Ion Penetration Research Articles

Research on crystalline admixtures for low carbon buildings based on the self-healing properties of concrete

The increasing fascination surrounding low carbon construction materials has propelled self-healing concrete into the realm of vital technologies for attaining low carbon objectives. This investigation through artificial cracking and precompression experiments demonstrates the efficacy of two specific crystalline admixtures (CAs), namely L-aspartic acid (LAA) and Ethylenediaminetetraacetic acid (EDTA), in augmenting the self-healing characteristics of concrete. The flexural and compressive strength as well as chloride ion diffusion coefficient tests, were used to evaluate the mechanical properties and durability, and the microstructures was analyzed by X-ray diffraction (XRD), differential thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM), Bruno-Emmett-Teller (BET) and mercury intrusion pore size measurement (MIP). The findings indicate that the optimum dosage for both LAA and EDTA is determined to be 0.5%. At this dosage level, these admixtures effectively fill the pores by stimulating the production of hydrated calcium silicate gel (CSH) and calcium carbonate, leading to a reduction in porosity, enhanced concrete compactness, and successful activation of the self-healing mechanism. Moreover, the incorporation of these admixtures results in improved strength grade and enhanced resistance against chloride ion penetration.

Chloride ion transport in unsaturated ultra-high performance concrete cracks under high hydraulic pressures

The high strength, durability, and impermeability of ultra-high performance concrete (UHPC) make it a vital material for the construction of deep underground facilities, such as tunnels, nuclear waste repositories, and research laboratories. However, the presence of cracks and high hydraulic pressure in deep underground greatly accelerates the transport of chloride ions, which can shorten the service life of UHPC. Unfortunately, the underlying mechanism for this is still unclear. Here, we investigated the influence of hydraulic pressure and capillary force on chloride ion transport in cracked UHPC using a self-designed testing module. It was found that the presence of trapped gas creates a gas–liquid two-phase state within the cracks. Theoretical models were established using the Laplace equation, which effectively describe the hindrance of gas within cracks on the transport of chloride ions. Contrary to current understanding, the primary driving force for chloride ion transport within the crack is the capillary pores along the crack walls, rather than the capillary forces associated with the crack itself. In addition, the unhydrated regions within the UHPC interior expedite the adsorption of water molecules compared to ordinary concrete. Hydraulic pressure significantly accelerates the depth of chloride ion penetration. Subsequently, the visualization of the solution within cracks was carried out through the application of X-ray computed tomography (X-CT) and capillary tests, thereby providing a means to validate the accuracy of the model. This study contributes to the advancement of our knowledge regarding the influence of capillary force and high hydraulic pressure on the transport of chloride ions. The findings have important implications for the analysis of the durability of UHPC structures situated in deep underground environments.

Effect of ion-induced secondary radiations on the formation of extended defects and radiolysis beyond the range of swift 12C, 50Ti, and 52Cr ions in LiF

The objective of this research is to study the role of ion-induced secondary radiations on structural damage in LiF crystals irradiated with ∼ 10 MeV/u energy 12C, 50Ti, and 52Cr ions using experimental methods of nanoindentation, Atomic Force Microscopy, optical absorption, depth-resolved photoluminescence and chemical etching. In LiF crystals irradiated at room temperature with 50Ti and 52Cr ions, the chemical etching method revealed formation of nano-sized colloids in a wide area (up to one mm) beyond the ion penetration depth. Annealing experiments on irradiated samples at temperatures above 620 K, show enhanced manifestations of radiolysis in ion-irradiated and beyond-range areas accompanied by the emission of radiolysis residues. The multicomponent secondary radiation following the ion-induced inelastic nuclear reactions is discussed as the plausible mechanism of the observed long-range damage.

