Chloride Permeability Research Articles

Experimental study of porosity and permeability of stabilized earth blocks by date palm plant fibers

The physical behavior characteristics of stabilized earth blocks (SEBs) reinforced with date palm plant fibers (PFDP) are examined in this experimental investigation. Various compounds were prepared, including 0%, 5%, and 10% lime, 0%, 5%, and 10% cement, and a combination of 5% lime and 5% cement. Additionally, fibers were incorporated at rates of 0%, 0.25%, and 0.5% by weight for each of the compounds. The study of porosity and permeability was conducted using several methods, including total porosity estimation, total volume porosity in water, open porosity, water vapor permeability, chloride ion permeability, and hydraulic conductivity, over a period of 90 days. The findings indicated that the incorporation of fiber enhanced the porosity and connectivity of pores, resulting in increased permeability of the SEBs. The cement-based bricks demonstrated a greater effectiveness than lime in decreasing the porosity and permeability of the blocks. The formulation consisting of 10% cement and the blend of 5% lime with 5% cement demonstrated satisfactory outcomes regarding porosity and permeability. This indicates that these materials are suitable for use in construction applications that demand enhanced durability and resistance to both natural and chemical influences.

Effect of incorporating ultrafine palm oil fuel ash on the resistance to corrosion of steel bars embedded in high-strength green concrete

Abstract Durability degradation in reinforced concrete (RC) constructions is commonly attributed to the steel reinforcement corrosion caused by chloride. The utilization of supplemental cementitious resources, such as waste materials from industrial and agricultural sectors, typically improves the impermeability and strengthens concrete resistance to corrosion, sulfate, and acid attacks. Therefore, the prevention of steel reinforcement corrosion is greatly important in resolving challenges related to the durability and stability of RC structures, particularly when utilizing agriculture waste materials. This approach also serves as a solution for waste disposal. The aim of this study is to investigate the corrosion-resistant characteristics of high-strength concrete that contains ultrafine palm oil fuel ash (U-POFA) as a partial replacement for cement. Four high-strength green concrete (HSGC) mixes were investigated in this study with a partial replacement of ordinary Portland cement (OPC) by U-POFA at 0, 20, 40, and 60% by mass. The aim of this study is to analyze the workability, strength activity index (SAI), compressive strength, rapid chloride permeability, linear polarization resistance (LPR) by different measurement methods, and four-probe resistivity measurement by electrical resistivity measurement method of over a curing period of 7, 28, 60, and 90 days. The use of U-POFA in the different mixes results in improved workability, SAI, compression strength, and chloride penetration resistance compared with the zero-POFA mix. It is clear from the study results that adding U-POFA as a partial replacement for OPC improved the corrosion resistance of HSGC mixtures. Thus, the incorporation of U-POFA 60% succeeded in reducing the chloride ion penetration by 80% and the LPR by 93% at the test age of 90 days, compared to the reference mixture.

Interlayer Cohesion in 3D Printed Concrete: The Role of Width-to-Height Ratio in Modulating Transport Properties and Pore Structure

Due to the extrusion-based printing and layer-to-layer deposition characteristics, the interlayer cohesion of 3D printed concrete is highly sensitive to the geometry of the printed layers, significantly influencing both mechanical performance and long-term durability. In this study, the width-to-height (W/H) ratio was employed as a geometric parameter to explore its relationship with interlayer transport and pore morphology. The research began by optimizing mix proportions through fluidity and printability tests. Subsequently, chloride ion permeation, mercury intrusion porosimetry, and micro-CT were used to analyze interfacial transport and pore distribution, revealing the influence of the W/H ratio on these properties. The results demonstrate that the W/H ratio plays a crucial role in densification and interfacial defect formation in 3D printed concrete. While the extrusion process enhances matrix compaction, a higher W/H ratio generally promotes stronger interlayer cohesion and reduces chloride ion permeability. However, an excessively large W/H ratio, especially when coupled with air entrainment, can introduce defects and increase porosity at the layer interfaces. The study concludes that maintaining a W/H ratio between 1.5 and 2.0 effectively strengthens interlayer cohesion. These results offer valuable theoretical insights and technical support for the design and application of 3D printed concrete materials.

