Flexural Strength Research Articles

Towards improved flexural behavior of plastic-based mortars: An experimental and modeling study on waste material incorporation

A considerable fraction of solid waste, which is harmful, chemically reactive, and infectious, is generated globally. The frequent deposition of these wastes in landfills has significant environmental and health consequences. This study aims to develop an environmentally conscious approach by incorporating finely ground waste materials, namely marble powder (MP), glass powder (GP), and silica fume (SF), into plastic waste (PW) based mortar to assess their efficacy in improving flexural strength (FS). Plastic waste mortar samples were cast using shredded PW, replacing sand in amounts ranging from 5% to 25%. The FS of these samples was measured after 28 days and used as a reference. MP, GP, and SF were individually incorporated into PW-based mortar formulations in varying quantities of 5-25%, with increments of 5%, by replacing cement. In PW-based mortar formulations, waste materials were also utilized in various combinations, including GP+SF, MP+SF, MP+GP, and MP+GP+SF. In addition, prediction models, including decision tree (DT) and artificial neural network (ANN), were constructed utilizing experimental data for the FS of PW-based mortar. The substitution of PW with sand reduces the FS of mortar samples. The research findings emphasize that optimal replacement levels for MP, GP, and SF in PW-based mortar mixtures, based on their ability to enhance FS, were 15%, 10%, and 15% by cement mass, respectively. However, the cumulative incorporation of MP, GP, and SF in PW-based mortar suggests cement should not be replaced beyond 15%, as it reduces the FS. Both prediction models exhibited a high degree of correlation with the coefficient of determination (R2) value of 0.925 for ANN and 0.959 for the DT model. The findings showed that MP, GP, and SF may be used in PW-based mortar to improve the FS while producing eco-friendly building material.

Comparative analysis of mechanical properties of SiC particle addition on Al6061/Ni and Al6061/Cr metal matrix composites

This research paper investigates the mechanical characteristics of Al6061/Nickel (Ni) and Al6061/Chromium (Cr) metal matrix composites (MMCs) with varying proportions of Ni and Cr by weight. The proportions of Ni and Cr range from 0% to 2.7% weight. Experimental results reveal that the optimum mechanical properties are achieved at 1.8% weight for Ni. Subsequently, SiC (silicon carbide) particles are added to Al6061/Ni MMCs at varying weight percentages (0%, 1%, 3%, 5%, and 7%) to evaluate their impact on performance. The study demonstrates that the combination of 1.8% Ni and 7% SiC in Al6061 exhibits the most favorable properties. Tensile test is carried out with ASTM D 3552 standard; Flexural strength is assessed through ASTM D790, Microhardness by ASTM E384, and Impact strength by ASTM D256. Overall, Al6061/Ni MMCs exhibit superior mechanical performance compared to Al6061/Cr MMCs, with Al6061/Cr MMCs excelling in elongation, flexural strength, and impact strength. This investigation confirms that the addition of nickel and chromium to the Al6061 alloy induces structural modifications that enhance its mechanical properties. The findings provide valuable insights for optimizing the design and fabrication of MMCs for various engineering applications.

Design and Fabrication of Banana Fiber Reinforced Bio Composite

Abstract: This study explores the mechanical properties and potential applications of banana fiber-epoxy resin composites fabricated with an 80% resin and 20% fiber ratio using a hand layup method. The composites were comprehensively tested for tensile strength, flexural strength, impact resistance, and compression strength to assess their performance characteristics. The results highlight the effectiveness of banana fiber as a reinforcement material in epoxy composites, demonstrating promising mechanical performance suitable for structural and load-bearing applications in industries such as automotive, construction, and aerospace. The composites exhibited notable advantages, including enhanced tensile and flexural strength, good impact resistance, and high compression strength, making them viable alternatives to traditional composite materials. The sustainable nature of banana fiber further contributes to the eco-friendliness of these composites. This research emphasizes the potential of banana fiber-epoxy resin composites to develop sustainable and high-performance materials, paving the way for innovative applications in various sectors. The findings contribute valuable insights into utilizing natural fibers like banana fiber in epoxy resin matrices to enhance composite properties and promote the adoption of eco-friendly material solutions in modern industries

