Durability Performance Research Articles

Tensile strength and durability performances-based evaluation of 3D-printed and mold-cast fibrous geopolymer composites produced at various alkaline activator combinations

This study aimed to investigate the effects of the sodium silicate-to-sodium hydroxide ratio, SH molarity, and carbon fiber volume fraction on the tensile strength and durability properties of mold-cast and 3D-printed geopolymer composites, including flexural and splitting tensile strengths, ultrasonic pulse velocity, water absorption, sorptivity index, and chloride penetration properties. For that purpose, the ground-granulated blast furnace slag and fly ash were employed as alumino-silicate-rich raw material. In order to activate the alumino-silicate-rich raw material, two sodium silicate/sodium hydroxide ratios of 1 and 2 and three sodium hydroxide molarities of 8M, 10M, and 12M were designated. Furthermore, carbon fiber was incorporated into the geopolymer composites at three volume fractions: 0%, 0.3%, and 0.6%. In total, 18 nonfibrous and fibrous geopolymer composites were manufactured in two different ways: mold-cast and 3D-printed. The findings demonstrated that the strength and durability characteristics of 3D-printed specimens were inferior to those of mold-cast specimens, attributed to the presence of weak interfacial bonds between layers. It has been observed that the incorporation of carbon fiber has the effect of improving tensile strength performance. Nevertheless, the addition of carbon fiber led to a slight decrease in UPV values, and an increase in water absorption and sorptivity index values. Also, it adversely influenced the chloride penetration of geopolymer composites. The findings of the study also indicated that increasing the sodium hydroxide molarity had a positive impact on the strength and durability properties of the composites. Nevertheless, it was observed that increasing the sodium silicate-to-sodium hydroxide ratio led to a decrease in both tensile strength and durability performances. Additionally, the microstructure of the geopolymer composites was analyzed using scanning electron microscope (SEM) images.

Long-term investigation of uniaxial compressive and self-sensing performances of ultra-high performance seawater sea-sand concrete incorporating superfine stainless wires: Insights into underlying mechanisms and theoretical models

Developing intrinsic self-sensing concrete is expected to provide a digital intelligence solution to address the infrastructure’s challenges in terms of safety, lifespan, resilience, and carbon emission reduction. Using seawater and sea-sand as well as corrosion-resistant conductive fillers to fabricate self-sensing ultra-high seawater sea-sand performance concrete (UHPSSC) with outstanding mechanical and durability performances is the prerequisite for realizing localized resource utilization and in-situ monitoring of marine infrastructure. However, the potential effect of ions from seawater and sea-sand on the long-term stability of mechanical and electrical performances cannot be ignored. This paper presents a long-term investigation of uniaxial compressive, electrical, and self-sensing performances of superfine stainless wires (SWs) reinforced UHPSSC under natural curing. The results show that incorporating 1.5% SWs improves the compressive strength, elastic modulus, peak strain, and toughness of UHPSSC by 25.0%, 11.7%, 33.8%, and 119.2%, respectively. The established statistical damage constitutive models based on Weibull strength theory highlight the roles of SWs in delaying crack initiation. The dense microstructure of SWs-reinforced UHPSSC inhibits the growth of expansive hydration products formed by corrosive ions, thus guaranteeing its long-term strength development. Additionally, due to incorporating 1.5% SWs, the electrical resistivity of UHPSSC is reduced by seven orders of magnitude, with a strain sensitivity of 119.1 under monotonic compressive loading and a monitoring stress range of 0-148.4 MPa, indicating that SWs-reinforced UHPSSC can sense its stress and strain while providing early warning of crack initiation and propagation. Benefiting from the rust-free property, micron diameter, and high aspect ratio of SWs, the primary conductive path of composites comprises the overlapping networks formed by low-content SWs, which are not influenced by the ion conduction of conductive ions. Hence, SWs-reinforced UHPSSC exhibits stable electrical resistivity and sensitivity during long-term curing, suggesting its considerable potential for long-term in-situ monitoring of marine infrastructure.

