Mortar Mixtures Research Articles

Viabilidade do Uso de Pó de Pedra em Argamassas como Substituto de Areia Natural

This article demonstrates the technical feasibility of replacing natural sand with stone dust in mortar mixtures. Laboratory tests were conducted to characterize sand and stone dust samples, an industrial by-product originating from quarries. Using a 1:8 ratio and a water/cement ratio of 0.5, according to ABNT NBR 13.276, the materials were used for mortar mixtures for bricklaying and coating. Cylindrical specimens were molded and stored in a humid chamber for different curing periods (7, 14, and 28 days). Compression tests and verification of the elastic modulus were conducted following ABNT NBR 7.215 recommendations. Additionally, experimental panels were built and coated with mortar mixtures dosed with sand and stone dust. Tensile strength tests on the coating were conducted on these panels. The results indicated that stone dust can replace natural sand in mortar mixtures for bricklaying and coating. In all curing periods studied, the specimens with stone dust showed performance equivalent to those dosed with natural sand. The elastic modulus also showed statistically similar values in both mixtures. Therefore, using stone dust to replace natural sand offers the construction industry a sustainable alternative, reducing environmental impact by utilizing quarry by-products instead of non-renewable natural materials.

The physical and mechanical consequences of incorporating industrial residues into mortar and concrete mixtures for eco-friendly marine constructions

The physical and mechanical consequences of incorporating industrial residues into mortar and concrete mixtures for eco-friendly marine constructions

Experimental study on flexural fatigue resistance of fiber-reinforced sustainable walnut shell ash mortar

In recent research on building materials, researchers have increasingly focused on replacing cement with agricultural waste. This approach offers significant advantages in terms of reducing global CO2 emissions and promoting the sustainability of building materials. In this paper, the use of the agricultural waste walnut shell ash (WSA) to partially replace cement in sustainable green mortars is explored. Specifically, equal amounts of WSA (5%, 10% and 15%) were used to replace cement. To offset the reduction in strength caused by the partial replacement of cement with WSA, basalt fibers were added to the mortar mixture. The effect of these fibers on the mechanical properties of the WSA-reinforced mortar was examined in compression tests, split tensile tests, and flexural fatigue cycle tests. In the flexural fatigue tests, the parameter and length of basalt fibers were varied and different stress levels (0.85, 0.8 and 0.75) were applied. The fatigue equations were developed using the Weibull model and p–s–n curves with a survival probability of 0.5 were derived. The results showed that the compressive strength and split tensile strength of the specimens increased with the addition of basalt fibers, with maximum values of 34.7 MPa and 3.8 MPa, respectively, and maximum increases of 8.78% and 21.95%, respectively. In addition, the average fatigue life of WSA mortar was 247,541 cycles, which increased by 139.26% when the stress level was 0.75, fiber length was 9 mm, and dosage was 0.3%. The linear regression fitting showed good correlation and provided valuable insights for practical engineering applications.

Preparation and characterization of core-shell structured CaCO3-SiO2 and hollow silica nanoparticles and evaluation of their effects on cement mortar properties

CaCO3-SiO2 particles having a core-shell nanostructure were produced by a modified Stöber process using CTAB as a surfactant. Then, a porous structure composed of a silica shell was formed after the removal of the CaCO3 cores as templates from the nanocomposite. To evaluate phase constitutions and microstructures of prepared nanoparticles, XRD, TEM, and FESEM–EDX techniques were utilized. The main aim of this work was to examine the usability of prepared CaCO3-SiO2 and SiO2 hollow shell nanoparticles instead of OPC in structural applications. In this way, the mixtures of cement mortar were made by partial replacement of 1% of cement mass with prepared nanoparticles. The amounts of calcium hydroxide (CH), bound water, and calcium carbonate for the prepared mortars have been calculated after 7 and 28 days of hydration through thermal analysis of TG/DTG. The results indicated that the CH content decreased by adding prepared nanoparticles as a cement replacement. As CaCO3-SiO2 and hollow SiO2 nanoparticles were used, the compressive strengths of mortars were enhanced by 34 and 59%, respectively, after 28 days, which were higher than the increasing influences on flexural strengths (29 and 55%). The increasing intensity of the XRD peaks related to the C-S-H phases and the decline of the orientation index of CH in a mortar containing silica shell suggest that hydration was further completed, leading to a strength improvement. The SEM micrographs indicated that the addition of prepared nanostructures improved the interface properties inside mortar and caused the microstructure to be denser.