Enhancing structural analysis and electromagnetic shielding in carbon foam composites with applications in concrete integrating XGBoost machine learning, carbon nanotubes, and montmorillonite

Electromagnetic shielding in carbon foam composites involves using the natural conductivity of carbon foam to block or absorb electromagnetic fields. These composites protect sensitive electronic devices from electromagnetic interference (EMI), which can disrupt or damage their operation. The inclusion of XGBoost machine learning analyzes and optimizes the material compositions for electromagnetic interference shielding. By integrating Carbon Nanotubes (CNTs) and Montmorillonite (MMT) into samples of carbon foam, this research aims to identify the electromagnetic shielding effectiveness (SE), electrical conductivity, and dielectric permittivity at different frequencies of carbon foam composites. This analysis will facilitate the development of enhanced composite materials tailored for effective EMI shielding in concrete environments, particularly in structures housing sensitive electronic equipment. The novelty of this study lies in the dual integration of carbon nanotubes and montmorillonite into carbon foam composites, uniquely exploring their synergistic effects on both mechanical and electrical properties. The study employs XGBoost machine learning to optimize the material compositions for enhanced electromagnetic interference shielding. This study probes the dual integration of CNTs and montmorillonite into carbon foam composites, evaluating their synergistic impact on mechanical and electromagnetic properties. Incorporating 1 %, 3 %, and 5 % of these additives into carbon foams, substantial improvements were recorded in compressive, tensile, and flexural strengths, peaking with a 5 % MMT enhancement that nearly doubled the compressive strength from 3.96 MPa to 9.44 MPa. Concurrently, these composites displayed enhanced EMI SE, with detailed electrical characterizations at varying frequencies. Employing XGBoost machine learning, optimal material compositions were derived for EMI shielding, presenting advancements for industrial applications requiring robust structural and electrical performance.

Influence of surface finishing on the outcome of a 3-point bending test in polymer-based dental composits assessed by qualitative and quantitative fractography

ObjectivesThe aim of the study was to evaluate the influence of surface finishing in three polymer-based composits (composits) on the result of a 3-point bending test using quantitative and qualitative fractography as well as microstructural characteristics. Materials and methods270 rectangular specimens (n = 30) of three composits were prepared, stored and tested according to NIST No. 4877. Prior testing, the samples were subjected to three surface treatments: 1) no treatment, to preserve the oxygen inhibition layer, 2) with FEPA P1200 (ANSI equivalent grit 600) SiC paper abraded surface, and 3) polished surface. A three-point bending testing was employed, followed by quantitative (assessment of reason for failure and fracture pattern) and qualitative (fracture mirror measurements) fractography, 3D and 2D surface imaging, surface roughness, reliability and Fe-SEM analysis. The mirror radius that runs in the direction of constant stress was used to calculate the mirror constant (A) using Orr's equation. Uni- and multifactorial ANOVA, Tukey's post hoc test, and Weibull analysis was performed for statistical analysis. ResultsSurface finishing has less influence on the fracture pattern, reliability and mechanical parameters and has no influence on the mirror constant. The amount of inorganic filler has a direct impact on flexural strength and modulus, while the ranking of materials was independent of surface treatment. Failures initiated by volume defects were the most common failure mode (77.0%) with surface defects accounting for 14.9% (edge) and 7.7% (corner). Polishing resulted in lower peak-to valley height compared to no treatment, both 3–4 times lower compared to the 600 grit treatment. The increase in roughness within the analyzed range did not lead to an increase in surface-related failures. ConclusionsThe clear dominance of volume defects in all examined materials as a cause of material fracture reduces the impact of roughness on the measured properties. This insight was only possible using qualitative and quantitative research fractography.