Comparative Analysis of Mechanical Characteristics: Ultrasonically Compacted vs. Conventionally Additive Manufactured Polymeric Samples

This scientific paper presents a comparative analysis of the mechanical characteristics of PLA samples fabricated through conventional AM methods and AM then ultrasonically compacted. The study aims to assess the potential advantages and limitations of ultrasonic compaction of PLA AM samples, as a reinforcing manufacturing technique. The methodology involves the fabrication of PLA samples using AM processes, then ultrasonically compact part of them to make a comparative study on their mechanical characteristics, including tensile strength. Additionally, the surface morphology and internal microstructure of the samples are analysed using microscopy techniques. The results of the study provide insights into the mechanical performance and structural integrity of the ultrasonically compacted samples compared to the conventionally PLA AM samples. The findings highlight any potential improvements or limitations in terms of mechanical properties, such as strength, durability, and overall performance.

A compliant mechanism actuated bistable hybrid mode triboelectric nanogenerator

Abstract Triboelectric nanogenerators (TENGs) working in sliding mode offer higher power generation capability compared with those working in contact-separation mode (CS-TENGs). However, unlike CS-TENGs, sliding action can limit TENG lifespan due to wear and tear. A TENG combining both modes with intermittent sliding actions can overcome this limitation. In this study, we propose a bistable hybrid mode TENG (BHM-TENG) that can leverage the functionalities of the traditional sliding TENG and CS-TENG and achieve both durability and satisfactory performance, enabled by a compliant mechanism design. A self-rotating base introduces sufficient sliding during intermittent contact, leading to significant improvement in charge transfer (44%) and voltage output (58%) compared with the conventional TENGs while minimising wear and tear. The prototyped device, excited using compliant beams, can be effectively actuated even at extremely low input frequencies (<0.1 Hz), as explained by a mathematical model. The real-world energy harvesting applications enabled by BHM-TENG is proposed based on the output of BHM-TENG.

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.

Mitigating the Kinetic Hysteresis of Co-Free Ni-Rich Cathodes via Gradient Penetration of Nonmagnetic Silicon.

Co-free Ni-rich layered oxides are considered a promising cathode material for next-generation Li-ion batteries due to their cost-effectiveness and high capacity. However, they still suffer from the practical challenges of low discharge capacity and poor rate capability due to the hysteresis of Li-ion diffusion kinetics. Herein, based on the regulation of the lattice magnetic frustration, the Li/Ni intermixing defects as the primary origin of kinetic hysteresis are radically addressed via the doping of the nonmagnetic Si element. Meanwhile, by adopting gradient penetration doping, a robust Si-O surface structure with reversible lattice oxygen evolution and low lattice strain is constructed on Co-free Ni-rich cathodes to suppress the formation of surface dense barrier layer. With the remarkably enhanced Li-ion diffusion kinetics in atomic and electrode particle scales, the as-obtained cathodes (LiNixMn1-xSi0.01O2, 0.6≤x≤0.9) achieve superior performance in discharge capacity, rate capability, and durability. This work highlights the coupling effect of magnetic structure and interfacial chemicals on Li-ion transport properties, and the concept will inspire more researchers to conduct an intensive study.

Mitigating the Kinetic Hysteresis of Co‐Free Ni‐Rich Cathodes via Gradient Penetration of Nonmagnetic Silicon

AbstractCo‐free Ni‐rich layered oxides are considered a promising cathode material for next‐generation Li‐ion batteries due to their cost‐effectiveness and high capacity. However, they still suffer from the practical challenges of low discharge capacity and poor rate capability due to the hysteresis of Li‐ion diffusion kinetics. Herein, based on the regulation of the lattice magnetic frustration, the Li/Ni intermixing defects as the primary origin of kinetic hysteresis are radically addressed via the doping of the nonmagnetic Si element. Meanwhile, by adopting gradient penetration doping, a robust Si−O surface structure with reversible lattice oxygen evolution and low lattice strain is constructed on Co‐free Ni‐rich cathodes to suppress the formation of surface dense barrier layer. With the remarkably enhanced Li‐ion diffusion kinetics in atomic and electrode particle scales, the as‐obtained cathodes (LiNixMn1−xSi0.01O2, 0.6≤x≤0.9) achieve superior performance in discharge capacity, rate capability, and durability. This work highlights the coupling effect of magnetic structure and interfacial chemicals on Li‐ion transport properties, and the concept will inspire more researchers to conduct an intensive study.