Evaluating the rapid chloride permeability of self-compacting concrete containing fly ash and silica fume exposed to different temperatures: An artificial intelligence framework

One of the major known challenges of improving durability of concrete structures is reducing the permeability of concrete to retard the transport of chloride ions. In this regard, the utilization of self-compacting concrete (SCC) incorporating supplementary cementitious materials such as fly ash and silica fume can aid to improve the resistance against chloride ion penetration. With the aim of evaluating the effectiveness of the SCCs, existing experimental methods, such as the rapid chloride permeability test (RCPT), demand time, financial resources, and skilled technicians. This study proposes three accurate and reliable predictive models through the combination of metaheuristic optimization techniques of particle swarm optimization (PSO), ant colony optimization (ACO) and biogeography-based optimization (BBO) with artificial neural network (ANN) in order to minimize the reliance on time-consuming and costly laboratory activities. To this end, 360 RCPT results on 60 SCC mixtures incorporating various percentages of fly ash and silica fume exposed to different temperatures during the RCPT were collected. The performance of the developed models was assessed by different statistical indicators. The results reveal that the proposed ANN-BBO model exhibits a higher accuracy than the single ANN, ANN-PSO and ANN-ACO models. It is also found that the input parameter of the sample temperature during testing is the most important variable in controlling the RCPT of SCC with a contribution of 25%. Comparing the performance of the best proposed model (ANN-BBO) with that of existing models in the literature reveals that the ANN-BBO model has a higher accuracy in predicting the chloride ion penetration resistance of SCCs.

Natural bentonite as an internal curing agent in the production of eco-friendly ultra-high performance concrete with low autogenous shrinkage

This study investigated the use of natural bentonite as a green internal curing agent to prepare eco-friendly ultra-high performance concrete (UHPC) with low autogenous shrinkage and excellent heavy metal ions solidification properties. A method based on the pore fractal dimension analysis was used for assessing the performance of UHPC. Results showed the use of bentonite as a replacement of cement could effectively reduce the autogenous shrinkage through its internal curing effect without compromising the compressive strength and workability of UHPC. The UHPC containing 4% bentonite showed the best volume stability and durability, with a 26.9% reduction in the autogenous shrinking compared to the control UHPC. The addition of bentonite further improved ion penetration resistance and solidification of heavy metal ion owing to its ion exchange capacity. However, the enhancement effect decreased when the bentonite content was too high due to the volume change of bentonite. Two kinds of pore classification dimensions, Dmin and Dmax, were obtained from NMR results to build good correlations with the autogenous shrinkage and durability, respectively. Finally, the ecological evaluation demonstrated that the designed UHPC with bentonite had relatively low environmental impact compared to other internal curing material, which was promising to generate a cleaner product in the near future.

A comprehensive investigation on the impacts of steel slag aggregate on characteristics of high-performance concrete incorporating industrial by-products

Steel slag (SS), an industrial by-product of the steel industry, has the potential to serve as a natural aggregate alternative in concrete production to not only mitigate the exploitation of natural resources but also minimize the environmental impact of its treatment and disposal. This study was designed to investigate comprehensively the impacts of using SS as a full replacement for coarse aggregate and of using fly ash (FA) and ground granulated blast-furnace slag (GGBFS) as partial replacements for Portland cement on the engineering properties (i.e., workability, fresh unit weight, porosity, compressive and flexural strengths, ultrasonic pulse velocity, and drying shrinkage), durability (i.e., water absorption, surface electrical resistivity, and rapid chloride ion penetration), and microstructure (i.e., scanning electron microscopy observation) of high-performance concrete (HPC). A comparative analysis of the economic and environmental benefits of SS concrete versus natural aggregate concrete was also performed. The test results revealed that SS, FA, and GGBFS all impacted the properties of HPC significantly. The HPC mixtures in which natural aggregate had been completely replaced with SS exhibited about 20.4–21.3% higher unit weight than the natural aggregate concrete. The HPC samples with added FA and GGBFS exhibited enhanced performance in terms of mechanical strength, durability, and microstructure. Moreover, total material cost, global warming potential (GWP), and ozone depletion potential (ODP) were all found to be significantly lower in the HPC samples produced using SS and either GGBFS or a combination of FA and GGBFS. As a result, after 210 days of normal curing, the 100% SS concrete containing 15% FA and 35% GGBFS as a Portland cement substitution (S100F15G35 specimen) exhibited compressive and flexural strength values of 110.3 and 11.1 MPa, which were approximately 9.0% higher than the corresponding values of the reference concrete. Also, the S100F15G35 specimen registered the respective ultrasonic pulse velocity, surface electrical resistivity, and rapid chloride ion penetration values of 5328 m/s, 113.3 kΩ.cm, and 203 Coulombs, indicating high-quality and durable concrete. Moreover, incorporating 15% FA and 35% GGBFS in SS concrete resulted in a reduction of 15.7% drying shrinkage and 24.4% total material cost, especially reduced environmental impacts with a significant reduction in GWP and ODP by 43.5% and 29.2%, respectively. These findings further demonstrate the potential of using SS in combination with FA and GGBFS to create high-quality HPC that is both more economical and significantly more sustainable than conventional HPC.

