Mechanical Compressive Strength Research Articles

The Effect of Freeze-thaw on Mechanical and Ultrasonic Properties of Hungarian Oolitic Stones

The freeze-thaw process is a weathering phenomenon that occurs in rocks and stones when water enters small cracks and pores within the stone. When the temperature drops below freezing, the water inside the rock expands as it freezes, exerting pressure on the rock from within. In this study the effect of freeze thaw on mechanical parameter uniaxial compression strength (UCS) and ultrasonic pulse velocity (UPV) of 47 oolitic samples were considered. At first, capillary absorption for cylindrical and prismatic oolitic samples were measured and then freeze-thaw experiment with 23 cycles were applied to the samples. UPV of samples before and after freeze-thaw was analysed by two ultrasonic devices including Geotron and Pundit. It was observed that freeze thaw decreases primary velocity (Vp) and secondary velocity (Vs) by around 20 and 7% respectively. However, average UCS of 1.6 MPa indicates strength decrease of samples, which represent negative effect of pore expansion due to freeze thaw on strength parameter of samples.

Bambusa balcooa bamboo-reinforced concrete beams: experimental and FEM investigation for energy-efficient pavement construction.

This study explores the viability of using Bambusa bambos, sourced from Madhya Pradesh, India, as a reinforcement material in continuously reinforced concrete pavement (CRCP) construction, aiming to assess its potential as a sustainable alternative to traditional steel reinforcement. The research encompasses a comprehensive evaluation of physical and mechanical properties, including tensile, compressive, and bending strengths, and a detailed microstructural analysis using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) of Bambusa bambos. The study involved finite element analyses that modeled bamboo-reinforced concrete (BRC) beams, exploring the impact of horizontal and vertical placements of bamboo strips on flexural behavior under bending loads. The analysis aided in observing compressive and tensile stresses generated in concrete and bamboo, with specific FEA results indicating that beams with vertically aligned bamboo strips in both the compression (compressive stress of 16.90MPa for beam B1) and tension zones (tensile stress of 7.22MPa for beam B1) withstand flexural stresses effectively. Additionally, the multi-criteria decision-making approach using the TOPSIS method to rank different beam designs. Key findings obtained from FEA indicate that the vertical alignment of bamboo strips in both the compression and tension zones of the beams is optimally effective in handling flexural stresses.

Evaluating the fresh and mechanical properties of steel slag aggregate concrete reinforced with steel fiber

In this study, steel slag (SS) and steel fiber (SF) were used to make environment-friendly high-strength concrete. Natural coarse aggregate (NCA) was initially substituted partially with SS at various substitution levels, i.e., 25 %, 50 %, 75 %, and 100 %, respectively, for getting the optimum substitution levels of SS in concrete. Afterward, SF, having an aspect ratio of 60, was considered with volume fractions of 0.15 %, 0.3 %,0.45 %, 0.6 %, 0.75 %, 0.90 %, 1.05 %, and 1.2 % in concrete. The water-to-binder ratio was taken as 0.35 for all the concrete mixes. For the fresh property, slump and compaction factor of concrete were determined. Similarly, for the mechanical property compressive strength (CS), split-tensile strength (STS), and flexural strength (FS) have been tested after the curing age of 28 and 56 days. Additionally ultrasonic pulse velocity (UPV) test was conducted to measure the quality of concrete. X-ray diffraction (XRD) was also performed to analyze crystalline phases and identify mineralogical composition within the concrete matrix. All the tests were compared with the standard concrete made with NCA. It has been found that the addition of steel slag aggregate (SSA) and SF enhances the mechanical properties of concrete, whereas it reduces workability. Substituting 50 % of SSA for NCA alongside 1.05 % of SF results in the highest CS, while employing 1.2 % SF achieves maximum STS, FS, and UPV.