LC3 cementitious binder incorporating microencapsulated phase change materials for self-defrosting traffic surfaces

Exposed surfaces of bridge decks, viaducts and pavements incur ice formation and accumulation of snow in cold seasons, which threatens traffic safety. Mitigating this problem using traditional methods such as deicing salts have caused ecosystem damage and inflicted substantial reinforcement corrosion and surface scaling to bridge decks and pavements, thus compromising their service life and causing colossal economic loss. This paper presents an alternative solution to overcome this problem through the development of a sustainable LC3 cementitious material incorporating micro-encapsulated phase change material (MEPCM) with low phase transition temperature to delay the surface temperature drop and mitigate snow accumulation and ice formation. MEPCM was incorporated in the cementitious matrix at 0 %, 10 % and 20 % by binder mass. Paste and mortar mixtures were prepared to investigate the microstructural, mechanical, physical, and thermal properties. Test results showed that incorporating MEPCM in the LC3 matrix achieved adequate compressive strength. Thermal simulations and visual observations conducted on mortar samples in the laboratory and outdoor exposure showed that MEPCM can effectively regulate the surface temperature of the LC3 matrix and mitigate temperature drops as well as snow accumulation. Analysis of temperature data in the 2023–2024 winter season of Hamilton, Ontario, Canada indicated that the MEPCM incorporated in mortar samples could effectively regulate 40 % of the total days considered and mitigate surface ice formation and snow accumulation, which provides both economic and environmental benefits.

Influence of graphene nanoplatelets on the passivation and corrosion resistance of carbon steel bars in ordinary portland cement mortar

This study investigates the influence of adding graphene nanoplatelets (GNPs) to mortar mixtures on the corrosion behavior of embedded carbon steel rebars. Mortar mixtures were prepared with a water-to-cement ratio of 0.42 and GNP replacement levels of 0, 0.05, and 1 percent by weight of cement. After 28 days of curing in an environmental chamber, the passivity and kinetics of chloride induced corrosion initiation for the rebars were studied using a suite of electrochemical tests. The results suggest that incorporating GNPs at low concentrations may enhance the passivity and resistance to chloride-induced corrosion of carbon steel rebars; however, due to the large variability in the data, the findings are inconclusive. Potentiodynamic measurements revealed that the estimated average polarization resistance of steel rebars in 0 G (no GNP), 0.05 G, and 1 G specimens in the passive state was on average −182.3, −276.5, and −304.2 kΩ, respectively. Upon exposure to chloride solution, 0 G specimens, with an average corrosion potential of −600 mV vs. SCE, exhibited the lowest resistance, whereas 0.05 G specimens, with an average of −491 mV vs. SCE, showed the highest corrosion resistance. Results from electrical impedance spectroscopy were consistent with the potentiodynamic findings. Surface characterization also revealed that the inclusion of GNPs does not alter the surface roughness of the interface between steel rebar and paste. However, the interface between rebar ribs and mortar paste had higher surface roughness and porosity in all specimens regardless of GNPs replacement level. Visual inspections confirmed that the area around the rebar ribs at the interface is more conducive to the formation of crevice and pitting corrosion.