Performance characterization and optimization of cement-lithium powder-grain slag composite cementitious materials

In this study, cement, lithium powder and grain slag were selected for compounding design with the aim of developing high performance cement-lithium powder-grain slag composite cementitious materials (CLG). Based on Mixture Design, 13 mixing ratios were designed and used to study the effect of CLG on the workability, mechanical properties, carbonation resistance, and chlorine ion penetration resistance of concrete through response surface plots (3D Plot), and a mathematical model between concrete properties and CLG was fitted. The hydration products and microscopic morphology were investigated using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the single mixing of lithium powder had a positive effect on the 28d compressive strength and carbonation resistance of concrete, but it was unfavorable to the fluidity and chlorine ion penetration resistance of concrete. Single admixture of grain slag has mainly improved the workability of concrete. The highest 28d compressive strength (47.3 MPa) of concrete with excellent workability and durability was achieved when cement, lithium powder and grain slag were compounded in the ratio of 75 %, 20 % and 5 %. Microanalysis showed that the hydration reaction at 28d was higher when lithium powder and grain slag were compounded, producing more hydrated calcium silicate (C-S-H) and enhancing the compactness of the concrete matrix. As a result, the late strength, chloride penetration resistance and carbonation resistance of the concrete were optimized. The results of multi-objective optimization showed that the best overall performance of concrete was obtained with the ratio of cement, lithium powder and grain slag of 79.3 %: 10.3 %: 10.4 %. Therefore, the design method of CLG provides new ideas for the efficient utilization of industrial wastes and the development of other high-performance composite cementitious materials.

Strength, durability, and impact behavior of recycled aggregate concrete with polypropylene aggregate

Massive consumption and production of plastic is expected to have a significant environmental impact in the near future. Plastic waste from landfills can be refined and recycled as aggregates in concrete through subsequent processing. Several studies have already been conducted using plastic scraps as aggregate in concrete. However, more research is needed before it can be incorporated into structural concrete. Therefore, this study aims to investigate the static and dynamic behavior of concrete made with polypropylene plastic aggregate (PPA) obtained from waste plastic materials. Natural coarse aggregate (NCA) and recycled concrete aggregate (RCA) are partially replaced with PPA in this study and drop impact tests are performed after the samples are exposed to room and elevated temperatures (200 °C and 400 °C). PPA replacement percentages are 0, 5, 10, and 15 %. The drop impact test is performed on both cylinders (150 mm × 63.5 mm) and beams (100 × 100 × 500 mm) specimens. Different mechanical and durability tests are also investigated. The impact energy decreases by up to 68 percent as the PPA percentage increases at room temperature. Furthermore, when the specimens are heated to 200 °C or 400 °C, the impact blows are significantly reduced (6–13 no). After being heated to 200 °C and 400 °C, the 15 percent NCA replaced cylinder loses 87 percent and 91 percent of its impact energy, respectively. In terms of mass loss, the control cylinder has a higher loss than the PPA cylinders, indicating that the presence of PPA in concrete causes less damage. In terms of mechanical properties, the 5 percent PPA-based concrete outperforms the control. Depending on the concrete age and coarse aggregate types, a 5 % PPA content increases compressive strength by up to 11.6 percent. In terms of durability, the water absorption tendency increases with increasing PPA content, and all-natural PP concrete (NPC) and recycled PP concrete (RPC) exhibit moderate to very low chloride ion penetrability. Overall, it is proposed that 5 % PPA be used with NCA and RCA for structural applications.