Utilization of (Ca, Mg)-Zr phosphates adsorbents saturated by Cs+, Sr2+, Co2+ ions in NZP ceramic matrices

A novel approach to the utilization of (Ca, Mg)-Zr phosphate adsorbents saturated by Cs+, Sr2+, Co2+ ions was developed. The main stages include: (i) Cs+, Sr2+, Co2+ ions adsorption, (ii) the drying and shaping by cold pressing, (iii) the sintering. Metal ions leaching from the powder of the spent adsorbent were 0.2-26.5% in distillation water (рН 4.0-10.0) and tap water, and increased to 6.4-68.2% in seawater. Calcination of spent adsorbents at 1000 °C led to a decrease in Cs+, Sr2+, Co2+ ions leaching to less than 1.0% in tap and seawater. The ceramic matrices with a Cs+, Sr2+, Co2+ content of 8.0-30.2wt.%, mechanical compressive strength of 2.9-260.9MPa, leaching rate of 1.0×10-4 - 4.3×10-7g/(cm2×day), density of 1.4-3.4g/cm3 were obtained by cold pressing with subsequent sintering. The samples obtained at molar ratios Zr/(Ca+Mg) of 0.35 and 0.21 were characterized by the highest compressive strength and Cs+ and Sr2+, Co2+ leaching resistance, respectively. The obtained ceramic matrices fitted to the requirements of GOST R 50926-96 and NRC 1991 for solid high-level waste forms.

Synthesis and biophysical characterization of porous bi-phase calcium phosphate/gelatin-PVA scaffold: Enhanced antibacterial, osteoconductivity and anticancer activity via silver nanoparticles and methotrexate incorporation

In our relentless pursuit of advancing bone tissue regeneration, we have meticulously crafted multifunctional scaffolds that transcend traditional approaches. These freeze-dried scaffolds, composed of biphasic calcium phosphate (BCP) intricately woven into a gelatin-polyvinyl alcohol (PVA) matrix, harbor the potential to revolutionize regenerative medicine. The scaffolds are characterized with XRD, FTIR, SEM, 3D images of the SEM, mechanical properties, swelling and degradation tests, drug release, cell viability, antibacterial and anticancer tests. Our in-situ synthesis of BCP within the PVA framework yielded a biphasic structure comprising hydroxyapatite (HAp) and beta-tricalcium phosphate. These scaffolds exhibit good mechanical compressive strength (ranging from 28 to 173 kPa) and boast high porosity levels (approaching 80 %) enhance the processes of nutrition and waste removal. The incorporation of silver nanoparticles (Ag) introduces antimicrobial prowess, resulting in a complex scaffold texture characterized by well-defined pores and rugged walls. The interconnectivity within this fibrous network contributes to enhanced mechanical properties. Additionally, our scaffolds facilitate the sustained release of methotrexate (MTX), a potent anticancer agent. Within the first day, MTX is promptly delivered, potentially impacting cancer cells. These Ag-containing scaffolds effectively combat common pathogens, demonstrating significant antibacterial activity as an essential property for preventing infections at the implantation site. Notably, our scaffolds, whether infused with Ag or MTX (at a concentration of 0.25 wt%), exhibit no toxic effects on Vero and MG-63 cells within a 24-hour window. However, higher Ag content (2.0 wt%) shows cytotoxicity. In summary, our multifaceted scaffolds, poised at the intersection of science and creativity, hold immense promise for bone tissue engineering. Further investigations will explore long-term effects, broader microbial contexts, and in vivo models.