Mechanical and durability performance of eco-friendly geopolymer-stabilized soil

This work compared the mechanical performance and the durability of clayey soil stabilized using mechanochemically activated geopolymer (MAG) with conventionally activated geopolymer (CAG). The effect of ground-granulated blast-furnace slag (GGBS) content on the long-term durability of geopolymer-stabilized soil has also been studied. The samples of geopolymer stabilized soils were immersed in 1% magnesium sulphate (MgSO4) solution for 60 and 120 days. The appearance, ultrasonic pulse velocity, unconfined compressive strength (UCS), and FTIR spectroscopy of those samples were considered to evaluate their sulphate erosion resistance. Before the exposure to the MgSO4 solution, the UCS of MAG samples was higher (12%–45%) than that of CAG-stabilized soil. Furthermore, the strength of the geopolymer-stabilized soil improved by 114%, 247%, and 361%, at 50%, 75%, and 100% GGBS content, respectively. After exposure to the MgSO4 solution, the results showed that the mechanochemically activated geopolymer-stabilized soil has better resistance to sulphate erosion than the conventionally activated geopolymer-stabilized soil. The residual UCS for MAG and CAG samples were 93% and 89% when exposed to 1% magnesium sulphate solution for 60 days, whereas they declined to 70% and 58%, respectively, after 120 days of immersion.

Mechanical, physical and durability performance of engineered cementitious composites prepared with calcium aluminate cement

This research aims to fill a gap in existing studies by exploring the use of calcium aluminate cement (CAC) as an eco-friendly substitute for Ordinary Portland Cement (OPC) in Engineered Cementitious Composites (ECC). The study investigates the impact of CAC, both with and without the presence of fly ash (FA), on the mechanical, physical, durability, and microstructural properties of ECC-CAC mixtures. Various proportions of FA-to-CAC up to 1.5 were considered, while assessing different engineering parameters of compressive and flexural strengths, ductility, ultrasonic measurements, chloride penetrability, and drying shrinkage. Moreover, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX) and X-Ray diffraction (XRD) were utilized to analyze the reaction products related to CAC and/or FA in selected mixtures. Higher strengths of CAC-ECC were achieved at earlier curing ages, though the transformation of CAC’s metastable phases led to reduced strengths in ECC-CAC mixtures compared to the control ECC during extended curing periods. Furthermore, the combination of FA with CAC played a crucial role in avoiding the hydrates conversion and minimizing the shrinkage in CAC-ECC, achieving even lower shrinkage levels than those observed in control OPC-ECC.

Durability Evaluation of GGBS-RHA-Based Geopolymer Concrete Along with Lightweight Expanded Clay Aggregate Using SEM Images and EDAX Analysis

