Carbon Reinforcement Research Articles

Design and Analysis of Carbon Reinforced Composite Plate for Robotic Omni-Wheel: Replacement of Costly Metals

Design and Analysis of Carbon Reinforced Composite Plate for Robotic Omni-Wheel: Replacement of Costly Metals

Development and characterization of carbon fiber reinforcement in Aluminium metal matrix composites

Abstract Carbon fibers (CF) possess exceptional mechanical properties and the highest degree of chemical stability. However, carbon reinforcement in metal matrix composites is extremely scarce due to production difficulties, particularly in obtaining a uniform distribution. Carbon fiber reinforced composites are typically made using high temperature processing processes. However, the fibers must be coated with Ni or Cu in order to achieve effective particle dispersion; otherwise, there is a larger likelihood of intermetallic compound formation, which reduces the chances for enhanced properties. In this work, the metallurgical, mechanical, and tribological characteristics of the carbon fiber reinforcement in AA 7050 are examined. Uncoated carbon fibers are reinforced into the Aluminium matrix using a low temperature processing technique known as powder metallurgy. The AA 7050 matrix reinforced with carbon fibers at various weight percentages between 0 and 1.5. The samples undergone mechanical and metallurgical testing in accordance with ASTM guidelines. The findings indicate that the 0.25 weight percent carbon fiber reinforcement in the matrix increased the material’s hardness by 30% over the monolithic alloy, making it an excellent alternative for structural applications.

Interface modification strategy to construct SiC nanowires@pyrolytic carbon reinforcement for carbon fiber composites

AbstractDesigning and optimizing the interface of carbon fiber composites is the key to improve mechanical and biotribological properties. Carbon fiber‐reinforced hydroxyapatite‐epoxy matrix (CM) composites, which have excellent mechanical and biotribological properties, are often used to avoid artificial bone damage and improve the longevity of artificial bone. In this work, a SiC nanowires@pyrolytic carbon (SiCnws@PyC) is designed and incorporated into the CM to improve the mechanical and biotribological properties. SiCnws@PyC can promote bonding of the fiber/matrix interface and cohesion of the epoxy matrix. The mechanical and biotribological properties of CM are greatly improved because of the interface modification and reinforcement of SiCnws@PyC. The tensile strength and elastic modulus of SiCnws@PyC‐reinforced CM are 18.73% and 38.71% higher than those of CM, respectively. SiCnws@PyC‐reinforced CM has a 9.09% reduction in the friction coefficient and a 74.61% reduction in the wear rate. This study provides a promising methodology for the preparation of SiCnws@PyC‐reinforced CM with better stability and longevity for bone grafting applications.Highlights The mechanism of SiC nanowires@pyrolytic carbon (SiCnws@PyC) is explained. The SiCnws@PyC structure is designed into composites. PyC core‐shell transforms the structure of hydroxyapatite. The SiCnws@PyC enhances mechanical and biotribological properties of composites.

Surface engineering of carbon nanotube-carbon fiber networks for enhanced strength in additive manufacturing of nylon composites

This work quantifies the impact of chemical functionalization of carbon nanotubes and carbon fibres on the interfacial shear strength, tensile and interlaminar shear strength properties of additively manufactured nylon composites. The surface chemistry of functionalized carbon materials was evaluated through infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Single carbon fibre was dip-coated in a suspension of nanotubes and embedded into a nylon matrix. The fibres were pulled out to measure the interfacial shear strength, and the fibres with attached neat, carboxylated, and silanized nanotubes increased it by up to 67 %, 112 %, and 216 %, respectively. Composite samples were manufactured using a novel hybrid additive manufacturing method, which was able to deposit nylon layers and a suspension containing carbon reinforcement. The use of chemically functionalized nanotubes in the suspension led to carbon layers that improved tensile strength by 49 % and tensile modulus by 126 % over neat nylon. Functionalization of carbon reinforcement increased the interlaminar shear strength by up to 63 %. Overall, this paper demonstrates the importance of chemical modification in composite materials containing a large interface area of carbon materials.

Carbon Fiber-Based Vitrimer Composites: A Path toward Current Research That Is High-Performing, Useful, and Sustainable.