Mechanical characterization and strain analysis applied to the heat treatment of wood materials, by means of digital image correlation

Digital image correlation (DIC) was used to examine the strain distribution of heat-treated beech and Uludag fir woods in mechanical testing. It also evaluated the effects of the heat treatment process on the properties of the wood samples. The physical (mass/density loss, dimensional stability, color change, and surface roughness), mechanical (flexure test and compressive strength), morphological, thermal, and structural properties of the heat-treated wood were examined. It was determined that the heat treatment parameters can be optimized using the DIC method. The test results showed that although heat treatment can provide improved physical and thermal properties, it caused micro-crack formations and collapses in the wood cells. As a consequence, the mechanical properties of the heat-treated wood materials decreased with the heat treatment process. There were slight differences in the curves of the samples according to Fourier infrared and X-ray diffraction analyses. Morphological characterization showed that the heat treatment triggered large cracks in the cell wall and lumens and the morphological structure of heat-treated wood was affected at large percentages.

Poly (glycerol sebacate) – co – 2 – hydroxyethyl methacrylate bioelastomeric nanohydroxyapatite composites: Mechanical properties, thermal characteristics, and cytocompatibility studies

AbstractIn this study bioelastomeric co‐polymer comprised of glycerol, sebacic acid, and 2‐hydroxyethyl methacrylate, loaded with varied contents of nanohydroxyapatite (0%–8%) has been synthesized via polycondensation reaction. The mechanical properties, that is, tensile and compressive strength and modulus have been enhanced due to the addition of silane‐treated nanohydroxyapatite. The optimal mechanical properties for these nanocomposites have been found to be at 7% nanohydroxyapatite loading. X‐Ray diffraction analysis and scanning electron microscopy (SEM) revealed efficient dispersion of nanohydroxyapatite throughout the matrix as particles and as well as agglomerates. The synthesized composite was found to be cytocompatible and showed excellent biocompatibility by forming thick apatite layers in simulated body fluid.Highlights Synthesis of PGS/nHA bioelastomeric nanocomposite via polycondensation. Characterization of nanocomposite with FTIR, TGA, XRD, SEM, AFM. Water absorption, bioactivity and cytocompatibility assessment. In vitro degradation evaluation.

Geotechnical Model Testing with High-Strength Gypsum Similar Materials: A Case Study on Quartzite-Like Formulations

This paper explores the formulation and optimization of high-strength gypsum-based similar materials for geomechanical model tests, with a specific focus on their application in simulating conditions analogous to quartzite. Employing an orthogonal experimental design, key factors such as quartz sand-to-gypsum ratio, cement-to-gypsum ratio, and barite content were systematically varied. Through a series of indoor experiments, comprehensive assessments of physical and mechanical properties, including density and compressive strength, were conducted for diverse material ratios. The results reveal a broad spectrum of physical and mechanical indicators, aligning with the requisites for model tests across varying similarity ratios. Notably, a high-strength gypsum formulation yielding a uniaxial compressive strength within the precise range of 10~20 MPa was identified, providing valuable insights for researchers engaged in hard rock model tests using similar materials. The study underscores the influential roles of barite content, quartz sand-to-gypsum ratio, and cement-to-gypsum ratio on the density and compressive strength of similar materials. This research contributes essential data for the application of high-strength gypsum in geotechnical model testing, particularly in replicating the mechanical behavior of quartzite.

Effect of straw fibers addition on hygrothermal and mechanical properties of carbon-free adobe bricks: From material to building scale in a semi-arid climate