Dense ceramics by cold reaction sintering using 95 % powdered construction and demolition waste and sodium silicate

This work explores the feasibility of producing ceramic-like materials from recycled construction and demolition waste through cold reaction sintering using sodium silicate as the liquid medium. The recycled material consists of a mixture of ceramics, mortar, and/or plasterboard - common building materials. Samples containing 95 wt% of recycled content were successfully fabricated at 150 ºC, a considerably lower temperature compared to conventional ceramic processes. These samples exhibited dense microstructures with relative densities of ∼ 90 %, as well as promising mechanical properties, including Vickers hardness values comparable to conventional bricks. In particular, samples with 30 % non-ceramic material showed more than twice the hardness when mortar was incorporated. Leaching tests confirmed the chemical stability of the material, with the incorporation of Ca²⁺ ions into non-leachable species, suggesting a reaction during CRS that enhances its durability. Additionally, FTIR analysis showed a blueshift in the signature from 973 cm⁻¹ to 1041 cm⁻¹ under more aggressive conditions, indicating structural changes and improved leachability. The primary advantage of this process would lie in the high recycled content used to create materials. This proposed new method allows obtaining dense pieces at very low temperatures, which also supposes a reduction of energy consumption, and therefore, an improvement of the sustainability of the production process. Given that this construction and demolition waste are often limited to not high added values, this approach not only supports environmental sustainability and resource conservation but also offers a viable pathway to decarbonizing the ceramic industry.

Development of Biodegradable and Recyclable FRLM Composites Incorporating Cork Aggregates for Sustainable Construction Practices.

Reducing energy consumption in the building sector has driven the search for more sustainable construction methods. This study explores the potential of cork-modified mortars reinforced with basalt fabric, focusing on optimizing both mechanical and hygroscopic properties. Six mortar mixtures were produced using a breathable structural mortar made from pure natural hydraulic lime, incorporating varying percentages (0-3%) of cork granules (Quercus suber) as lightweight aggregates. Micro-computed tomography was first used to assess the homogeneity of the mixtures, followed by flow tests to evaluate workability. The mixtures were then tested for water absorption, compressive strength, and adhesion to tuff and clay brick surfaces. Adhesion was measured through pull-off tests, to evaluate internal bonding strength. Additionally, this study examined the relationship between surface roughness and bond strength in FRLM composites, revealing that rougher surfaces significantly improved adhesion to clay and tuff bricks. These findings suggest that cork-reinforced mortars offer promising potential for sustainable construction, achieving improved hygroscopic performance, sufficient mechanical strength, internal bonding, and optimized surface adhesion.

Studying of Mechanical Behavior of Waste Materials Modified Cement Mortar

Large-scale environmental problems have been triggered by ceramic tiles from demolished buildings and animal bone waste. Therefore, optimizing their potential for reuse and recycling is an important goal of sustainable solid waste management. The primary objective of this study is to evaluate the feasibility of partial replacement of the fine aggregates in cement mortar with a combination of natural animal bone powder and industrial waste materials which is wall tiles ceramic powder. This study measures thermal and mechanical characteristics. Recycling construction waste is one of many ways to deny waste material from entering landfills and create new eco-friendly material that reduces energy consumption in buildings. Modified mortar cement specimens with 5% up to 25% mixtures were combined using a 1:3 ratio and a 0.5 W/C ratio to see how the ratios would affect the material’s properties. The addition of a superplasticizer boosted the cement mortar’s workability and compressive strength. The compressive strength, flexural strength, density, and thermal conductivity were evaluated for each mortar mixture ratio. Results showed that compared to regular cement mortar, cement mortar combined with 20% bone and ceramic powder wastes reached the optimal replacement percentage. Compressive strength increased by 54% and flexural strength by about 67%. At the 28-day mark, thermal insulation was lowered by 25%.It is concluded from this study that it is possible to use bone waste as a natural material with ceramic waste as an industrial material to modify the insulation and mechanical properties of cement mortar.