Effect of CO2 wet mineralized steel slag-granulated blast furnace slag composite admixture on mechanical properties and chloride corrosion resistance of mortar

Given the global emphasis on environmental issues, addressing the substantial quantities of steel slag and greenhouse gases produced by the steel industry has garnered significant attention from researchers worldwide. This research investigates the application of wet CO2 mineralization for the treatment of steel slag. The microstructure and phase composition of steel slag are analyzed and compared before and after the mineralization process using SEM, XRD, TG-DTA, and particle size analysis. Composite mineral admixtures were prepared by mixing steel slag and granulated blast furnace slag to replace 50% cement. The study examined the influence of varying quantities of mineralized steel slag in the admixture on the mechanical properties, chloride permeability and autoclaved stability of mortar. The effects were elucidated through the application of SEM, XRD, TG-DTA, FTIR and early hydration heat testing. The results show that a layer of mineralized shell is formed on the surface of steel slag following wet mineralization treatment, which strengthens the mechanical adhesion between cementitious materials. The calcite produced by the mineralization reaction acts as a nucleation agent and micro-aggregate in the cement hydration process, leading to a significant enhancement in the early strength of mortar. When the mineralized steel slag content is below 30%, it positively impacts the strength of mortar. When the content is below 20%, it has little effect on the chloride ion permeability of mortar.

Evaluating suitability of regression models in small data regimes using concrete with recycled copper tailings as a case study

The utilization of regression models for the prediction of construction material properties is well-established, yet their performance when applied to small datasets is still unclear. This study investigates the performance of different regression models combined with various data preprocessing techniques in contexts where data is limited. Specifically, the research focuses on evaluating the suitability of five regression models across nine different data processing scenarios using concrete with recycled copper tailing as a case study. This study aims to determine which combinations of regression models and preprocessing methods yield the most accurate predictions in small data regimes. This research is motivated by the necessity to enhance prediction reliability in the field of construction materials, where experimental data can often be scarce or costly to obtain. Within the study context, a dataset comprising 21 experimental specimens is used to evaluate the performance of the models on various concrete properties, including fresh density, compressive strength, flexural strength, pull-off strength, abrasion resistance, water penetration, rapid chloride ion permeability, and air permeability. Through rigorous evaluation involving a 10-fold cross-validation process to verify accuracy, the research demonstrates that selecting the optimal regression model and data preprocessing technique selection substantially improves prediction outcomes, even with limited data. The findings highlight the importance of this research, suggesting that even small datasets, when handled correctly, can provide robust insights.

Effect of a novel negative temperature early-strength agent in improving concrete performance under varying curing temperatures

This study investigates the effect of a novel negative temperature early-strength agent (NEA) in enhancing concrete performance under varying curing temperatures, with a discussion on the underlying mechanism through analysis of hydration products and microstructure.The results indicate NEA markedly accelerates early cement hydration, reduces setting time, and enhances compressive strength. Moreover, the efficacy of NEA is more pronounced at lower temperatures. With an optimal dosage of 3%, the incorporation of NEA leads to a remarkable 285.9% increase in compressive strength at 28 days under -5°C curing temperature. Despite accelerating cement hydration can induce increased chemical shrinkage, NEA effectively mitigates early freezing expansion under negative temperature and significantly diminishes chloride ion permeability. Higher temperatures facilitate early cement hydration but also compromise long-term hydration continuity. Consequently, the highest hydration degree and loweast porosity are observed at 28 days under 5°C curing temperature. NEA's air-entraining component introduces numerous superfine pores into the paste, augmenting early pore volume while optimizing pore structure. As the early-strength component fosters hydration, these pores undergo further filling and refinement, ultimately reducing the total pore volume at 28 days. This study provides insights into optimizing concrete performance in cold environments.