An Experimental Study of Strength Properties of Galvanized Iron (GI) Fiber Reinforced Concrete

Abstract: Fiber Reinforced Concrete is one of the most quality construction techniques of modern times. The utilization of locally available galvanized iron or metallic fiber as a bridging material. The concrete with metallic or nonmetallic fiber is very useful and its enhanced concrete mechanical properties. Therefore, a research has been conducted to study the performance of locally available GI wire fiber reinforced concrete (GWRC). This paper presents the findings of the research that made an effort to explore several basic characteristics of GWRC primarily related to strength, ductility and durability. This research was, therefore, conducted to compare the concrete strength performance of GI fiber with different lengths and a control specimen. The objective of this study is to explore the effect of GI fiber in terms of compressive strength, splitting tensile strength, and flexural strength with ‘Galvanized Iron’ fiber using several cutting lengths of 25 mm and 35mm with various mix proportions including 1.0%, 1.5%, 2.0%, and 2.5% by weight of the concrete

Thermal – chemical - mechanical characterization of Anacardium occidentale tree gum

Anacardium occidentale (cashew) tree gum is being used in several sectors, including the pharmaceutical sector. This gum has been explored more in the medical field by many previous researchers, but there is a big research gap regarding its thermal and mechanical properties. Therefore, this research is intended to reveal the thermal, chemical, and mechanical characteristics of Anacardium occidentale tree gum. The results obtained in this regard are then compared with certain properties of artificial resins. Thermal analysis is carried out using a thermogravimetric analyzer, and differential scanning calorimeter, elemental analysis is carried out using a scanning electron microscope and a micro-X-ray fluorescence analyzer; and mechanical tests are carried out using a nano-indentation tester and a universal testing machine. The pH of 4.76 shows that the gum is acidic in nature, and the peaks obtained from thermal analysis demonstrate that it doesn't have a melting point. The microhardness value, tensile strength, flexural strength, and compressive strength of cashew gum are 218.39 MPa, 1.667 MPa, 3.64 MPa, and 2.667 MPa, respectively. The obtained results show that, Anacardium occidentale tree gum has comparable thermal properties to those of artificial resins and other natural gums.

Determination of Mechanical Properties of Hybrid Composite

Abstract: Manufacturing of composite laminates is the peculiar member of science that encounter its immense utilization in various industrial areas such as sporting, automotive, aerospace and marine industries. The superior properties of composites such as stiffness, better mechanical properties, low density, and lightweight make it a candidate in engineering applications. The continuous research in this area is due to the need for seeking alternative materials with increased performance. In this report, the basalt fiber E-glass reinforced composite mechanical properties has investigated. The basalt fiber E-glass composite was formulated with hand layup moulding technique. Mechanical properties such as tensile, flexural strength and impact strength of the basalt fiber E-glass composite have been analysed

Study on static and dynamic mechanical properties and microstructure of silica fume-polypropylene fiber modified rubber concrete

Through tests and micro-observations, the static and dynamic mechanical properties and microstructure of rubber concrete samples modified with varying amounts of silica fume and polypropylene fiber content were explored. The results indicate that incorporation of silica fume and polypropylene fiber can effectively enhance the performance of rubber concrete. Moreover, at 10% and 0.1% of silica fume and polypropylene fiber content respectively, rubber concrete’s compressive strength, splitting tensile strength, flexural strength, and dynamic compressive strength reached maxima. Furthermore, microstructure characteristic analysis indicated that inadequate adhesion between rubber particles and the matrix is responsible for compromised bearing capacity in unmodified rubber concrete. However, with the addition of silica fume and polypropylene fiber, the fiber binds the rubber particles closely with the matrix, while the silica fume fills the gaps between the matrix components. This combination results in rubber concrete with a denser internal structure and enhances its bearing capacity significantly.

Well-designed flame retardants for epoxy resin composites that simultaneously improve heat resistance, mechanical properties and fire safety