To achieve net-zero carbon emissions in a building's lifecycle, a comprehensive approach is required, addressing both embodied and operational carbon footprints. To support this goal, this study assesses the environmental, hygrothermal, and mechanical characteristics of different carbon-free adobe bricks bio-sourced with straw and evaluates their impacts on improving the energy performance of a one-story case study building located in a semi-arid climate. At the material scale, the mechanical performance, hydrothermal behavior, and durability of carbon-free straw-reinforced adobes, with weight percentages of 0, 1, 2, 3, and 4%, at different sizes: long straw (100–200 mm) and crushed straw (5–25 mm) were studied. The results show that incorporating straw into bricks increases porosity, enabling the production of lightweight bricks that comply with Moroccan standards for lightweight structures, possessing a density lower than the accepted limit of 1750 kg/m³. Furthermore, the thermomechanical properties of reinforced adobes were considerably improved compared to non-reinforced ones, with a gain in mechanical compressive and flexural strengths of 31.2% and 184%, respectively. However, it is important to note that in the case of adobe bricks reinforced with long straw (BLS), the findings revealed that, unlike other thermomechanical properties, long straw has a negative effect on compressive strength. Additionally, thermal conductivity decreased by 93.8% and 86.8% for a 4% inclusion of long and crushed straw, respectively. At the building scale, the indoor hygrothermal comfort was evaluated with respect the hot, semi-arid region in southern Morocco. The results show that the reinforced adobe material is able to reduce the indoor temperature of the case study building from 3 °C to 12 °C during the summer time, compared to the outdoor temperature, with a time lag of up to 5 h between the interior and exterior. Moreover, it successfully maintained diurnal indoor air temperature fluctuation within 2 °C. In addition, indoor relative humidity remained in the recommended 40%–65% by ASHRAE Standard 62.1–2022, over 78% during the monitoring period, even when the outside relative humidity fluctuated significantly (5–95%). Finally, a Morris-based sensitivity analysis was carried out on nine design parameters of the case-study building to assess the impact of varying the thermal properties of reinforced adobe bricks on cooling and heating energy performance, respectively. Thermal conductivity was found to have a significant impact on cooling energy demands and a lesser influence on heating demands. The study also indicates that straw-reinforced adobe bricks can improve cooling energy performance by up to 17.8% without compromising the overall embodied carbon of the building envelope.

Influence of zinc-containing compounds on the properties of ceramic materials based on the Li<sub>2</sub>O–MgO–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> system

The results of a study the influence of magnesium oxide substitution with zinc oxide in the Li2O–MgO– Al2O3–SiO2 system, as well as the introduction of pre-synthesized ganite ZnAl2O4, on sintering, phase formation and thermal expansion of synthesized materials are presented. It was found that after substitution of 4 % magnesium oxide MgO with zinc oxide ZnO, the ceramic material synthesized at a temperature of 1 150 °C was characterized by higher values of apparent density (not less than 1 835 kg/m3), mechanical compressive strength (300 MPa), and heat resistance (more than 80 thermal cycles), as well as low values of LTEC (–0,25 ∙ 10–6 K–1), which is due to the formation of crystalline phases of spodumene, spinel, forsterite, corundum, ganite and quartz.

Study of the influence of warehousing conditions on the aging durability of bamboo

Bamboo photoaging refers to the chemical and physical changes in the surface after sunlight during outdoor/indoor use, such as texture roughness, polymer molecular chain fracture, and chemical structure changes. The study of bamboo aging during storage is an important part of the industrialization of bamboo as a substitute for plastic initiative. Photoaging during bamboo warehousing and its use is an important factor affecting performance and the use of the final product. To better evaluate the aging response mechanism caused by ambient light during bamboo warehousing, four aging conditions including ultraviolet light aging (UV-aging), indoor-light/light-avoidance cycle (Control), light avoidance (Avoid-light), and 90% RH (Avoid-light 90%) were simulated. The dimensional stability, mass, density, morphology, compressive mechanical strength, and other properties were monitored periodically according to 0, 7, 14, 28, 56, and 180 d. The change mechanism of bamboo under photoaging conditions was analyzed using SEM, FTIR, XRD, and TG. The synergistic effect of different factors under photoaging conditions was studied by redundancy analysis, and different photoaging environment prediction models were established using the long- and short-term memory (LTSM) model. The results showed that during the warehousing cycle of 180 d, the damage of light intensity to bamboo exposure was greater than that of the avoid-light treatment group, the humidity factor was negatively correlated with mechanical properties, the light factor was highly negatively correlated with dimensional stability, and the 30%–60% RH avoid-light condition showed excellent durability. The predictability of photoaging performance evaluation in a warehousing environment has important reference value for industry.