In the polymeric material industry, thermosets and related composites have played a substantial role in the production of rubber and plastics. One important subset of these is thermoset composites with carbon reinforcement. The incorporation of carbon fillers and fibers gives polymeric materials improved electrical and mechanical properties, among other benefits. However, the covalently crosslinked network of thermosets presents significant challenges for recycling and reprocessing because of its intractable nature. The introduction of vitrimer materials opens a new avenue to produce biodegradable and recyclable thermosets. Carbon-reinforced vitrimer composites are pursued for high-performance, long-lasting materials with attractive physical properties, the ability to be recycled and processed, and other features that respond uniquely to stimuli. The development of carbon-reinforced vitrimer composites over the last few years is summarized in this article. First, an overview of vitrimers and the methods used to prepare carbon fiber-reinforced vitrimer composites is provided. Because of the vitrimer nature of such composites, reprocessing, healing, and recycling are viable ways to greatly extend their service life; these approaches are thoroughly explained and summarized. The conclusion is our prediction for developing carbon-based vitrimer composites.

Capacity of Forests and Grasslands to Achieve Carbon Neutrality in China

Forests and grasslands play an important role in carbon cycling. They not only absorb CO2 from the air through vegetation biomass and soil carbon sinks, but also reduce and control the horizontal transport of soil carbon (i.e., reinforcing soil carbon storage via soil conservation), thus avoiding erosion-induced CO2 emissions. In this study, vegetation biomass and soil carbon sinks, soil carbon reinforcement and reduced carbon emissions via soil conservation by forests and grasslands were quantified on the scale of the whole of China. The analysis was based on the distribution of biomass and the soil carbon pool and soil erosion rates derived from national surveys, as well as carbon density values from field surveys and literature. In 2021, forests and grasslands in China generated 394.18 Mt C/year (y) of steady-state carbon sinks through vertical biomass and soil absorption. The biomass carbon sinks of grasslands, and those of leaves, twigs, flowers and fruits of the forests, were not taken into account when quantifying the stable biomass sink, because they can become net producers of CO2 due to seasonal withering and carryover, or they can form soil organic carbon as potential soil carbon sinks. The amount of horizontal soil carbon reinforcement in China’s forests and grasslands in 2021 was 20.31 Mt C/y, which was positively correlated with the reduction in the water erosion area; consequently, vertical emissions of approximately 14.89–29.78 Mt of CO2 into the atmosphere were avoided. Overall, in 2021, China’s forests and grasslands absorbed atmospheric CO2 and reduced emissions by 1.46–1.47 Gt CO2/y, equivalent to approximately 13% of China’s annual fossil CO2 emissions. This study demonstrates the fact that the adoption of forest and grassland measures sequesters carbon in soil and biota and reduces the risks of CO2 emissions by both vertical and horizontal paths, which is important for achieving carbon neutrality and mitigating climate change.

Fabrication of a novel high electrical conductivity Si3N4 matrix composite with Cu three-dimensional network structure by spark plasma sintering

Silicon nitride (Si3N4) ceramic matrix conductive composite materials have shown great promise as conductive layer materials for electrical transmission components. However, existing conductive phases struggle to form a three-dimensional (3D) interconnected network in Si3N4 matrix, resulting in poor electrical conductivity. This study proposed a spark plasma sintering (SPS) process utilizing Si3N4 as the substrate and Cu particles as the reinforcement phase to fabricate a novel electrical conductivity Si3N4/Cu composite material. The results indicated that the diffusion of Si atoms in Si3N4 facilitated the formation of copper silicide (CuiSi) interface between the two constituents during sintering, creating a strong chemical bonding for high conductivity. Simultaneously, composite materials with optimized Cu content formed a 3D interconnect network structure, providing a continuous path for electrical conduction. At Cu content of 30 vol%, the Si3N4/Cu composite exhibited a satisfying electrical conductivity of 295.37 S/m, which was 14 orders of magnitude higher than that of Si3N4. The composites also demonstrated a percolation phenomenon, with a theoretical percolation threshold of Cu particles at just 0.1 vol%, an order of magnitude lower than that of carbon reinforcement particles. Furthermore, an integrated design featuring external insulation and internal conductivity was achieved by wrapping a Si3N4 insulation layer around the conductive Si3N4/Cu composites. The fabricated insulation layer exhibited higher resistivity (1.12×1014 Ω) and a lower wear rate (1.3×10−6 mm3/N·m) compared to some contemporary insulation ceramics, while the conductive layer had a lower calorific value, making them excellent candidates for electrical transmission component materials.