Effects of Na2SiO3/NaOH ratio in alkali activator on the microstructure, strength and chloride ingress in fly ash and GGBS based alkali activated concrete

In this study, the impact of alkaline solutions composed of various Na2SiO3/NaOH ratio and NaOH molarity on the strength, chloride ingress and chloride binding capacity of fly ash (FA) and ground granulated blast furnace slag (GGBS) based alkali activated concrete (AAC) was investigated. The microstructural properties of alkali activated binders (AAB) composites was also studied to understand its influence on the chloride permeability of AAC. Chloride permeability of concrete was tested by using the rapid chloride penetration test (RCPT) and by immersing concrete in NaCl solution (ASTM C1556). The compressive strength, chloride ingress and chloride binding capacity of AAC was compared with Portland cement-based concrete (OPC). Results showed that higher Na2O/SiO2 ratio in alkaline solutions resulted in a weak microstructure with, low strength and high chloride ingress. Concrete activated by alkaline solutions with Na2O/SiO2 molar ratio =1 (+3), exhibited greater compressive strength and resistance to chloride ion penetration. The increase of SiO2 concentration in alkaline solution greatly reduces the binding capacity of AAC while the bound chlorides increased with the NaOH molarity. No chemical chloride binding was observed in AAC but for OPC concrete, calcium salts formed in the microstructure after immersion in NaCl solution. Compared to OPC concrete, AAC showed superior performance in terms of strength and chloride diffusion making it a potential candidate for application in marine structures.

Development of sustainable self-healing engineered cementitious composites incorporating maximum amounts of natural pozzolan

In light of the scarcity of the most commonly used supplementary cementitious materials in Engineered Cementitious Composites (ECC), there is a pressing need to explore alternative materials to replace them. This paper considers the influence of integrating high amounts of natural Pozzolan (NP) on the sound and self-healing characteristics of ECC, including compressive and flexural strengths, deflections, cracking behavior, ultrasonic pulse velocity, rapid chloride permeability, and microstructure both before and after pre-cracking and recovery periods. NP contents at Portland cement (PC) ratios of 1.2, 1.5, 1.8, and 2.2 were explored, along with a combination of (50 % NP + 50 % slag)-to-PC ratio of 2.2. The results obtained indicate that superior self-healing properties can be achieved with the use of NP instead of slag, particularly at higher NP/PC ratios. Furthermore, the ductility of ECC significantly increased with the inclusion of NP, reaching more than twice the deflection capacity of the control specimens at various ages. The results of this research confirm the formation of additional C-A-S-H-type healing products as the outcome of the NP incorporation on the self-healing ability of ECC. In addition, the life cycle assessment analysis (LCA) highlights the significant reductions in energy consumption, CO2 emissions, and cost of ECC mixtures prepared with increased inclusion of NP, up to a 2.2 NP/PC ratio.

Performance Evaluation of Drying Shrinkage and Durability in Pavement Quality Concrete with Recycled Aggregate, GGBS and I-Crete

<p style="line-height:200%;text-align:justify;"><span>The study examines replacement of natural aggregates (NA) with Recycled Aggregate (RA) in Pavement Quality Concrete (PQC) M40 grade (M1) with 25%, 50%, 75% and 100% RA replacing NA in M2, M3. , M4 and M5 mixes. The compressive strength decreases with higher RA, but all mixes reach the target strength at 28 and 90 days. M5 was tested by adding Ground Granulated Blast furnace Slag (GGBS) in increments of 5% to 15% in M6, M7 and M8 to reduce the cement content. The main performance parameters include compressive strength, drying shrinkage, water penetration, Rapid Chloride Permeability Test (RCPT) at 28 and 90 days and sorptivity at 28 days. M5 reduced compressive strength but increased drying shrinkage, sorptivity, penetration depth and RCPT charge passage. Increasing the GGBS by 10% in M7 improved the strength, while increasing the GGBS by 15% in M8 decreased the strength compared to M1 and M5.</span> <span>To address strength degradation, the study incorporated 2% I-Crete along with GGBS in 5% increments from 15% to 35% in M9 to M13 mixes. M11 mix (2% I-Crete, 25% GGBS) showed better strength, reduced shrinkage and lower RCPT charge, ensuring better durability for SEM and XRD pavement applications.</span></p>