Epoxy resin (EP) flammability severely limits its application in some industrial fields, while flame retardant epoxy resin (FREP) often suffers from the problem of not being able to balance flame retardant properties with mechanical properties. To solve the problem, in this work, HDP, a reactive flame retardant was succeeded in synthesizing by the one-pot method using protocatechuic aldehyde (PH), 2,4-diamino-6-phenyl-1,3,5-triazine (DPT), and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as reactive monomers, was used to improve the flame retardancy of EP. And evaluated the effect of HDP on the curing reaction, heat resistance and mechanical property of EP. The introduced of four phenolic hydroxyl groups and two secondary amine groups enhanced the compatibility of the flame retardant HDP in EP and improved process performance. The apparent activation energy (Ec) was reduced by 8.1 %, facilitating the curing of EP/DDM. When 5 wt% of HDP (with only 0.36 wt% phosphorus content) was added to EP, the flexural strength and modulus of FREP increased by 21.0 % and 14.9 %, respectively, and the Tg increased by 9.0 % compared to EP. Cone calorimeter test (CCT) data showed that compared to EP, samples of EP/HDP-5 showed a 14.5 % and 21.6 % reduction in total heat release (THR) and total smoke production (TSP), respectively, and a 13.7 % increase in coke yield (CY). EP/HDP-5 has a high limited oxygen index (32.5 %) and passes the UL-94 V-0 classification. The excellent char formation and flame retardancy was owed to the dual role of the condensed and gas phases of FREP in the combustion process.

Experimental Investigation of Partial Replacement of Cement in Concrete using Waste Glass Powder

Abstract: The construction industry is the second largest industry in the world & concrete is prime material used in it [5]. The use of concrete generates lots of heat during hydration process. It directly contributes to global warming. Also cement is costly material & its storage is also difficult. The cement plays important role of binding in concrete. It contains lime as main constituents. So to reduce this ill effect of cement one must find the alternatives for cement which can perform the same role in concrete. This study represents the experimental investigation of effect of partial replacement of cement by glass powder on strength of concrete & other factors like workability, water cement ratio, and heat of hydration. Glass contains lime as its one of main constituent. The cement was replaced with glass powder by 5%, 10%, 15%, and 20%. The compressive strength, flexural strength & split tensile strength are tested for these replacements. Also economical aspect is observed along with. It is observed that physical & chemical properties of glass are almost similar to cement. So in this study an attempt is made to investigate the effect of partial replacement of cement by glass powder in concrete to make it as a special concrete

Strength Evaluation of Concrete using Over burnt Brick Stone as Replacement of Coarse Aggregate

Abstract: This research highlights on the behavior of concrete, prepared by the partial replacement of regular aggregate with over-burnt brick aggregate (jhama brick) with a replacing percentages of 0% , 35, 50% & 60% over M20 Grade of concrete which reduces the cost of aggregate (upto 30%) with higher strength, which also results in overall cost in building too .The effect of compressive strength, split tensile strength and flexural strength were reported . The received compaction factor is 0.92, 0.89, 0.88, and 0.87 with varying percentage of (0%, 35%, 50%, 60%) Jhama class brick respectively. This research was conducted to study the suitability crushed over burnt bricks as alternative course aggregates for concrete production. The compressive strength of this concrete is found to be 27.12 , 30.41, 26.02, 23.31 for 0%, 35%, 50%, 60% respectively. The concrete cube, beams and cylinders of M-20 grade were thrown in this trail, explore work and try to analyze different properties of concrete with crushed over burnt bricks as an alternative material. The result shows that the aggregate in concrete derived from Over Burnt bricks aggregate attained relatively higher strength upto the certain percentage and decreases after that, than the regular concrete. More detailed and elaborated work is recommended with different mix ratio and a different proportion of Over Burnt aggregates for a better conclusion.

Strong, anti-swelling, and biodegradable seaweed-based straws with surface mineralized CaCO3 armor

While the extensive utilization of disposable plastic straws has resulted in significant environmental issues such as microplastics and soil and ocean pollution, the quest for alternative straws for versatile use remains a formidable challenge. Here, drawing inspiration from naturally water-resistant materials such as bones and sea urchins, we have developed seaweed-based straws with significantly improved water resistance and mechanical strength via in-situ mineralization of CaCO3 on their surfaces. Specifically, the COO− groups on the G (α-L-guluronate) blocks of alginate were employed to establish a robust cross-linked network, while the COO− groups on the M (β-D-mannuronate) blocks attracted free Ca2+ through electrostatic forces, thereby promoting CaCO3 nucleation. This effectively prevents COOH groups from hydrating, reducing swelling, and results in the fabrication of nano- to micron-sized CaCO3 particles that reinforce the structure without compromising the cross-linked network. Compared with the control group, the S5% sample (prepared with 5 % Na2CO3 solution) exhibited a 102 % increase in water contact angle, a 35 % decrease in swelling degree, and a 35.5 % and 37.5 % increase in ultimate flexural and tensile stress, respectively. Furthermore, the potential use of these straws as a waste for heavy metal adsorption was investigated, addressing environmental concerns while demonstrating economic feasibility.