The durability of geopolymer concrete containing Ground Granulated Blast Furnace Slag (GGBS) and Rice Husk Ash (RHA), along with Lightweight Expanded Clay Aggregate (LECA), was investigated. Six different LWGPC mixtures were made with NaOH molarities of 8, 10, and 12M. For each molarity, two combinations of source materials were selected: 100% GGBS (G) and 80% GGBS with 20% RHA (RG). In all the mixtures, coarse aggregate was substituted with 35% LECA. LWGPC mixtures were exposed to 3% HCl, 5% MgSO4, and 3.5% NaCl for studying the durability properties. The test results demonstrate that 100% GGBS with 12M NaOH (12G) outperformed all other mixtures. The residual compressive strength of 12G mix LWGPC specimens after six months of exposure was found to be 86.4% in an acid environment, 90.6% in a sulfate environment, and 91.4% in a salt environment. The elemental composition analyzed using EDAX reveals that silica, alumina, calcium, and sodium are the predominant elements that form a dense microstructure with N-A-S-H, C-A-S-H, and C-S-H. Further, the inner properties of the specimens exposed to chemicals were examined using MATLAB R2023b and ImageJ 1.54f based on SEM images. The SEM image showed that the porosity of LWGPC specimens ranged from 0.5194 to 0.6748 µm, signifying an enhanced durability performance. The experimental results and microstructural analysis show that the LWGPC incorporating RHA and GGBS with LECA offers a superior performance, making it a promising solution for sustainable and durable construction.

Thin-layer Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) reinforced with small-diameter FRP bars for structural strengthening

This study proposed a novel strengthening system for reinforced concrete (RC) structures using a thin layer of Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) reinforced with small-diameter Fiber-Reinforced Polymer (FRP) bars. Experimental investigation, digital image correlation analysis, and numerical simulation were conducted to evaluate the flexural performance and failure mechanism of RC beams strengthened with 20-mm UHS-ECC layers and 3-mm FRP bars. It was found that the 20-mm UHS-ECC layer alone improved the load capacity of RC beams by 8.3 %, though with reduced deflection, whereas incorporating two 3-mm FRP bars increased load capacity by up to 40.4 %, without sacrificing deflection. Failure in all specimens was caused by concrete crushing; however, FRP-reinforced UHS-ECC layers mitigated early crack localization, significantly enhancing both strength and ductility. This study also revealed that cast-in-place FRP-reinforced UHS-ECC layers exhibited higher load capacity and could avoid ECC/concrete interfacial cracks compared to epoxy-bonded prefabricated layers. A three-dimensional finite element model was proposed for the strengthening system, and the flexural behavior was successfully predicted. It is revealed that the FRP-to-UHS-ECC bond had a marginal influence on performance, while the bond at the UHS-ECC-to-concrete interface significantly impacted flexural behavior. Remarkably, the small-diameter FRP bar achieved 75 % of its tensile strength at the ultimate stage. These findings underscore the potential of FRP-reinforced UHS-ECC layers as an effective solution for enhancing the mechanical and durability performance of RC structures.

Investigation of surface structuring and oxidation performance of Inconel 718 superalloy by laser remelting with different patterns

The current paper deals with the effect of CO2 laser remelting on the surface structuring and oxidation performance of Inconel 718 superalloy, pointing out different laser-induced surface patterns that make a difference in their oxidation properties vital for high-temperature applications. Surface roughness, microstructure, and oxidation behavior characterization were performed using 3D optical profilometry, SEM, and XRD techniques. The oxidation tests conducted at 1000 °C for 24 h have revealed that remelted surfaces offered better oxidation resistance compared to untreated samples. Notably, the patterned sample showed the lowest weight gain under oxidation, and a parabolic regime in oxidation occurred after 100 min; while in an untreated reference sample, this appears only after 200 min. This improvement in performance results from the formation of a chromium-rich oxide layer on the melt pools, which acts as an effective barrier against further oxidation. The findings show that laser remelting, especially with grid-like surface patterns, results in an improvement in both durability and high-temperature performance of Inconel 718; therefore, it is apparently a very promising technique for lifespan extension of industrially relevant materials.