Assessment of the self-healing capacity of PVA fiber-reinforced composites by chloride permeability and stiffness recovery

This paper investigates the intrinsic ability of PVA fiber-reinforced cementitious composites to re-establish the durability properties of the uncracked state. Comparative chloride penetration tests are used as a direct measure to quantify the effect of self-healing on the chloride penetration resistance after cracking. Two different composites with cement to fly ash ratios of 1:1.5 and 1:2.0 were studied under the influence of healing periods of up to 28 days. After inducing cracks between 100 and 120 μm, samples were exposed to chlorides for 72 h and the resulting chloride penetration depth was compared to the unhealed state. Based on this procedure, a durability recovery index was proposed to quantify the material’s ability to re-establish its function as a protective layer after cracking. Results show that after 14 days of self-healing, chloride penetration through cracks was reduced between 81% and 99%. An extended healing period of 28 days leads to further reduction of the penetration depth to 84%–100%, indicating that most of the reaction takes place within the first 14 days of healing. While the stiffness recovery analysis showed that increasing cement content by 20% correlated with the formation of stronger healing products, no significant difference was found regarding crack closure.

Prediction Model for the Chloride Ion Permeability Resistance of Recycled Aggregate Concrete Based on Machine Learning

The chloride ion permeability resistance of recycled aggregate concrete (RAC) is influenced by multiple factors, and the prediction model for this resistance based on machine learning is still limited. In the paper, six impact factors (IFs), including the carbonation of recycled coarse aggregates (YN), the replacement ratio of recycled coarse aggregates (r), the bending load level (L), the carbonation time (t) and temperature (T) of RAC, and the replacement ratio of carbonated recycled fine aggregates (f), were considered to conduct a chloride penetration test on RAC. Based on the experimental data, four algorithms, including artificial neural network (ANN), support vector machine (SVM), random forest (RF) and extreme gradient boosting (XGBoost), were adopted to establish the machine learning prediction models and study the relationships between the electric flux of RAC and the IFs. The results showed that the predicted values of all four models were in good agreement with the experimental values, and the XGBoost model had the best prediction performance on the testing set. Based on the XGBoost model, the LIME method was adopted to solve the interpretability problem in the prediction process. The importance ranking of IFs on the electric flux was r > t > f > T > L > YN. A graphical user interface (GUI) was developed based on Python 3.8 software to facilitate the use of machine learning models for the chloride ion permeability resistance of RAC. The research results can provide an accurate prediction of the electric flux of RAC.

Bacillus cereus GS-5 immobilized sintered fly ash lightweight aggregate for strength, durability, and autonomous crack healing in bacterial concrete

This paper investigates the impact of ureolytic bacteria, specifically Bacillus cereus GS-5 immobilized sintered fly ash lightweight aggregate, on the self-healing, strength, and durability characteristics of the bacterial concrete. Different concentrations of bacterial cells (105 to 107 cells/mL) were used, and a part of conventional aggregate was replaced by microbe immobilized lightweight aggregate as part of producing concrete mixes. Various systematic tests, such as compressive strength, water absorption, rapid chloride permeability, and self-healing capability, were conducted after defined time intervals. The results of the experiments demonstrated that the compressive strength of the bacterial concrete increased by an average of 25.65% as compared to the control specimens. A simulated crack width of 0.5mm was successfully effectively healed in the specimen by microbial induced calcium carbonate precipitation. The SEM images confirmed the precipitation, structure, and dispersion of the calcium carbonate crystals, whereas XRD analysis revealed the formation of the calcite crystalline phases within the calcium carbonate crystals. Calcite precipitation resulted in reduced porosity of the bacterial concrete, which was confirmed by reduced chloride permeability (5% - 17%), water permeability (29% - 60%), and water absorption (3% - 32%) with respect to the control specimen. It has been concluded that Bacillus cereus GS-5 immobilized sintered fly ash lightweight aggregate would serve as an effective concrete admixture, providing advantages such as self-healing of cracks, better durability, and improved mechanical performances.