An approach for environment protection by regression and cluster analysis of GGBS-based geopolymer composite at different proportion of brick dust

The study focused on the significance of ground granulated blast furnace slag (GGBS) as replacement of brick dust. Compression, tension, rapid chloride permeability test (RCPT) and water absorption test (WA) is analyzed. Study revealed that the produced geopolymer concrete showed better properties over normal concrete. Up to 10% GGBS replacement with calcined clay, exhibits enhanced compressive strength. Chloride ion permeability tests showed that GPC is superior to normal concrete of all ages in its resistance to chloride ion penetration. On increasing brick dust proportion, mass loss minimized due to sulfate attack. Compressive strength has low relationship with water absorption (0.6618).

Value-added utilization of ultrafine ferronickel slag as a novel type of high-quality mineral admixture: A feasibility study

In this study, a novel type of high-quality mineral admixture, ultrafine ferronickel slag, is manufactured and designed, and the feasibility of its utilization in cement and concrete is systematically investigated. It was found that after mechanical grinding, ultrafine ferronickel slag can be used as a novel and special high-quality mineral admixture, which improves the microstructures and properties of concrete in an efficient way. Ultrafine ferronickel slag shows little adverse effect on the early-age strength, and effectively increases the later-age strength of concrete. It improves the resistance to chloride ion penetration and the resistance to sulfate attack of concrete. It also reduces the total porosity and refines the pore in concrete. With the increase of ultrafine ferronickel slag content, the proportion of large pores with diameters more than 100 nm decreases, and the proportion of pores with diameters less than 100 nm increases significantly, especially for the small pore with diameters less than 10 nm. In addition, ultrafine ferronickel slag presents good compatibility with polycarboxylate superplasticizer and significantly produces a pozzolanic reaction consuming portlandite. This study provides a new way for the value-added utilization of ferronickel slag and promotes the sustainable development of high-quality active mineral admixture in alternative binder design.

Review of the Influence of Acrylate Lotion on the Properties of Cement-Based Materials.

Polymer-modified cement-based materials have been widely used in the construction field. Acrylate lotion significantly improves durability, toughness, and bending resistance, especially durability, because the porosity of cement-based materials is reduced, preventing the entry of harmful ions and water. When acrylate lotion was at 20%, the resistance of cement-based materials to chloride ion penetration increased by 40%. At the same time, the fracture toughness of cement-based materials modified with acrylate lotion and carbon nanotubes increased by 10-15%. The flexural strength of cement-based materials modified by acrylate lotion and fiber increased by 29%. Additives such as TiO2 have a unique impact on the modification of cement-based materials, which has attracted the interest of researchers. This paper reviewed the performance of acrylate lotion-modified cement-based materials and the application of acrylate lotion in the field, which systematically increased the durability, mechanical properties, and waterproof properties of cement-based materials when acrylate lotion was modified, acrylate lotion was modified with nanomaterials, acrylate lotion was modified with other polymers, acrylate lotion was modified with fiber, and when acrylate lotion was modified with other additives. The shortcomings of acrylate lotion modification with different materials were reviewed and evaluated, and the comprehensive performance of cement-based materials modified by acrylate lotion was expected to achieve maximum strength improvement under the synergistic effect of various modifications.