Evaluation of the technical properties of reactive-MgO cements produced by solar calcination of magnesite in a fluidized bed reactor

Magnesium oxide (MgO)-based cements display very interesting technical properties and environmentally-friendly features. The novel idea investigated in this study is to synthesize MgO cements, using as raw material natural magnesite calcined in fluidized bed heated by concentrated solar energy. Calcination was performed in a lab-scale system equipped with a concentrated solar simulator, operated under different process conditions. The most reactive MgO was mixed with 3% by weight of MgCO3 (nucleation agent) and four different solutions containing magnesium acetate or chloride. The binders were hydrated in air or 20% CO2 atmosphere (accelerated carbonation conditions) until 28 days. X-ray diffraction, differential-thermal and mercury intrusion porosimetry analyses, and compressive mechanical strength tests, were performed on the hydrated systems. Solar calcination produced a highly reactive MgO. The performance of the cement pastes improved at higher curing times, and when using magnesium acetate as hydration agent, as also witnessed by the application of a kinetic model. Accelerated carbonation conditions further enhanced the mechanical properties of the cements thanks to the formation of nesquehonite, allowing to reach a mechanical strength comparable to that of ordinary Portland cements class 32.5. The achieved outcomes encourage the production of low-CO2 magnesite cements from solar calcined magnesite, boosting the green aspect of the entire process.

Geopolymerization of Recycled Glass Waste: A Sustainable Solution for a Lightweight and Fire-Resistant Material

Glass is considered a sustainable material with achievable recovery rates within the EU. However, there are limited data available for construction glass waste management. Furthermore, glass is a heavy material, and considering the geographical limitations of Cyprus, the transportation trading cost within the EU is extremely high. Therefore, another method for utilizing this by-product should be developed. The aim of this research is to investigate the production of a low-cost, lightweight and fireproof material able to retain its structural integrity, using the geopolymerization method with the incorporation of randomly collected construction glass waste. The glass waste was initially processed in a Los Angeles abrasion machine and then through a Micro-Deval apparatus in order to be converted to a fine powder. Mechanical (compressive and flexural strength), physical (setting time and water absorption) and thermal properties (thermal conductivity) were investigated. The fire-resistant materials presented densities averaging 450 kg/m3 with a range of compressive strengths of 0.5 to 3 MPa. Additionally, a techno-economic analysis was conducted to evaluate the viability of the adopted material. Based on the results, the final geopolymer product has the potential to be utilized as a fire resistance material, preventing yielding or spalling.

Stiffness enhancement of polymer nanocomposites via graphene nanoplatelet orientation

AbstractIn the development of National Aeronautics and Space Administration (NASA)'s Unmanned Aerial Vehicles (UAVs), lightweight and durable materials play a crucial role for extended high‐altitude flights. Nanoparticle‐reinforced polymer composites meet these requirements, exhibiting resistance to environmental degradation. Despite their potential, the outstanding specific strength, corrosion resistance, and dimensional stability at elevated temperatures of graphene–epoxy nanocomposites have not been fully realized due to inadequate dispersion and spatial orientation within epoxy matrices. Our recent research has introduced a mathematical framework aimed at optimizing alignment parameters for graphene nanoplatelets (GNPs) and Fe3O4‐attached GNP under a weak DC magnetic field. Subsequently, nanocomposites reinforced with GNP and aligned Fe3O4–GNP nanoparticles were fabricated using optimized parameters, and their alignment was characterized using various techniques. The current study examines the influence and comparative impact of alignment and weight percentage (wt%) loading of both nanoparticles on various mechanical properties, including tensile and compressive strength, along with failure mechanisms. It was observed that both GNP and aligned Fe3O4–GNP enhance the mechanical properties of nanocomposites, particularly notable improvements from aligned Fe3O4–GNP. The Young's modulus of GNP nanocomposites increased by 17%, while aligned Fe3O4–GNP contributed significantly to a 31% enhancement in the Young modulus.Highlights Epoxy nanocomposites featuring well‐dispersed GNP and Fe3O4–GNP nanoparticles. Proper alignment of Fe3O4–GNP within the epoxy nanocomposite was achieved. Mechanical properties improved with GNP and aligned Fe3O4–GNP incorporation. The aligned Fe3O4–GNP exhibits advanced potential for engineering applications.