Accelerated environmental conditions study on palm oil fuel ash-incorporated engineered cementitious composites: A durability assessment approach

This study investigated the durability performance of Engineered Cementitious Composites (ECC) containing varying amounts of palm oil fuel ash (POFA) under accelerated environmental conditions. The research employed three distinct water-binder (cement + POFA) ratios (w/b) of 0.33, 0.36, and 0.38, along with POFA proportions ranging from 0 % to 1.2 % by mass of cement (POFA/C). Furthermore, ECC bars were immersed in 1 M NaOH at 80°C, with expansion and alkali-silica reaction monitored for 30 days. To examine the NaCl effect, ECC coupon specimens were first preloaded under four-point bending at 1.5 mm displacement, then exposed to a 3 % NaCl solution for 30 and 60 days, and then reloaded up to failure. The RCPT was performed at 28, and 90 days, per ASTM C1202 standard, by measuring the electrical current through a 50 mm thick, 100 mm diameter sample over 6 hrs. The results show that higher w/b ratios increased ASR-induced expansion in ECC bars, but higher POFA content mitigated this. ECC with 1.2 POFA/C at 0.33 w/b had the highest 0.1 % expansion at 30 days, within ASTM limits. The POFA-ECC specimens also exhibited enhanced chloride penetration resistance as POFA content increased, with the 1.2 POFA/C and w/b 0.33 specimens showing 61–71 % reductions in total charge passed at 28–90 days. Mechanically pre-loaded POFA-ECC remained durable when exposed to chloride. Additionally, POFA-ECC demonstrated self-healing of micro-cracks, allowing them to sustain significant flexural load capacity. These findings highlight the potential of POFA as a supplementary cementitious material in ECC, providing improved chloride resistance while preserving structural integrity.

Ginger powder as sustainable and eco-friendly corrosion inhibitor for the protection of steel reinforcement bars

In the present studies, ginger powder has been used as an eco-friendly admixture for the cement mortar. Different amounts i.e. 0 wt% (M1), 0.10 wt% (M2), 0.25 wt% (M3) and 0.50 wt% (M4) ginger powder was mixed in the cement mortar (M1) and assessed the durability. The ginger powder with 0.50 wt% (M4) improves the compressive strength by 17 % owing to the water reducing capability, which enhance the hydration reaction and fill the pore matrix of the cement mortar. The active ingredient of ginger powder i.e. shogaol adsorbs on the steel rebar surface through leaching mechanism by interaction of oxygen (O) and п-electrons with iron (Fe) and provide corrosion protection at longer duration of continuous immersion in 3.5 wt% NaCl solution. Following 173 d in a 3.5 wt% NaCl solution, the M4 sample exhibits 82.10 % corrosion inhibition efficiency. Therefore, it is suggested that ginger powder could be a potential eco-friendly admixture to be used in construction industries to get high durability performance in the coastal areas.

Experimental study on the influence of different curing methods on the performance of concrete

Curing concrete is an effective method to ensure concrete’s mechanical and durability performance. This article experimentally investigates the impact of various curing methods (air curing, sprinkler curing, geotextile curing, and composite geotextile curing) on the compressive strength of concrete at 7, 14, and 28 days, as well as the carbonation depth and chloride ion diffusion coefficient at 28, 56, and 90 days. The effects of different curing methods on concrete performance are compared. The experimental results demonstrate that sprinkler, geotextile, and composite geotextile curing at 7 and 14 days effectively enhance concrete’s mechanical and durability performance. Compared to air curing concrete at 28 days, sprinkler, geotextile, and composite geotextile curing reduced by 17.75 %, 25.11 %, and 31.51 %, respectively, but the average absolute deviation is reducing. From 28 to 90 days, air curing concrete’s chloride ion diffusion coefficient decreases by 8.5 %. For concrete specimens under sprinkler curing, geotextile curing, and composite geotextile curing, the chloride ion diffusion coefficient decreases by 20.4 %, 8.3 %, and 6.0 %, respectively. Beyond 28 days, the durability performance of concrete under composite geotextile curing, including carbonation depth and chloride ion diffusion coefficient, tends to stabilize. The optimal curing period of 28 days is determined based on comprehensive mechanical and durability performance. Composite geotextile curing retains moisture on the concrete surface, slows evaporation, reduces watering frequency and labour costs, and promotes long-term concrete performance development. Carbonation tests and durability performance, such as chloride ion diffusion coefficient, are more sensitive to concrete curing effects. Single indicators like mechanical or durability performance cannot comprehensively evaluate concrete’s long-term performance. Concrete quality should be comprehensively evaluated by considering strength, carbonation depth, chloride ion diffusion coefficient, and other indicators.