Synthesis of mesoporous carbon particles with different pore sizes by soft template method

The Stöber method provides a facile procedure for making carbon spheres with controlled particle sizes and is considered to be low-cost. In this study, a facile method has been established for synthesizing porous carbon spheres with variable pore sizes using a modified Stöber process. The influence of acid treatment and manipulating the carbonization process heating rate on the pore size and morphology of the particles was investigated by nitrogen adsorption, Scanning Electron Microscopy (SEM), Powder X-ray diffraction (XRD), Raman and Fourier Transform Infrared Spectroscopy (FTIR). According to the results, carbon spheres were in the size range between 1 and 7 microns. Pore size characterization shows that the pore diameter has increased by increasing the heating rate as well as by performing acid treatment. Tunable pore sizes from 2.25 to 8 nm have been evidenced by the experiments. These synthesized mesoporous carbons with different pore sizes which facilitate penetration of molecules and ions are promising as effective materials for adsorption, encapsulation and material delivery applications.

FORMATION OF DEFECTS IN THE ANION AND CATION SUBLATTICE OF MgAl<sub>2</sub>O<sub>4</sub> CRYSTALS IRRADIATED BY HIGH ENERGY XENON IONS

In this work, the optical characteristics of an aluminum-magnesium spinel irradiated with 220 MeV Xe ions, which simulate the effect of nuclear fuel fission fragments were studied. During the experiments, the transmission spectra were measured in the IR region (240–12500) cm−1, the optical absorption spectra in the range (2–7) eV, the Raman spectra were measured by the ion penetration depth, from the surface to 30 µm. In the optical absorption spectrum (2–8) eV of irradiated spinel crystals, a wide complex band of radiation-induced absorption is observed with a peak in the region of 5.3 eV associated with electronic color centers of the F + and F type, and hole color centers are responsible for optical absorption at ~ (3–4) eV. In the near IR region, the crystal retains its transparency. In the Raman spectrum, in addition to the Raman modes characteristic of an ideal crystal, additional modes, A1g* (720 cm−1), and Eg* (385 cm−1), appear mainly in the form of an asymmetric shoulder of the main Eg mode. As the depth increases, the A1g*/Eg ratio increases, reaching a maximum value of 0.05 at 6 µm, and remains practically unchanged until the end of the Xe ion range of 14 µm, and with a further decrease to 0.045 at a depth of 30 µm. That is, when irradiated with 220 MeV Xe ions, cation mixing occurs along the ion path.

Mechanical properties of polyolefin and polypropylene fibers-reinforced concrete–An experimental study

Concrete, a widely used construction material, exhibits inherent brittleness and limited tensile strength. To address these shortcomings, the incorporation of fibers has gained prominence, with polyolefin and polypropylene fibers emerging as promising reinforcements. This study experimentally conducted and examined the mechanical characteristics of polyolefin and polypropylene fibers-reinforced concrete. The study involved conducting compressive strength tests and durability tests, including sulfate resistance, acid resistance, chloride ion penetration resistance, and abrasion tests. The results demonstrated a notable enhancement in the compressive strength of both cubic and cylindrical specimens with varying dimensions, owing to the inclusion of polyolefin fibers. Polyolefin fibers exhibited a greater reinforcing effect compared to polypropylene fibers, especially in larger cubic specimens and cylindrical specimens. The quantitative results show that specimens with polypropylene fibers exhibited a 9.67 % improvement in compressive strength, while those with polyolefin fibers showed a 30.47 % enhancement compared to specimens without fibers. The acid resistance test revealed that both types of fiber-reinforced specimens exhibited higher compressive strength in acidic environments compared to plain concrete specimens. In the chloride ion penetration resistance test, the polyolefin fiber-reinforced specimen demonstrated the highest resistance to degradation, while the plain concrete specimen exhibited the lowest resistance. Polyolefin demonstrated superior reinforcement compared to polypropylene, with a 35 % increase in acid resistance and better chloride ion resistance. In contrast, specimens without fibers weakened by 35.36 % in a chloride environment. The sulfate resistance test showed that the polyolefin fiber-reinforced specimen had the highest compressive strength in a sulfate environment, while the plain concrete specimen had the lowest. In sulfate and abrasion tests, polyolefin-fiber-reinforced specimens displayed the highest resistance and the lowest abrasion rate of 34.6 %. These findings highlight the potential of polyolefin fiber-reinforced concrete for enhancing mechanical properties and durability in various applications.