Fabrication and investigation of a pentamerous composite based on calix[4]arene functionalized graphene oxide grafted with silk fibroin, cobalt ferrite, and alginate

This paper presents a new scaffold made from graphene oxide nanosheets, calix[4]arene supramolecules, silk fibroin proteins, cobalt ferrite nanoparticles, and alginate hydrogel (GO-CX[4]/SF/CoFe2O4/Alg). After preparing the composite, we conducted various analyses to examine its structure. These analyses included FTIR, XRD, SEM, EDS, VSM, DLS, and zeta potential tests. Additionally, we performed tests to evaluate the swelling ratio, rheological properties, and compressive mechanical strength of the material. The biological capability of the composite was tested through biocompatiblity, anticancer, hemolysis, antibacterial anti-biofilm assays. Besides, the rheological properties and swelling behaviour of the composite were studied. The results showed that the scaffold is biocompatible with Hu02 cells and the cell viability percentages of 85.23 %, 82.78 %, and 80.18 % for were acquired for 24, 48, and 72 h, respectively. In contrast, the cell viability percentage of BT549 cancer cells were obtained 65.79 %, 60.45 % and 58.16 % for same period which confirmed notable anticancer activity of the product composite. Moreover, a significant antibacterial growth inhibition against E. coli and S. aureus species highlights its potential as an effective antibacterial agent. Furthermore, the observed minimal hemolytic effect (6.56 %) and strong inhibition of P. aeruginosa biofilm formation with a low OD value (0.24) indicate notable hemocompatibility and antibacterial activity.

Variation in the Composition Properties and its Effect on the Mechanical Properties of a cortical bone

Cortical bone is a composite material with varying mechanical properties as per the anatomical locations, orientations, etc. The relationship between bone cortical composition properties and compressive mechanical strength is important for selecting the right scaffold material. The findings show that the mineral content consisting mainly of hydroxyapatite crystals has a positive effect on the mechanical properties of the cortical bone, that is, an increase in the mineral content can increase the load capacity of the scaffold. According to this study, wet and dry densities equally impact the compressive strength and modulus of cortical bone. In addition, the presence of water degrades the quality of bone and reduces its ability to function, the variation in composition and its effect on mechanical properties must be considered when creating Scaffolds. The findings highlight the need to consider the properties of these composites when selecting scaffold materials for tissue engineering. The results of this study may help create biomimetic scaffolds with enhanced properties that support tissue regeneration and integration.

Experimental Analysis of the Mechanical and Machining Properties of an Aluminium Hybrid Metal Matrix Composite

In the current research, titanium carbide (TiC) is used to reinforce the aluminium alloy (AA 6063) in stir-cast hybrid composites at concentrations of 5, 10, and 15 weight percent together with 3 weight percent of graphite. The application of this developed composite is mainly used for automobile suspension parts. The portrayal of characters was performed, and the mechanical properties of the fabricated samples were investigated. Composites with different TiC weight percentages have their mechanical properties, including hardness, tensile strength, compressive strength, and flexural strength, measured and assessed. The results are shows that AA 6063 alloy with 3 wt. percentage of graphite with an increasing weight percentage of TiC composites are better in the mechanical property. The hardness of the AA 6063 alloy composites is greater than that of the base matrix alloy. The tensile strength of Al 6063 alloy composites has been reported to grow with increasing TiC particle content and to be significantly higher than the strength of the matrix alloy. Also, the SEM microstructure images clearly shows that 15 weight percentage of TiC with 3 weight percentage of Graphite shows the maximum distribution in the matrix.