Inhibition of Phase Transition in Amorphous Niobium Oxide by Covalent Carbon Reinforcement Enables Fast‐Charge and Long‐Duration Lithium Storage

AbstractNiobium oxides are potential anode materials for ultrafast and safe lithium‐ion batteries due to their high ionic conductivity and relatively high operation voltage. However, the electrochemically induced phase transformations that involve multi‐electron redox reactions in a wide voltage window cause rapid capacity degradation and poor rate capability. Here, a novel carbon‐covalent amorphous niobium oxide anode is reported to greatly suppress the phase transition during cycling via formation of strong Nb─O─C bonds, achieving high‐capacity, fast‐charge and long‐duration lithium storage. This amorphous structure and forming covalent carbon contribute to good volume accommodation and high electron conductivity. The carbon‐covalent amorphous Nb2O5 displays a high reversible capacity of 361.5 mAh g−1 at 0.1 A g−1 and excellent cycling stability with a capacity of 189.8 mAh g−1 at a high rate of 10 A g−1 after 9000 cycles. Structure characterizations reveal that the well‐preserved amorphous structure without phase transition during repeated Li+ insertion/desertion is responsible for the superior performance. This work opens a new avenue on rational design of high‐performance amorphous electrode materials for next‐generation batteries.

Enhancing Thermal, Viscoelastic, and Mechanical Properties of Silicone Rubber Matrix through Reinforcements for Use as a Medical Implant

The use of silicone rubber as an implant is limited due to its weak properties. In this study, the impact of various reinforcements, such as TiO<sub>2</sub> or SiO<sub>2</sub> nanoparticles, carbon, or polypropylene fiber micro reinforcements, on the mechanical, thermal, and viscoelastic properties of silicone rubber composites with RTV-4125 matrix was investigated. The composites were evaluated through several tests, including tensile, compression, FTIR, TGA, DMTA, and water adsorption tests. It was found that the composites' tensile strength and compressive stress were increased by adding reinforcements, with the most significant impact on tensile strength observed for SiO<sub>2</sub> and the most notable effect on compressive stress at a strain of 0.5 observed for polypropylene fiber. Moreover, the water absorption of the matrix was increased with the addition of reinforcements, with the highest increase observed for Titania nanoparticles. TGA analysis showed that all composites had higher thermal stability than the plain matrix, with the highest degradation temperature observed for the SR-C fiber composite and the highest degradation rate observed for SR-TiO<sub>2</sub>. Additionally, DMTA analysis revealed that TiO<sub>2</sub> nanoparticles considerably decreased the glass transition temperature of the matrix (%28.5), while the other reinforcements had a negligible effect on this temperature. The introduction of reinforcements had a positive impact on the mechanical, thermal, and viscoelastic properties of silicone rubber composites, and the findings of this study can contribute to the development of new and improved silicone rubber composites for implant applications.

THE CARBON-REINFORCED CONCRETE BUILDING – CUBE | BOX MANUFACTURING AND ASSEMBLING

The world's first building made entirely of non-metallic reinforcement was constructed in Dresden, Germany in 2022. It will be 220 m² in size and represents the entire process chain of carbon reinforced concrete construction. In Germany's largest construction research project C³-Carbon Concrete Composite, the topic of carbon reinforced concrete and its implementation have been researched and tested since 2014. All the research results were culminated in a lighthouse project, the C³ technology demonstration house CUBE. Based on these results, the boundary conditions for material, form and construction were derived and the necessary structural, experimental and design verifications were provided as well as the approvals for the construction of the building were granted. This paved the way for further new construction projects. Originally planned as an actual cube, architect of HENN Architects gave the CUBE a bit of a twist. And so, an interplay of two essential elements was created: the double-curved striking TWIST shells and the clearly structured BOX. In order to successfully realize the demonstration house CUBE, science and industry combined their competences in carbon reinforced concrete construction. Above all, the BOX precast complex demonstrates the extraordinary and immediate application potential of this composite material. The BOX, described in this paper, consists of semi-precast wall elements and precast slabs that can be manufactured with component thicknesses of just a few centimeters due to the use of carbon reinforcement. Manufacturing technology was tested in an automated precast plant and assembly was implemented at the construction site.

THE CARBON-REINFORCED CONCRETE BUILDING – CUBE | BOX MANUFACTURING AND ASSEMBLING

The world's first building made entirely of non-metallic reinforcement was constructed in Dresden, Germany in 2022. It will be 220 m² in size and represents the entire process chain of carbon reinforced concrete construction. In Germany's largest construction research project C³-Carbon Concrete Composite, the topic of carbon reinforced concrete and its implementation have been researched and tested since 2014. All the research results were culminated in a lighthouse project, the C³ technology demonstration house CUBE. Based on these results, the boundary conditions for material, form and construction were derived and the necessary structural, experimental and design verifications were provided as well as the approvals for the construction of the building were granted. This paved the way for further new construction projects. Originally planned as an actual cube, architect of HENN Architects gave the CUBE a bit of a twist. And so, an interplay of two essential elements was created: the double-curved striking TWIST shells and the clearly structured BOX. In order to successfully realize the demonstration house CUBE, science and industry combined their competences in carbon reinforced concrete construction. Above all, the BOX precast complex demonstrates the extraordinary and immediate application potential of this composite material. The BOX, described in this paper, consists of semi-precast wall elements and precast slabs that can be manufactured with component thicknesses of just a few centimeters due to the use of carbon reinforcement. Manufacturing technology was tested in an automated precast plant and assembly was implemented at the construction site.