Investigation of Mechanical Properties of Natural Fiber Reinforced Hybrid Composite

Abstract: Hybrid composite is a material composed of matrix and two or more reinforcements. Two or more reinforcements in hybrid composite replace the limitation of conventional composites by providing uniform strength to thematerial. Recently, natural fibers reinforced hybrid composites are gaining increased interest due to the encouraging properties of natural fibers such as high strength to weight ratio, low cost, no harm to environment etc. Many studies dealt with natural fibers based composite reported that the hybrid composites has the potential to replace glass fiber based composites and to reduce the weight of conventional composite. This project reports on the manufacturing of the Indian elm and Acacia fibre reinforced epoxy composite laminate as per the ASTM (American Society for Testing and Materials) Standards. This laminate consists of matrix and reinforcement. Epoxy is used as a structural matrix material which is then reinforced by Indian elm fiber, combining Acacia fibres with resin matrix results in composites that are strong, lightweight, corrosion-resistant and dimensionally stable. They also provide good design flexibility, high dielectric strength and act as inflammable materials. Their tremendous strength-to-weight and design flexibility make them ideal in structural components for the aerospace industry. In this project the Indian elm and Acacia fibre reinforced epoxy composite is manufactured into two different parts each having ratios of Indian elm and Acacia fibre to epoxy resin as 60:40, 40:60 respectively and are compared for ultimate tensile strength, impact strength, hardness strength and flexural strength of the material by conducting experiment such as tensile test, flexural test, hardness test and impact test.

An Experimental Investigation on Mechanical Properties of Bacterial Concrete Using Bacillus Subtilis

Abstract: This Concrete is susceptible to micro crack formation and has pores which are highly undesirable because they provide an open pathway for the ingress of water and other deleterious substances. The use of concrete surface treatments with water proofing materials to prevent the access of aggressive substances is a common way of contributing to concrete durability. However, the most common surface treatments use organic polymers (epoxy, acrylics and polyurethanes) all of which have some degree of toxicity. Bio inspired materials can lead to a more sustainable construction industry, especially when providing new low toxic solutions. Hence, there is an urgent need to pay more attention for improving the properties of concrete with respect to strength and durability, especially in aggressive environments. One effective remedy for closure of cracks is the Bacterial Concrete (BC) which will continuously deposit calcite in concrete. This, phenomenon is called as Microbiologically Induced Calcite Precipitation (MICP). The urease enzyme enables the deposition of calcium carbonate (CaCO3) with the help of bacteria. The bacterial remediation technique surpasses other techniques as it is bio-based, eco-friendly and durable. Bacteria need to offer resistance to withstand high pH of concrete and mechanical stresses during mixing. In these present investigations bacterial sample name Bacillus Subtilis (BS) is considered in concentrations of 104 , 105 and 106 cells/ml of mixing of water. investigations are carried out on strength-related properties such as compressive strength, splitting tensile strength and flexural strength to assess the quality of concrete. The optimum dosage of cell concentration of bacteria is found to be 105 cells/ml for BS based on compressive strength results. M25 grade concrete is designed and used for embedding Bacillus subtilis bacteria.

Analysing the shape memory behaviour of GnP-enhanced nanocomposites: a comparative study between experimental and finite element analysis