Properties and eco-cost effectiveness of concrete containing waste blast furnace slag and demolition waste

Abstract This work aims to develop eco-friendly, cost-effective concrete using ground granulated blast furnace slag (GGBFS) and recycled coarse aggregate (RCA). Seven concrete mixes are prepared with different combinations of RCA and GGBFS. Properties like 28-day compressive strength, rapid chloride permeability and abrasion resistance have been studied. Physical and microstructural investigations have been carried out to justify the variation in the properties. Moreover, environmental impact and cost-effective analyses are performed. It is found that the strength of concrete mix with 50% RCA and 45% GGBFS closely satisfies the desired strength for M25 grade concrete. Also, the mix has shown good resistance against abrasion and chloride permeability. Physical examination reveals that ITZ has played a significant role in the strength variation. Similarly, microstructural investigation reveals that the formation of voids due to RCA and the filling of the voids by GGBFS are the two phenomena responsible for variation in durability. Further, the negative environmental impacts and cost of concrete can be reduced up to 62.93% and 11.9%, respectively, compared to the control concrete using RCA and GGBFS. Since this mix provides desired strength and durability, environmental benefit and cost benefit over normal concrete, this concrete becomes eco-cost efficient.

Effect of Waste PET Fiber on the Mechanical Properties and Chloride Ion Penetration of Emergency Repair Concrete for Road Pavement.

This study evaluated the effects of adding waste PET fibers on the mechanical properties and chloride ion penetration of latex-modified ultra-rapid hardening cement concrete used for emergency road pavement repairs. The primary experimental variable was the content of waste PET fibers. The mechanical properties of the concrete were evaluated through compressive strength, flexural strength, and splitting tensile strength tests. Its durability was evaluated through chloride ion penetration, surface resistivity, and abrasion resistance tests. The experimental results were compared with the quality standards for emergency repair concrete set by the Korea Expressway Corporation. As a result, this study has enhanced the strength and resistance to chloride ions of latex-modified concrete by incorporating waste PET fibers. In the mixture with 3.84 kg/m3 of waste PET fibers, the compressive strength was 29.9 MPa at 4 h and 42.5 MPa at 28 curing days. The flexural strength was 6.0 MPa at 4 curing hours and 7.0 MPa at 28 days, and the splitting tensile strength was 4.5 MPa at 28 days of curing. The chloride ion permeability amount and abrasion depth were 1081C and 0.82 mm, respectively. The mixture with 3.84 kg/m3 of waste PET fibers has superior compressive strength, flexural strength, splitting tensile strength, chloride ion penetration, and surface resistivity compared to the mixture with 7.68 kg/m3. This result means that the waste PET fibers caused poor dispersion and fiber-balling within the concrete, leading to loose internal void structures when incorporated at 3.84 kg/m3. However, the abrasion resistance test showed better results for the mixture with 7.68 kg/m3 of waste PET fibers than the 3.84 kg/m3 mixture. Therefore, the test results indicated that 3.84 kg/m3 of waste PET fibers is the most effective for latex-modified concrete used in emergency road pavement repairs.

Investigating the influence of various metakaolin combinations with different proportions of pond ash and Alccofine 1203 on ternary blended geopolymer concrete at ambient curing.