Effect of particle size distribution and content of limestone powder on compressive response of high-early-strength cement mortars

This study examined the effect of particle size distribution and content of limestone powder on the compressive response of high-early-strength portland cement mortars cured either in water or under ambient conditions. Nineteen mortar mixtures were classified into three groups based on the particle size distribution of the pulverized limestone powders: L (blaine = 3467 cm2/g), M (blaine = 4710 cm2/g), and H (blaine = 5764 cm2/g). The design equations for the compressive strength gain rates and stress–strain relationship of ordinary portland cement (OPC) concrete were adapted for the present mortars. The test results revealed that the 28-d compressive strength (fc′) of the mortars tended to decrease with an increase in limestone powder content, even for mortars containing 5 % limestone powder with small particle sizes. This contrasts with the common trend of the positive effect of limestone powder on the compressive strength of OPC concrete up to a certain substitution level. Furthermore, mortars containing finer limestone powders exhibited a greater rate of decrease in fc′, regardless of the curing conditions. The modified equations show promise for reliably assessing both the compressive strength gain rates at different ages and the stress–strain behavior of high-early-strength portland cement mortars containing limestone powders.

Effect of shell composition on watertightness and mechanical performance of cement-based capsules used as self-healing additives of cement

The aim of this work is the development of cementitious macro-capsules for self-healing cement and concrete materials. Emphasis is placed on shell properties, including size, thickness, strength, and volume to active component ratio. This enhancement is aimed at protecting the healing agent and ensuring adequate reactivity upon crack formation, surpassing survivability considerations. To this direction, core/shell particles have been produced following the pan-coating method, while different types and concentrations of setting acceleration solutions for the shell stabilization were studied. The formation of core-shell capsules encompasses the formation a spherical core through agglomeration, followed by simultaneous spraying of cement powder and a setting acceleration solution for the shell formation, under continuous rotation. The microstructural characteristics of the shell were studied through scanning electron microscopy (SEM), while the reactivity of the protected core (reactive agent) inside the hardened mortar mixtures was evaluated using thermogravimetric analysis (TGA). Moreover, the crushing load of the capsules under compression and their survivability during mixing process were examined and interpreted in relation to their diameter, circularity, and shell thickness.The results revealed the ability of the encapsulation methodology proposed to tailor the shell properties and modify the capsule properties so as satisfy the requirements of different applications. The use of setting accelerators during shell formation proved essential for enhancing the density and the strength of the shell layer. As a consequence, this leads to macro-scale capsules with elevated survivability rate and core reactivity.

Influence of ground slag and dune sand behavior of binary and ternary cement

This study examines the effect of slag and dune sand replacement (binary and ternary) in cement production, focusing on key mechanical properties and chemical behavior, especially on fire loss and residual an insoluble examined at different curing times ranging from 2 to 210 days. The findings show that the addition of slag and dune sand powder significantly influences the mechanical and thermal properties of mortar mixtures replaced by slag the compressive strength increases up to 30% and a slight decrease up to 40 is observed %. Ternary mixes show improved long-term compressive strength, especially after 120, 210 days, although generally young strength is lower than control When binary and ternary are combined with high flexural strength, ternary mixes exhibit good long-term performance, especially in mixtures of 20-30% slag and 10% dune sand lime (ACHOURA, D and al. 2008). From a thermal perspective, the replacement of slag with dune sand lime reduces losses during combustion, indicating excellent thermal stability. The addition of dune sand lime increases the proportion of impervious residue, indicating stability and durability of the cement. Overall, the study concludes that the proper use of slag and dune sand lime especially in ternary mixes can significantly improve the long-term mechanical and thermal performance of cement mortars Thus these findings provide valuable insights for designing building materials with higher durability and strength to suit specific construction application applications.