Durability of mortar and concrete containing pozzolans as a partial cement replacement in the marine environment: a review

This paper reviews the durability of concrete containing pozzolans in marine environments, which mainly focuses on resistance to chloride ion penetration and sulfate attack. The results of previous literature showed that the main ions of seawater are almost similar but the salinity varies with location. The mechanism of chemical reaction between seawater and concrete was carefully reviewed and explained. Besides, the main attacks that caused the degradation of concrete structures in marine conditions were summarized. The results of previous research indicated that using pozzolans (fly ash, slag, metakaolin, rice husk ash, etc.) as a partial cement replacement in concrete improved the durability of concrete such as resistance to chloride ion penetration and resistance to sulfate. The use of pozzolans not only improves the durability of concrete in the marine environment but also solves environmental impacts such as reducing CO2 emissions and landfilling areas. It can be concluded that the utilization of pozzolans in concrete, particularly in marine concrete structures is a promising approach for sustainable development.

Durability of mortar and concrete containing pozzolans as a partial cement replacement in the marine environment: a review

This paper reviews the durability of concrete containing pozzolans in marine environments, which mainly focuses on resistance to chloride ion penetration and sulfate attack. The results of previous literature showed that the main ions of seawater are almost similar but the salinity varies with location. The mechanism of chemical reaction between seawater and concrete was carefully reviewed and explained. Besides, the main attacks that caused the degradation of concrete structures in marine conditions were summarized. The results of previous research indicated that using pozzolans (fly ash, slag, metakaolin, rice husk ash, etc.) as a partial cement replacement in concrete improved the durability of concrete such as resistance to chloride ion penetration and resistance to sulfate. The use of pozzolans not only improves the durability of concrete in the marine environment but also solves environmental impacts such as reducing CO2 emissions and landfilling areas. It can be concluded that the utilization of pozzolans in concrete, particularly in marine concrete structures is a promising approach for sustainable development.

Surface phenomena and electrochemical behavior of phosphate ion incorporated titania nanotubes for boosting bone cell growth

The addition of bone-native calcium and phosphate ions to implant materials can improve biocompatibility. The objective of the work was a comprehensive analysis of phosphate incorporation in nanotubes utilising orthophosphoric acid as the electrolyte and its effect on nanotube development during anodization process. Also, the material’s biological compatibility was investigated. A traditional anodization method was utilised to create nanotubes on commercially pure titanium (Cp-Ti) metal surfaces. The creation of nanotubes was detected at an optimal concentration of orthophosphoric acid, while other experimental variables such as voltage, time, temperature, etc. were maintained constant. The surface phenomena of anodized TIOP’s were examined through High-resolution scanning electron microscopy (HR-SEM), X-ray diffraction (XRD) analyser and contact angle. Fourier transform RAMAN study validated the penetration of phosphate ions into nanotubes. Potentiodynamic polarisation investigation in SBF was used to analyse the corrosion behaviour of anodized TIOP’s surface and Scanning Electrochemical Microscopy (SECM) mapped the reactive surface of the anodic oxide layer. The biomineralization studies were performed for 14 days in SBF and analysed with SEM/EDX and ATR-FTIR. The cell compatibility of the anodized sample surface was carried out in the MG63 cell line. The result indicated the addition of bone-native phosphate ions to anodized surface influences the differentiation of cells. The apatite formations on anodized surface influence the corrosion behaviour of the sample and result in high corrosion resistance in SBF.

Durable Structural Concrete Produced with Coarse and Fine Recycled Aggregates Using Different Cement Types