This paper explores the use of a ternary blended geopolymer concrete (TBGPC) incorporating metakaolin (MK), pond ash (PA), and Alccofine 1203 (AF). Three combinations of MK (25%, 50%, and 75%) with varying proportions of PA and AF were prepared, validating against M30 grade cement concrete (CC). TBGPC was prepared with an 8 molarity sodium hydroxide, sodium silicate to sodium hydroxide ratio of 2.0, liquid to binder ratio of 0.5, and an ambient curing mode. For CC, a water to cement ratio of 0.42 and water curing mode were adopted. The mechanical properties and durability behavior of TBGPC and CC specimens were evaluated through compressive strength, rapid chloride penetration test, permeability test, sorptivity test, and water absorption test. The M50P35A15 mix demonstrated remarkable compressive strength improvements, showing a 203% increase over the CC mix at 1day and 250% by 3days. This trend continued with a 155% increase at 7days, 68% at 28days, and 52% at 90days, consistently outperforming the CC mix. Additionally, microstructure characteristics of the M50P35A15 mix were analyzed through SEM studies, providing validation for the observed strength development. Notably, M50P35A15 mix demonstrated substantially higher early and later strength gain. This enhancement in strength was attributed to the gradual densification of the microstructure over time and the formation of additional NASH and CASH gel in M50P35A15 mix. At 28days, the M50P35A15 mix exhibited excellent durability characteristics, with a Coulomb value of 1008, permeability of 10mm, sorptivity of 0.45mm/√min × 10-4, and water absorption of 1.07%. This study demonstrates the potential of MK, PA, and AF as viable materials for sustainable geopolymer concrete, offering a low-carbon alternative to traditional cement concrete with superior strength and durability aspects.

Response tests on the effects of particle size of waste glass sand and glass powder on the mechanical and durability performance of concrete

To investigate the effect of waste glass material particle sizes on the mechanical and durability properties of concrete, a two-phase experimental approach was conducted. First, comprehensive tests were performed to examine the effects of glass sand and glass powder of different particle sizes on concrete performance. Subsequently, based on the experimental results, an orthogonal test was designed to optimize the replacement amounts of composite particle sizes. The results indicated that an appropriate amount of glass sand can enhance the mechanical properties and durability of concrete, while excessive amounts or larger particle sizes may have adverse effects. The pozzolanic effect of glass powder also contributes to performance improvement, but the replacement rate should be limited to 20%. Under composite particle size conditions, the compressive, tensile, and shear strengths of concrete increased by 35.56%, 21.74%, and 13.79%, respectively, while durability significantly improved, with water absorption reduced by 20.73% and chloride ion permeability decreased by 63.10%. At a total replacement rate of 20%, the optimal proportions were determined to be 2.86% for 0.6 mm glass sand, 1.43% for 1.18 mm glass sand, 8.57% for 50–60 μm glass powder, and 7.14% for 60–70 μm glass powder. The incorporation of composite particle sizes improved the microstructure of concrete, thereby enhancing its mechanical and durability properties.

A New Performance-Based Test for Assessing Chloride-Induced Reinforcement Corrosion Resistance of Geopolymer Mortars.

The widespread adoption of geopolymer concretes in the industry has been slow, mainly due to concerns over their long-term performance and durability. One of the main causes of concrete structures' deterioration is chloride-induced corrosion of the reinforcement. The reinforcement corrosion process in concrete is composed of two main stages: the initiation phase, which is the amount of time required for chloride ions to reach the reinforcement, and the propagation phase, which is the active phase of corrosion. The inherent complexities associated with the properties of precursors and type of activators, and with the multi-physics processes, in which different transfer mechanisms (moisture, chloride, oxygen, and charge transfer) are involved and interact with each other, have been a major obstacle to predicting the durability of reinforced alkali-activated concretes in chloride environments. Alternatively, the durability of alkali-activated concretes can be assessed through testing. However, the performance-based tests that are currently available, such as the rapid chloride permeability test, the migration test or the bulk diffusion test, are only focusing on the initiation phase of the corrosion process. As a result, existing testing protocols do not capture every aspect of the material performance, which could potentially lead to misleading conclusions, particularly when involving an electrical potential to reduce the testing time. In this paper, a new performance-based test is proposed for assessing the performance of alkali-activated concretes in chloride environments, accounting for both the initiation and propagation phases of the corrosion process. The test is designed to be simple and to be completed within a reasonable time without involving any electrical potential.