РОЛЬ САСО3 У ФОРМУВАННІ МІЦНІСНИХ І ДЕКОРАТИВНИХ ВЛАСТИВОСТЕЙ ПОРОШКОВОГО ЛУЖНО-АКТИВОВАНОГО ШЛАКОПОРТЛАНДЦЕМЕНТНОГО БЕТОНУ

The article discusses approaches to the formation of compositions of alkali-activated decorative Portland slag cements containing Portland cement type CEM1 5...45% with high performance and decorative properties. The optimization of the compositions of decorative alkali-activated Portland slag cements was carried out using statistical methods for designing experiments. Finely dispersed TiO2 and CaCO3 additives with a whiteness of 90% were used as bleaching components. The alkaline component is sodium metasilicate in the form of a non-hygroscopic powder. The research carried out made it possible to obtain decorative Portland slag cements with a whiteness of 45...77%, which allows them to be used to produce colored cements with a wide range of colors from white to black. It has been established that alkali-active decorative Portland slag cements have an activity of 37...59 MPa at the age of 28 days. All compositions have good hardening dynamics and, based on the strength at the age of 2 days  22...36.6 MPa, they can be classified as fast-hardening. Based on them, it is possible to produce dry construction mixtures. All mortar compositions based on alkali-active decorative Portland slag cements demonstrate fairly high frost resistance  F200. This allows them to be used for the manufacture of products and solutions both for indoor use and when exposed to atmospheric influences without loss of design characteristics and decorative appeal. The inherent shrinkage strains of decorative alkali-activated Portland slag cements are 0.51...0.61 mm/m, which eliminates cracking and premature destruction of products. The use of the CaCO3 additive is especially effective for controlling the shrinkage deformations. Thus, the CaCO3 additive performs the functions of not only a decorative component, but also a structure-forming component. Concrete and mortar mixtures can be used to produce decorative products using the traditional method, extrusion, 3D printing on construction printers, etc. And not too long setting times and a rapid increase in strength make it possible to produce products without thermal treatment or with minimal consumption of thermal energy.

Salt weathering resilience in masonry: An accelerated laboratory study involving wind-induced variations

Salt weathering resistance is a critical parameter governing the durability of coastal masonry units and mortars. Accelerated weathering cycles are employed at the laboratory to investigate the responses of substrates and mortars upon exposure to salt, moisture, temperature fluctuations and humidity. In this paper, the individual and synergistic performances of bricks and mortar formulations when exposed to accelerated salt weathering cycles are investigated, incorporating the influence of wind on their resilience. The study examines the behaviour of brick-mortar sandwich specimens and separate specimens of bricks and mortar mixtures comprising cement, dry hydrated lime, fly ash, and limestone. These specimens are exposed to repeated weathering cycles in a 5 % sodium sulphate solution. Along with the mass variations during each weathering cycle, physicomechanical, microstructural, mineralogical and morphological characterization of the specimens are used to compare their salt weathering resistance. The results highlight that the responses of individual masonry components might not collectively translate to the overall performance of the combined system due to hygric resistance, which is minimal when the components have comparable pore size distribution. Higher microporosity (pores of diameter between 0.1 μm and 10 μm) and mechanical strength enough to resist the crystallization stresses together provide better resistance to salt weathering to the individual mortars. However, pore structure compatibility and pore fraction similarity between the components govern the behaviour of the combined system and, therefore, reflect the better performance of sandwich specimens with brick and lime mortars. The study demonstrated that wind accelerates material degradation during salt weathering through progressive erosion, accelerated evaporation and subsequent formation of isolated thenardite.

Rapid Assessment of Sulfate Resistance in Mortar and Concrete.