Shape memory polymers (SMPs) are capable of enduring significant deformations and returning to their original form upon activation by certain external stimuli. However, their restricted mechanical and thermal capabilities have limited their broader application in engineering fields. To address this, the integration of graphene nanoplatelets (GnPs) with SMPs has proven effective in enhancing their mechanical and thermal properties while maintaining inherent shape memory functions. The study evaluated shape memory nanocomposites (SMNCs) using dynamic mechanical, thermogravimetric, and static tensile, flexural, and shape memory tests, along with scanning electron microscopy to analyse tensile fractures. The results indicate that the optimal content of GnP is 0.6 wt%, resulting in excellent shape memory, thermal, and mechanical properties. Specifically, this composition demonstrates a shape recovery ratio of 94.02%, a storage modulus of 4580.07 MPa, a tensile strength of 61.42 MPa, and a flexural strength of 116.37 MPa. Additionally, the incorporation of GnPs into epoxy reduces recovery times by up to 52% at the 0.6 wt% concentration. While there is a slight decrease in the shape fixity ratio from 98.77% to 93.02%, the shape recoverability remains consistently high across all samples. Current finite element (FE) models often necessitate complex, problem-specific user subroutines, which can impede the straightforward application of research findings in real-world settings. To address this, the current study introduces an innovative finite element simulation method using the widely used ABAQUS software to model the thermomechanical behaviour of SMNCs, importantly incorporating the time-dependent viscoelastic behaviour of the material. The effectiveness of this new approach was tested by comparing experimental results from bending test of SMNCs cantilever beam with outcomes derived from FE simulations. The strong agreement between the experimental data and simulation results confirmed the precision and reliability of this novel technique.

Preparation and characterization of polyurethane composite modified epoxy resin for novel colored anti-skid pavement materials

To develop a bonding material suitable for colored anti-skid road surfaces, this study prepared a composite modified epoxy resin by modifying epoxy resin with polyurethane, nano-SiO2, and diluent 669. The mechanical properties of the composite modified epoxy resin were evaluated through tensile and bending tests. The results indicate that the tensile strength and bending strength of the composite modified epoxy resin increased by 6.23 % and 23.96 %, respectively, compared to pure epoxy resin. The elongation at break and bending deformation were enhanced by 94.6 % and 8 mm, respectively, compared to pure epoxy resin. The modified epoxy resin exhibited increased toughness and improved strength after modification. Thermal gravimetric analysis demonstrated that the thermal stability of the composite modified epoxy resin was superior, with a decomposition temperature 21 °C higher than that of pure epoxy resin. Through infrared spectroscopy and SEM analysis, it was revealed that during the modification process, polyurethane was chemically grafted onto the epoxy resin, while nano-SiO2 and diluent 669 contributed to physical modification of the epoxy resin.

Carbon nanotube as a conductive rheological modifier for carbon fiber-reinforced epoxy 3D printing inks

Rheological modifiers enable direct ink writing of polymers with low viscosity such as epoxy without requiring light or heat. Modifiers that conduct electrons and phonons impart multifunctional properties to 3D printed polymers. Here, we report the development of printable nanocomposite inks comprised of epoxy, carbon fibers (CFs), and carbon nanotubes (CNTs) to achieve excellent mechanical properties and multifunctionality via high electrical conductivity required for next-generation light weight aerospace, electronics, and energy applications. CF and CNT concentrations of 8.5 and 1.7 wt%, respectively, render the material shear-thinning with a high yield stress, hence printable and self-supporting after being printed. An average electrical conductivity of 10−2 S/cm and thermal conductivity of 0.3 W/m.K were measured for the 3D-printed multi-layer structures. Furthermore, tensile modulus, tensile strength, flexural modulus, and flexural strength were measured to be 5.8, 0.08, 6.0, and 0.1 GPa, respectively. Compared with other 3D printed conductive polymer nanocomposites with reported electrical conductivity and elastic modulus, the structures here have the highest specific elastic modulus. They also possess the highest electrical conductivity among the 3D printed polymeric composites of carbon nanomaterials with an elastic modulus above 1 GPa. This is due to the outstanding combination of CNTs, CFs, and epoxy. The results expand the range of polymer properties for multifunctional applications.