The screening effect of coarse aggregate on the air void structure and durability of air-entrained concrete

The control of air void structures introduced by air-entraining agents (AEAs) has long been a crucial problem. However, the mechanism through which the air void structure is refined by the extrusion of the slurry and the cutting of the aggregate remains insufficiently studied. This study aims to investigate the screening effect of coarse aggregate on the air void structure. The gradations of coarse aggregates were controlled by the fractal dimension (D). For casting air-entrained concrete, multiple continuously graded aggregates with D of 2.1, 2.3, 2.5 and 2.7 as well as two single graded aggregates with D=1.8 and 3.0 were used. Various parameters such as air content, air void structure, freeze-thaw durability, chloride ion permeability and water absorption were measured. Various air void structure parameters were compared to macroscopic properties. To evaluate the screening effect of coarse aggregate, the bubble rising and splitting behavior when passing through a single simulated aggregate (SA) and SA layer were observed. The findings indicate that finer and continuously graded coarse aggregates lead to higher air content and promoted air bubble trapped rate, which suggests a stronger screening effect. This results in a smaller bubble spacing coefficient and stronger frost resistance.

Novel approaches to improving gas separation: Ionic liquids coated coke/ NH2-UiO-66-based mixed matrix membranes for CO2/N2 separation

Permeability and separation efficiency of mixed matrix membranes (MMMs) are two important aspects. Polymeric membranes offer excellent mechanical and physical properties; however, they have a low permeability. To enhance the permeability and separation performance of polyvinyl chloride (PVC) membranes, Cholinium amino acid-based (IL) were impregnated with activated coke/ NH2-UiO-66 (Zr) (AC/MOF) composite and then IL@AC/MOF filler was incorporated into PVC matrix. FTIR spectroscopy, TGA, SEM, EDX, and Brunauer-Emmett-Teller (BET) surface area measurement were used to characterize the MMMs prepared. The porous structure of MMMs nanocomposites causes AC/MOF composite to effectively accelerate gas the diffusion in the PVC matrix. The permeability measurements for CO2 and N2 were made at 288.15, 298.15, 308.15, and 318.15 K at pressure 3 bar The outcomes indicates that the incorporation of the IL@AC/MOF filler increased the permeability of the PVC/AC/MOF MMMs compared to the pure polymeric membrane. The mixed matrix membranes exhibit superior gas separation performance, surpassing the 2008 Robson's Upper Bound.

Experimental study on chloride ion permeability of carbonated recycled aggregate concrete considering the effects of multiple factors

The chloride ion permeability is an important index of durability of carbonated recycled aggregate concrete (CRAC), but the resistance to chloride ion permeability of CRAC is affected by many factors and has yet been fully explored, which needs further systematic study. Considering the effects of the replacement ratio of carbonated recycled coarse aggregate (CRCA), the carbonation time of CRAC, the bending load level, the carbonation temperature of CRAC, and the replacement ratio of carbonated recycled fine aggregate (CRFA), the resistance to chloride ion permeability of CRAC was investigated by conducting tests in this paper. The results indicated that, compared with the non-carbonated recycled aggregate concrete (NCRAC), the electric flux of CRAC decreased by 9.14–37.34 %. An increase in the replacement ratio of CRCA could reduce the resistance to chloride ion permeability of CRAC, while an increase in CRAC carbonation time had a significant effect on improving the resistance to chloride ion permeability. When the replacement ratio of CRCA was 100 %, as the carbonation time increased from 0 to 14 days, the maximum reduction in electric flux of CRAC was 31.66 %. With the same replacement ratio of CRCA, as the bending load level increased, the decrease in electric flux of CRAC showed an increasing trend compared to that of NCRAC. The resistance to chloride ion permeability of CRAC could be improved with an increase in carbonation temperature. Compared with the CRAC with carbonation temperature of 20 °C, the electric flux of the CRAC with carbonation temperature of 40 °C decreased by 11.03 %. When the replacement ratio of CRFA was in the range of 0–20 %, the resistance to chloride ion permeability of CRAC could be improved by incorporating CRFA, but the improvement effect was not significant. Therefore, compared with the NCRAC, the resistance to chloride ion permeability of CRAC is enhanced, and the research results can provide data support for the engineering application of CRAC.