancing durability against chloride penetration and carbonation. These findings support CNSA's potential in creating sustainable and resilient concrete systems.</span></span></p>

Enhancement of Compressive Strength and Durability of Sulfate-Attacked Concrete

This experimental study is carried out in order to improve the properties of sulfate-attacked concrete. The concrete specimens were immersed in 15% Na2SO4 solution before being protected with a concrete repairing agent (CRA). The effects of sulfate corrosion time, the curing time after being attacked, and the concrete repairing agent on concrete were investigated. The experimental results indicate that the properties slightly increased after being attacked by sulfate for 60 days than for 30 days. However, they decreased after being attacked by sulfate for 90 days. CRA could effectively improve the properties of sulfate-attacked concrete. After being re-cured for 7 days, the properties of the sulfate-attacked concrete were significantly improved in comparison with those of the specimens taken out from the sulfate solution immediately. When the specimens were attacked for three months, the compressive strength of specimens coated with CRA was increased by 6.1%, 6.4%, and 6.4% compared to that of the specimens without CRA after being cured for 7 to 56 days, respectively. The carbonation depth of concrete specimens with CRA was reduced by 4.6%, 8.3%, and 4.9%, respectively. However, the chloride ion permeation coefficient of concrete with CRA decreased by 20.3%, 28.5%, and 28.7%, respectively, for the concrete immersed in sulfate for one month.

Magnetic susceptibility and properties of Alisols under forest and crops in south Amazonas

Anthropic actions have motivated pieces of research on the impacted naturally poor soils of the Brazilian Amazon, requiring the use of diagnostic attributes that are increasingly specific to each environmental change. The use of magnetic proxies inherent in the soil may be the key to understanding the changes that occur in the soil and the environment. Therefore, this study aimed to characterize the physical, chemical and mineralogical properties of Alisols, in addition to determining the intensity and origin of the magnetic signal for future calibrations as an environmental proxy for monitoring soil fertility. One natural and three cultivated Alisols were sampled using systematic meshes in three layers: 0–5, 5–10 and 10–20 cm. The natural Alisol is a tropical forest and the agricultural ones refer to the cultivation of annatto, cupuaçu and guarana. A total of 192 samples/area were submitted to physical, chemical, mineralogical and magnetic susceptibility (MS) analysis. MS measured at low and high frequency and converted to specific mass (χlf and χhf), then descriptive, univariate and multivariate statistical analyzes were applied to the results. The conversion of the physically good and chemically poor and acidic natural Alisols to agricultural crops, caused an increase in the density and amplitude of the pH in water and Al3+ of the soil, plus a reduction in macroporosity, gravimetric humidity, available phosphorus and iron oxalate contents, and the incorporation of organic carbon in depth. All Alisols showed low χlf and χhf. However, χlf values decreased in depth for cultivated Alisols (0.53–0.26 x 10−6 m3 kg−1), whereas, for natural Alisol, these values tended to increase towards the subsurface (0.21–0.23 x 10−6 m3 kg−1). Nevertheless, the value of χlf and χhf were highly representative within the cultivation areas, which was characterized as a suitable proxy to monitor the fertility of the Alisols in the Amazon region.

Study on phase change materials integration in concrete: Form-stable PCM and direct addition

As the economy continues to develop, building energy consumption rises, necessitating sustainable solutions. Concrete, a pivotal building material, assumes a vital role in this context. To address the challenge of escalating energy consumption and environmental impact, this study studied the integration of phase change materials (PCMs) into concrete by two methods. Recycled aggregates serve as form-stable mediums for PCM absorption, while direct addition methods incorporate 7.5 % and 15 % free liquid PCM by volume of river sand. Six concrete mixtures underwent comprehensive evaluation encompassing workability, density, water absorption by immersion, compressive strength, flexural strength, chloride ion penetration, freeze-thaw cycling tests, and carbonation. The results reveal a decrease in concrete density and mechanical properties with increasing PCM content. Nevertheless, notable enhancements in chloride ion penetration resistance, reaching up to 18.5 % with free PCM incorporation, and zero carbonation depth were observed. These results underscore the potential of PCM-concrete composites in harmonizing energy efficiency and structural integrity, offering a sustainable alternative to fossil fuel-based air conditioning systems and with great potential from the point of view of the durability of the structures.