Developing greener concretes from spent bleaching earth and sugarcane bagasse ash

Concrete is by far the most widely utilized construction material due to its excellent mechanical and durability properties. However, the concrete industries are notorious for their anthropogenic activities that contribute to climate change. Cement production alone consumes immense amounts of energy and trails a significant CO2 footprint. One solution that researchers have deemed promising over the last couple of decades is the substitution of cement with agricultural waste products, which subsequently serves to alleviate waste disposal problems. This study investigates the suitability of spent bleaching earth (SBE) and sugarcane bagasse ash (SCBA) as partial replacement of ordinary Portland cement (OPC) in increments of 0, 5, 10 and 15% by mass. Tests were conducted in accordance to British Standards to assess the consistence, compressive strength, split tensile strength and drying shrinkage strain of SBE and SCBA based concretes. Results indicated that while these concretes displayed similar degrees of consistency, the SCBA concretes exhibited superior compressive and tensile strengths. Optimum SCBA dosages were revealed to be about 5-10%, yielding a 7-12% and 3-8% increase in compressive and tensile strengths, respectively, as compared to OPC concrete. Drying shrinkage behavior was also improved in the SCBA concretes. Further, comparisons of the mechanical and durability performances of the concretes with British and American codes suggest that up to 10% replacement of cement with SCBA may be a viable approach to developing sustainable materials for the concrete industry.

Development and assessment of eco- and user-friendly geopolymeric stabilizers for sustainable soil improvement

This paper presents an innovative approach to address inherent limitations in traditional geopolymerization methods by focusing on producing eco and user-friendly mechano-chemically activated geopolymeric (M-GP) stabilizers for soil stabilization applications. A comparative analysis is conducted to benchmark the effectiveness of these stabilizers against conventionally activated geopolymer (C-GP) stabilizers. The study also investigates the influence of ground granulated blast furnace slag (GGBFS) amount on the mechanical and durability characteristics of stabilized soil specimens. Furthermore, the effect of activation techniques on the efficacy and strength of soil after sulfuric acid (H2SO4) exposure was investigated. The durability performance was evaluated by submerging the samples in a 1 % H2SO4 solution for a period of 60 and 120 days. The evaluation addresses various aspects such as visual appearance, mass changes, unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV) and the Fourier transform infrared spectroscopy (FTIR) of geopolymer-stabilized soil samples. Results indicate that the UCS of M-GP samples surpassed C-GP-stabilized soil by 12–45 %. Moreover, the geopolymer-stabilized soil exhibited a significant increase in strength, with improvements of 114 %, 247 %, and 361 % observed at GGBFS content levels of 50 %, 75 %, and 100 % by weight, respectively. After exposure to the H2SO4 solution, M-GP-stabilized soil demonstrated superior resistance to sulfuric acid compared to C-GP-stabilized soil. The residual ultimate compressive strength (UCS) for M-GP and C-GP specimens was 80 % and 76 % respectively after being subjected to the H2SO4 solution for 60 days. However, these values further declined to 53 % and 48 % after 120 days of exposure. In addition, the result showed that geopolymer-stabilized soil containing 75 % slag exhibited superior resistance to H2SO4 compared to other stabilized soil samples.

Influence of polypropylene fibers on the tensile mechanical properties of calcium silicate hydrate: molecular simulation.