Evaluating mechanical and surface properties of zirconia-containing composites: 3D printing, subtractive, and layering techniques

This study assessed the monotonic and fatigue flexural strength (FS), elastic modulus (E), and surface characteristics of a 3D printed zirconia-containing resin composite compared to subtractive and conventional layering methods. Specimens, including discs (n = 15; Ø = 15 mm × 1.2 mm) and bars (n = 15; 14 × 4 × 1.2 mm), were prepared and categorized into three groups: 3D printing (3D printing – PriZma 3D Bio Crown, Makertech), Subtractive (Lava Ultimate blocks, 3M), and Layering (Filtek Z350 XT, 3M). Monotonic tests were performed on the discs using a piston-on-three-balls setup, while fatigue tests employed similar parameters with a frequency of 10 Hz, initial stress at 20 MPa, and stress increments every 5000 cycles. The E was determined through three-point-bending test using bars. Surface roughness, fractographic, and topographic analyses were conducted. Statistical analyses included One-way ANOVA for monotonic FS and roughness, Kruskal-Wallis for E, and Kaplan-Meier with post-hoc Mantel-Cox and Weibull analysis for fatigue strength. Results revealed higher monotonic strength in the Subtractive group compared to 3D printing (p = 0.02) and Layering (p = 0.04), while 3D Printing and Layering exhibited similarities (p = 0.88). Fatigue data indicated significant differences across all groups (3D Printing < Layering < Subtractive; p = 0.00 and p = 0.04, respectively). Mechanical reliability was comparable across groups. 3D printing and Subtractive demonstrated similar E, both surpassing Layering. Moreover, 3D printing exhibited higher surface roughness than Subtractive and Layering (p < 0.05). Fractographic analysis indicated that fractures initiated at surface defects located in the area subjected to tensile stress concentration. A porous surface was observed in the 3D Printing group and a more compact surface in Subtractive and Layering methods. This study distinguishes the unique properties of 3D printed resin when compared to conventional layering and subtractive methods for resin-based materials. 3D printed shows comparable monotonic strength to layering but lags behind in fatigue strength, with subtractive resin demonstrating superior performance. Both 3D printed and subtractive exhibit similar elastic moduli, surpassing layering. However, 3D printed resin displays higher surface roughness compared to subtractive and layering methods. The study suggests a need for improvement in the mechanical performance of 3D printed material.

Advancing infrastructure resilience: A polymeric composite reinforcement grid with self-sensing and self-heating capabilities

In this study, a novel multifunctional grid-shaped polymeric composite (MGPC) with reinforcing, autonomous strain, stress, and damage sensing and localizing in addition to targeted heating capabilities, has been developed. Distinct from preceding composites, this grid synthesizes these features collectively for the first time and concurrently addresses current challenges in multifunctional composites, such as environmental impact, data reliability, complexity, and production costs. The fabrication process entails 3D printing an electrical circuit with conductive filaments within a polylactic acid (PLA) host polymer. The conductive filament was composed of a thermoplastic polymer (TPU) infused with carbon nanotubes (CNT)-grafted carbon fibres (CFs) produced via chemical vapour deposition. The mechanical, microstructural, and electrical properties of the grid elements and cementitious slabs reinforced with MGPC were comprehensively examined. The MGPC's performance in traffic flow monitoring, mechanical behaviour prediction, and damage localization was assessed through wheel tracking, asymmetric punch tests, piezoresistivity response evaluation, and digital image correlation techniques. Furthermore, the self-warming ability of the MGPC in cementitious composites was investigated using different voltages. The extruded TPU containing CNT-grafted CFs exhibited an electrical percolation threshold of approximately 5.0 wt%, resulting in a conductivity of around 70 S/m for the filaments. Incorporating MGPC as reinforcement within cementitious composite slabs led to notable enhancements, with flexural strength increasing by approximately 15 % and failure strain by up to 350 %. Wheel tracking tests revealed changes in the electrical: 5.8 % for 520 N and 7.8 % for 700 N wheel loads, with roughly 5.0 % average error in velocity detection. Transverse elements precisely detected wheel locations demonstrating the MGPC capabilities in accurately detecting wheel speed weight, and location. The study established strong correlations between electrical resistance changes, mechanical behaviour, and damage detection, affirming the MGPC's reliability and efficacy for damage monitoring and localization. The cementitious slab reinforced with MGPC reached around 52°C through a 20 V direct current, with a heating rate of 0.25°C/s and a power density of 142 W/m², showing its potential for practical applications such as self-healing and de-icing. However, design parameters such as mesh and conductive circuit configuration, long-term performance, as well as Life Cycle Assessment need further investigation.