Extensive research has been conducted on the sulfate attack of concrete structures; however, the need to adopt the use of more sustainable materials is driving a need for a quicker test method to assess sulfate resistance. This work presents accelerated methods that can reduce the time required for assessing the sulfate resistance of mixtures by 70%. Class F fly ash has historically been used in concrete mixtures to improve sulfate resistance. However, environmental considerations and the evolving energy industry have decreased its availability, requiring the identification of economically viable and environmentally friendly alternatives to fly ash. Another challenge in addressing sulfate attack durability issues in concrete is that the standard sulfate attack test (ASTM C1012) is time-consuming and designed for only standard mortars (not concrete mixtures). To expedite the testing process, accelerated testing methods for both mortar and concrete mixtures were adopted from previous work to further the development of the accelerated tests and to assess the feasibility of testing the sulfate resistance of mortar and concrete mixtures rapidly. This study also established criteria for interpreting sulfate resistance for each of the test methods used in this work. A total of 14 mortar mixtures and four concrete mixtures using two types of Portland cement (Type I and Type I/II) and various supplementary cementitious materials (SCMs) were evaluated in this study. The accelerated testing methods significantly reduced the evaluation time from 12 months to 21 days for mortar mixtures and from 6 months to 56 days for concrete mixtures. The proposed interpretation method for mortar accelerated test results showed acceptable consistency with the ACI 318-19 interpretations for ASTM C1012 results. The interpretation methods proposed for the two concrete sulfate attack tests demonstrated excellent consistency with the ASTM C1012 results from mortar mixtures with the same cementitious materials combinations. Metakaolin was shown to improve sulfate resistance for both mortar and concrete mixtures, while silica fume and natural pozzolan had a limited impact. Using 15% metakaolin in mortar or concrete mixtures with Type I/II cement provided the best sulfate resistance.

Effect of PCE anionic charge density on fly ash cementitious system-PCE compatibility

In this study, the compatibility of polycarboxylate-based water-reducing admixtures (PCEs) with cementitious systems containing fly ash (FA) was investigated. For this purpose, PCEs with carboxylate, phosphate, and sulfonate anionic groups having different anionic charge densities were synthesized. The effects of PCEs on fresh properties and compressive strength of cementitious systems containing FA were investigated. The PCE with 9% phosphate substitution and high anionic charge density was found to be the most effective, requiring the least amount for the target flow. Similarly, in terms of the PCE requirement for the minimum Marsh funnel flow time and rheological parameters, the best performance was obtained with 5% sulfonate substituted PCE having high anionic charge density. While FA had a positive effect on the PCE requirement and consistency retention of the mixtures; it had a negative effect on Marsh funnel flow time, rheological properties, and compressive strength. However, the rheological properties of the mortar mixtures were not adversely affected by the FA substitution as much as that of the paste mixtures. Regarding the 28-day compressive strength of mortar mixtures, the optimum FA substitution ratio was 15%. Fly ash substitution above this level reduced the compressive strength at all ages including 28-day strength. Anionic charge density variation of PCE had no significant influence on the compressive strength of the mortars.

Hydrothermal and mechanical performance of mortars containing waste brick powder

It is widely recognised that green building, environmental sustainability, and technical performance have recently become requirements in the field of civil engineering. For this reason, the new trend in research is to focus on the recycling and recovery of materials, even if some of them such as industrial waste are still underexplored. In this perspective, the main objective of this work is to study the influence of brick powder on the thermophysical and mechanical properties of mortars containing this type of waste, in different environments, and within the temperature range between ambient temperature and 50 °C. To this end, a number of mortar mixtures, in which cement was replaced by brick powder in different proportions, were studied and characterised according to technical standards in order to define the optimal substitution percentage. Three batches of samples were examined at different ages, i.e., 3, 7, 28, and 90 days. The samples of the first batch were kept in water at a temperature of 20 ± 2 °C with a relative humidity RH = 100 %, while those of the second batch were immersed and stored in water at 50 °C in order to simulate a hot and humid climate. As for the samples of the third batch, they were kept in a dry oven at 50 °C in order to investigate the effect of the hot and dry climate. The results obtained revealed that the partial replacement of cement by brick powder makes it possible to improve the thermal insulation characteristics but reduce the mechanical strength of the mortar. In addition, it was shown that in a hot and dry environment, the mechanical characteristics of the different mortars decrease as the rate of weight substitution of cement by brick powder rises. However, in a hot and humid environment, a reverse trend is observed. The findings also suggested that the optimal recommended rate of substitution of cement by brick powder is 20 %.