Hygrothermal progressive damage in open-hole compression of composite laminates with aligned carbon nanotube interlaminar reinforcement studied by X-ray micro-computed tomography

Hierarchical nanoengineered composite laminates were created with through-thickness-aligned carbon nanotube (A-CNT) reinforcement of unidirectional carbon (micro) fiber/epoxy laminae in their failure-prone interlaminar regions, forming a multiscale “nanostitched” architecture. Motivated by previous mechanical enhancements for similar nanostitched laminates in ambient environments, hygrothermal effects on the 3D strengthening and toughening mechanisms of nanostitched laminates are investigated here for the first time, focusing on standard open-hole compression (OHC) testing of quasi-isotropic laminates. We report that the hygrothermal conditions of −55 °C/DRY and 100 °C/DRY correspond to ultimate strength increases of 2.6% and 5.9%, respectively, for nanostitched laminates over the baseline; and, room temperature/50% relative humidity (RT/50% RH) and 100 °C/wet conditions exhibit no change in ultimate strength, suggesting correlation of positive nanostitch effects with increased polymer brittleness. Subsequently, damage progression in step-wise interrupted OHC loading for selected hygrothermal conditions (RT/50% RH and 100 °C/DRY) was performed in coordination with high-resolution ex situ X-ray micro-computed tomography for various load steps up to 98% of failure load. No clear differences due to nanostitch in the damage progression are found up to 98% of ultimate strength, suggesting that the reinforcement effect is associated with interlaminar strength at ultimate load, and not pre-ultimate damage. This study contributes first insights from high-resolution experimental mapping of nanostitched composite progressive damage subjected to hygrothermal conditions that may guide and inform mechanical enhancement approaches and improved progressive damage models. Future work is suggested to expand the environmental conditions considered, as well as visualize progressive damage nearer to failure to identify nanostitch effects on complex multimodal failure.

Effect of carbon nanotubes content on compressive properties and deformation behaviors of aluminum matrix composite foams

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams.

Diagnosis and Monitoring of Tunnel Lining Defects by Using Comprehensive Geophysical Prospecting and Fiber Bragg Grating Strain Sensor.

Tunnel excavation induces the stress redistribution of surrounding rock. In this excavation process, the elastic strain in the rock is quickly released. When the maximum stress on the tunnel lining exceeds the concrete's load-bearing capacity, it causes cracking of the lining. Comprehensive geophysical exploration methods, including seismic computerized tomography, the high-density electrical method, and the ultrasonic single-plane test, indicated the presence of incomplete distribution of broken rock along the tunnel axis. Based on the geophysical exploration results, a carbon-fiber-strengthened tunnel simulation model was established to analyze the mechanical characteristics of the structure and provide a theoretical basis for sensor deployment. Fiber Bragg grating (FBG) strain sensors were used to measure the stress and strain changes in the second lining concrete after carbon reinforcement. Meanwhile, one temperature sensor was installed in each section to enable temperature compensation. The monitoring results demonstrated that the stress-strain of the second lining fluctuated within a small range, and the lining did not show any crack expansion behavior, which indicated that carbon-fiber-reinforced polymer (CFRP) played an effective role in controlling the structural deformation. Therefore, the combined detection of physical exploration and FBG sensors for the structure provided an effective monitoring method for evaluating tunnel stability.

Alkali-Activated Copper Slag with Carbon Reinforcement: Effects of Metakaolinite, OPC and Surfactants

Copper slag is an industrial residue with a large unutilized fraction. This study presents the development of alkali-activated composites from a copper slag named Koranel®. The effects of metakaolinite, ordinary Portland cement (OPC) and surfactants were investigated. The reactivity of Koranel with potassium silicate solutions with molar ratio R = SiO2/K2O varying from 1 to 2.75, with 0.25 intervals, was investigated using isothermal calorimetry. The reactivity was relatively low at 20 °C; the reaction started after a few hours with a low silica modulus, to several weeks with the highest silica modulus. The substitution of Koranel by OPC (5 wt.%) or by metakaolinite (10–20 wt.%), both led to higher reaction heat and rate; meanwhile, the addition of 2 wt.% polyethylene glycol/2-methyl 2,4 pentanediol delayed the reaction time in the system containing metakaolinite. Raising the curing temperature from 20 °C to 80 °C shortened the setting time of the low reactive systems, from several days to almost instantaneous, opening perspectives for their application in the production of prepreg composite materials. The use of carbon fabric as reinforcement in the alkali-activated matrix led to composite materials with flexural strength reaching 88 MPa and elastic modulus of about 19 GPa—interesting for engineering applications such as high-strength lightweight panels.