The durability properties of structural recycled aggregate concrete (RAC) produced with 50% coarse recycled concrete aggregates and up to 20% fine recycled concrete aggregates were analysed and compared to those of conventional concrete (NAC). Both the RAC and NAC mixtures achieved the same compressive strength when using an effective water–cement ratio of 0.47 and 0.51, respectively. All the concretes were produced using three types of cement: CEM II A/L 42.5 R, CEM II A/S 42.5 N/SRC and CEM III/B 42.5 N-LH/SR. The properties of drying shrinkage, chloride permeability, and accelerated carbonation coefficient of the concretes were determined experimentally, and the obtained results were compared with the values estimated by specific standards of exposure to XC1–XC4 (corrosion induced by carbonation can happen due to the presence of humidity) and XS1 (corrosion caused by chlorides from seawater) environments. The results showed that all the concretes achieved maximum drying shrinkage for use in structural concrete. Any concretes produced with CEM IIIB, including the RAC-C50-F20 concrete, achieved very low chloride ion penetrability, ranging between 500 to 740 Coulombs. In addition, all concretes manufactured with CEM IIAL and CEM IIAS, including RAC-C50-F20, were suitable for use in XC3 and XC4 exposure environments, both with 50- and 100-year lifespans.

A Study on the Applicability of Waste Glass Wool and Waste Mineral Wool as Fiber Reinforcement

Recently, the handling of waste industrial resources has become an issue, and the importance of sustainable resources has increased. Among these waste industrial materials are glass wool and mineral wool, which are fibrous materials used as insulation materials with characteristics such as sound absorption, insulation, and non-flammability. However, after their service life, glass wool and mineral wool used for insulation are generally buried or incinerated, causing problems such as air and soil contamination. This research was conducted to examine the applicability of waste glass wool and mineral wool obtained from expired insulation as fiber reinforcement in cement concrete. The research aimed to evaluate the fresh concrete properties, strength properties, and durability properties by adding waste glass wool and waste mineral wool up to 0.5–2.0% of the cement weight. Regarding the slump and air content of fresh concrete, the results showed that the addition of waste fibers within this range did not significantly affect the air content. However, the slump decreased as the addition amount increased due to the high absorption, which is a characteristic of the fibers. In addition, the evaluation of strength revealed that the incorporation of fibers decreased the compressive strength compared to the reference concrete. However, the tensile strength increased due to the load-supporting function of the waste fibers. In the evaluation of freezing–thawing resistance and chloride ion penetration resistance, it was confirmed that the freezing–thawing resistance improved in all cases where waste glass wool was added. The chloride ion penetration resistance was found to be similar to that of the reference concrete. However, in the case of waste mineral wool, it was observed that an addition rate of more than 2.0% of fibers was required to ensure freezing–thawing resistance. As the addition rate increased, the total charge passed (permeability) increased significantly, leading to a decrease in chloride ion penetration resistance.

Multi-Criteria Optimization of Cost-Effective and Environmentally Friendly Reactive Powder Concrete Incorporating Waste Glass and Micro Calcium Carbonate.

In pursuit of developing an eco-friendly and cost-effective reactive powder concrete (RPC), we utilized a multi-objective optimization technique. This approach pivoted on the incorporation of byproducts, with a spotlight on ground glass powder (GP) as a pivotal supplementary cementitious material (SCM). Our goal was twofold: engineering cost-efficient concrete while maintaining environmental integrity. The derived RPC showcased robust mechanical strength and impressive workability. Rigorous evaluations, containing attributes like compressive strength, resistance to chloride ion penetration, ultrasonic pulse speed, and drying shrinkage, highlighted its merits. Notably, the optimized RPC, despite an insignificant decrease in compressive strength at 90 days compared to its traditional counterpart, maintained steady strength augmentation over time. The refinement process culminated in a notable 29% reduction in ordinary Portland cement (OPC) usage and a significant 64% decrease in silica fume (SF), with the optimized mix composition being 590 for cement, 100 for SF, 335 for GP, and 257 kg/m3 for calcium carbonate. Additionally, the optimized RPC stood out due to the enhanced rheological behavior, influenced by the lubricative properties of calcium carbonate and the water conservation features of the glass powder. The reactive properties of SF, combined with GP, brought distinct performance variations, most evident at 28 days. Yet, both mixtures exhibited superior resistance to chloride, deeming them ideal for rigorous settings like coastal regions. Significantly, the RPC iteration, enriched with selective mineral admixtures, displayed a reduced tendency for drying-induced shrinkage, mitigating potential crack emergence.