Characterization of coating mortars from the warehouse of the former rheingantz factory in the Rio Grande, southern Brazil

The Rheingantz complex, dating from the 19th century, is composed of several elements, such as the factory, daycare center, and workers' house, and is located in the Rio Grande in Rio Grande do Sul, Southern Brazil. Currently, part of the complex is in the process of restoration. From this point of view, the great importance of the buildings for the conservation of the memory and cultural identity of the city and state suggests the study, of the historical mortars, in a pavilion, a former warehouse of the complex, lent to the Federal University of Rio Grande-FURG. The present paper aims to characterize the historical mortars of the pavilion's external coating. To identify the primary constituent materials, the mortars were characterized using tests suggested in the bibliography, such as X-ray diffraction (XRD), mechanical compressive strength, and water absorption. The characterization of the mortar samples showed that they are mainly composed of calcite and quartz, in a 1:5 ratio (binder: aggregate), and also have a significant presence of dolomite, which is indicative of a mortar substantially formed by dolomitic lime and sand. The results provided subsidies for the formulation of mortar suitable for restoration with characteristics similar to the original, providing mechanisms to reduce future pathological manifestations.

Bentonite Clays from Southeastern Spain as Sustainable Natural Materials for the Improvement of Cements, Mortars and Concretes

The effects of global climate change are becoming more evident and accelerating at an unprecedented pace. For this reason, human activities urgently need a paradigm shift to stop this entropic process before the consequences become irreversible. In this sense, the use of highly eco-efficient materials aimed at conveniently neutralizing CO2 greenhouse gas emissions entering into the atmosphere can contribute significantly to mitigating and reversing this process. This work aims to demonstrate the positive effects obtained when Portland cement is partially replaced by bentonite clays of volcano-sedimentary origin. The samples were initially characterized by various methods, such as Thin-Section Petrographic Study (TSP) and the analysis of mineral phases with XRD, chemical composition was determined via XRF, and morphological analysis was determined via scanning electron microscopy (SEM). To determine the technical properties of the samples, a qualitative chemical analysis (QCA) was performed, as well as a chemical analysis of pozzolanicity (CAP) at 8 and 15 days, respectively, and a study of the mechanical compressive strengths at 2, 7, 28 and 90 days. Characterization studies using TSP, DRX, FRX and SEM established that these bentonite clays have a complex mineralogical variety, composed mainly of smectite, mordenite, plagioclase and biotite, as well as altered volcanic glass and sericite. The results of the qualitative chemical analysis establish that more than 93% of the SiO2 present in the samples is reactive. Chemical analysis of pozzolanicity (CAP) showed significant pozzolanic behavior in all samples analyzed at both 8 and 15 days, while mechanical tests highlighted significant increases in mechanical strengths, with maximum values varying between 52.2 and 70.6 MPa at 90 days. These results show that the materials can be used as quality pozzolans for the manufacture of cements, mortars and concretes, which could be considered as a favorable factor and, therefore, relevant in the management and control of greenhouse gas emissions responsible for the deterioration of the environment.

Reviewing the Potential of Phase Change Materials in Concrete Pavements for Anti-Freezing Capabilities and Urban Heat Island Mitigation

This study provides an overview of how phase change materials (PCMs) can improve the resistance of concrete pavement to freeze–thaw cycles and mitigate the urban heat island (UHI) effect. The investigation covers different types of PCMs and methods for integrating them into concrete pavement, as well as the mechanical properties and compressive strength of concrete pavement when employing various PCMs. Prior studies have identified porous aggregates, microencapsulation, and pipelines containing liquid PCM as common approaches for PCM integration. Researchers have observed that the utilization of PCMs in concrete pavement yields favorable thermal properties, suggesting the potential for anti-freezing and UHI mitigation applications. However, the choice of PCM materials should be informed by local climate conditions.