This research assesses the influence of polypropylene (PP) fibers, both homopolymer and hydroxylated (PPOH), on the tensile properties of calcium silicate hydrate (C-S-H) composites through molecular dynamics (MD) simulations. Our models explore C-S-H matrices integrated with PP and PPOH fibers at varying polymerization degrees. The results demonstrate that both PP and PPOH fibers significantly influence the tensile strength and Young's modulus of the composites. Notably, PPOH fibers contribute to more substantial mechanical enhancements than PP, attributed to the increased polarity and enhanced intermolecular interactions from the hydroxyl groups. The study reveals a nonlinear relationship between polymer additive content and mechanical performance, with optimal properties at a polymerization degree of 20. Additionally, stress-strain analysis indicates that PPOH composites exhibit superior ductility and fracture energy, particularly at polymerization degrees of 20, showing enhanced ultimate strain and fracture energy by up to 9.6% and 13.9%, respectively, compared to PP counterparts. These results highlight the crucial role of tailored polymer additive composition and chemical modifications in maximizing the mechanical efficacy of C-S-H-based materials, enhancing their durability and structural performance. All MD simulations were conducted using LAMMPS. The models employed a combination of Clayff and Cvff force fields. During the entire tensile simulation, the system was configured under the NPT ensemble at 300K.

High-Strength Self-Compacting Concrete Production Incorporating Supplementary Cementitious Materials: Experimental Evaluations and Machine Learning Modelling

AbstractThis study investigates mechanical properties, durability performance, non-destructive testing (NDT) characteristics, environmental impact evaluation, and advanced machine learning (ML) modelling techniques employed in the analysis of high-strength self-compacting concrete (HSSCC) incorporating varying supplementary cementitious materials (SCMs) to develop sustainable building construction. The findings from the fresh characteristics test indicate that mixes’ optimal flowability and passing qualities can be achieved using different concentrations of marble powder (MP) alongside a consistent amount of silica fume (SF) and fly ash (FA). Moreover, the incorporation of 10% MP along with 10% FA and 20% SF in HSSCC significantly improved the compressive strength by 14.68%, while the splitting tensile strength increased by 15.59% compared to the reference mix at 56 days. While random forest (RF), gradient boosting (GB), and their ensemble models exhibit strong coefficient correlation (R2) values, the GB model demonstrates more precision, indicating reliable predicted outcomes of the mechanical properties. Following subsequent testing, it has been demonstrated that incorporating SCMs improves the NDT properties of HSSCC and enhances its durability. The finer MP, SF, and FA particles enhanced microstructural performance by minimizing voids and cracks while improving the C–H–S bond. As noticed by its lower CO2-eq per MPa for SCMs, the HSSCC mix with up to 15% MP inclusion increased mechanical strength while reducing the environmental footprint, making it an eco-friendly concrete alternative.

Robust photothermal anti/de-icing hydrophobic coating based on polydopamine (PDA) composition

The hydrophobic soft coating has low ice adhesion strength and hydrophobic stability in low-temperature and high-humidity environments, which is crucial for preventing ice formation on infrastructure and transportation systems. However, creating mechanically durable hydrophobic soft coatings using simple methods remains challenging. In this study, a high-hardness particle-toughened, self-stratifying organic layer with high photothermal conversion rate was developed to enhance coating durability and ice-repellent performance. By optimizing the ratio of dopamine (DA) and sodium alginate (SA), a hydrophobic photothermal agent (DPSn) with high hardness and a significant light-heat effect was synthesized. A durable, hydrophobic photothermal anti-ice coating (AR/20 %PDMS/x%DPS1) with varying DPS1 amounts was successfully created using a straightforward one-step spray method, utilizing the self-stratification characteristics of acrylic resin (AR) and polydimethylsiloxane (PDMS), along with the toughening effect of DPSn. The fiber cross-linked structure of DPS1 achieved a photothermal conversion rate of 87.5 %. Adding 4 wt% DPS1 increased the surface temperature of the AR/20 %PDMS coating to 96.5 ± 2.4 °C and boosted the coating’s adhesion strength from 6.70 ± 0.3 MPa to 7.23 ± 0.7 MPa. The AR/20 %PDMS/4%DPS1 coating demonstrated excellent anti-/de-icing performance after 60 friction cycles, 60 icing/de-icing cycles, and 132 h of acid-base immersion. Its simple preparation process and durable ice-repellent properties make it highly suitable for practical applications in photothermal hydrophobic soft coatings.