Mixture of biochar as a green additive in cement-based materials for carbon dioxide sequestration

Cement production for concrete is one of the main reasons why the building industry contributes significantly to carbon dioxide emissions. This paper investigates an innovative approach to utilizing CO2 by incorporating mixed biochar in mortar. Various dosages (0%, 3%, 5%, and 10%) of mixed biochar were explored to assess their impact on the structural properties and environmental sustainability. In this study, mixed biochar was prepared using the pyrolysis method, in which biomasses (rice husk and sawdust) were heated in the absence of oxygen for 2 h in a muffle furnace at the heating rate of 10 ℃/min to 550 ℃ with a 2-h holding time. The replacement of biochar was done with cement in a mortar mixture for casting the cubes followed by putting them in the carbonation chamber for 28 days curing. After that, the cured samples were tested for mechanical strength, porosity, density, and water absorption. X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA) showed that biochar supplementation promoted cement hydration products. Field emission scanning electron microscope (FESEM) analysis showed that several cement hydrates such as C-S–H, Ca(OH)2, and CaCO3 were formed with different doses of biochar and increased mechanical strength. Addition of 10 wt. % biochar increased the compressive strength of the composite by 24.2% than the control respectively, and successfully promoted the CO2 sequestration with 6% CO2 uptake after 28 days of accelerated CO2 curing. The present research has shown the benefits of optimally integrating mixed biochar with cement in the development of low-carbon, sustainable cementitious materials that have the potential to convert building materials like concrete in the future.

Life-Cycle Assessment and Environmental Costs of Cement-Based Materials Manufactured with Mixed Recycled Aggregate and Biomass Ash.

The development of new building elements, such as concrete and mortar with sustainable materials, which produce a lower carbon footprint, is an achievable milestone in the short term. The need to reduce the environmental impact of the production of cement-based materials is of vital importance. This work focuses on the evaluation of the life-cycle assessment, production costs, mechanical performance, and durability of three mortars and three concrete mixtures in which mixed recycled aggregates (MRAs) and biomass bottom ash from olive waste (oBBA) were included to replace cement and aggregates. Powdered MRA and oBBA were also applied as complementary cementitious materials with a reduced environmental footprint. Chemical and physical tests were performed on the materials, and mechanical performance properties, life-cycle assessment, and life-cycle cost analysis were applied to demonstrate the technical and environmental benefits of using these materials in mortar and concrete mixtures. This research showed that the application of MRA and oBBA produced a small reduction in mechanical strength but a significant benefit in terms of life-cycle population and environmental costs. The results demonstrated that finding long-term mechanical strength decreases between 2.7% and 14% for mortar mixes and between 1.7% and 10.4% for concrete mixes. Although there were small reductions in mechanical performance, the savings in environmental and monetary terms make the feasibility of manufacturing these cement-based materials feasible and interesting for both society and the business world. CO2 emissions are reduced by 25% for mortar mixes and 12% for concrete mixes with recycled materials, and it is possible to reduce the cost per cubic meter of mortar production by 20%, and the savings in the cost of production of a cubic meter of concrete is 13.8%.

Characterization of Phosphogypsum for Potential Uses in Soil Stabilization

This research investigated the influence of phosphogypsum (PG) addition to mortar mixture and determined the possibility of utilizing PG in soil stabilization. Originally, the chemical composition and mineralogy of the PG were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD) tests. The principal constituent of PG becomes calcium sulfate hemihydrate with the presence of some impurities. A total of 9 mixes have been developed: A plain mortar mix is a comparative base, and the other 4 mixes are with 5, 10, 15, and 20 % cement replacement with PG for each type (fresh and stockpiled PG called PGF and PGS, respectively). The experimental program focuses on analyzing the effects of PG on setting time, hardened density, compressive strength, and water expansion of mortar mixtures before its soil stabilization application. Test results indicate that with higher PG, the setting time of the mortar mix is delayed except for the mixture with 20% PG, which experienced an early false set. The results of the compressive strength tests revealed that the 5% PG mixes exhibited higher values compared to the control mix, starting from the 28-day curing period, regardless of PG type. Although the higher PG content and compressive strength lowered, the expansion levels were very low based on the ASTM C 1260 limits for all mixtures, excluding heaving risks.