Microstructure and properties of aluminium matrix hybrid nanocomposite

ABSTRACT Aluminium metal matrix nanocomposites (MMNCs) reinforced with particulate have been in the limelight recently due to their improved tribological and mechanical properties such as stiffness, strength, impact resistance, wear resistance, etc. It is well known that carbon nanotube and silicon carbide nanomaterials are widely used as reinforcements in various types of metal or alloy matrix materials. However, hybrid metal matrix nanocomposites reinforced with more than one type nanomaterials are rarely reported in the literature. In this work, a novel aluminium matrix hybrid nanocomposite with carbon nanotube and nano SiC has been fabricated. Properties of hybrid nanocomposites are compared with nanocomposites reinforced with individual reinforcements. Vicker’s micro-hardness property of specimens was tested at 100 gmf load applied at 10 s dwell time. The hardness and compressive strength have increased 111% and 58%, respectively with the reinforcement of nanoparticles in the metal matrix. Dry wear property of specimens was carried out at 35, 40 and 45 N load with variable speeds viz. 500, 550 and 600 rpm. Wear resistance increases as the carbon reinforcement increases in the metal matrix. The wear mechanism of nanocomposite materials has been evaluated by using scanning electron microscopic analysis.

High-Temperature Behavior of Carbon Reinforced Concrete

Carbon reinforced concrete is perceived by industry as a promising alternative to the currently established construction products. Previous building authority approvals and approvals for this construction method largely exclude questions of preventive fire protection with regard to load-bearing behavior under fire because there are hardly any reliable research results available in this field. This article shows the results of experimental investigations including thermogravimetric analyses of carbon reinforcement and tensile tests on the composite material carbon reinforced concrete. The thermogravimetric analyses show the loss of mass of the carbon reinforcement under a temperature load. A decomposition of the coating system of the carbon fibers and, with increasing temperature load, also of the carbon was observed. By varying various boundary conditions, such as the heating rate and the oxygen content present, their influences can be assessed. Stationary and non-stationary tensile tests on strip-shaped carbon reinforced concrete specimens were used to determine the load-bearing and deformation behavior in the high-temperature range up to 700 °C. The investigations were carried out under constant heating rates of 2 K/min and 10 K/min. This made it possible to obtain stress-strain curves and information on the various temperature-dependent deformation components from mechanical strains and load-independent strains. The time- and temperature-dependent decomposition of the carbon resulted in a reduction in the tensile load-bearing capacity of the reinforcement in the high-temperature range. This effect can be taken into account by considering the cross-sectional loss of the carbon reinforcement in a hot design.

New perspectives on carbon reinforced concrete structures—Why new composites need new design strategies

AbstractIn civil engineering, carbon is typically regarded as a modern material to serve as reinforcement in concrete structures. Compared to steel reinforcement, it features two substantial benefits: It is not sensitive to corrosion, and has an enormously increased tensile strength. In contrast, carbon reinforcement is sensitive to lateral pressure and lacks the property of strain hardening. As a first step of establishing carbon reinforced concrete as a new building composite material, carbon reinforcement has basically served to replace the state‐of‐the‐art steel reinforcement. This target led to pioneering findings with respect to determining the material properties of the composite and developing advanced individual components. However, barely substituting steel by carbon does not allow to fully utilize the carbon's benefits while its disadvantageous properties reveal the limits of this approach. Instead, novel design principles are required to meet the material's nature aiming at appropriately using its beneficial properties. Currently, new construction principles are being researched for high‐performance building material combinations such as textile and carbon reinforced concrete. This paper provides an overview of baselines in the preliminary stages of this research. The overview includes history, inspiration, concrete matrices, non‐metallic reinforcement, structural elements, modeling, production, tomography, and sustainability. The objective of the study is to provide a baseline for the envisaged development of principles for future construction: radically new concepts for the design, modeling, construction, manufacturing, and use of sustainable, resource‐efficient building elements made of mineral building materials with the aim of entirely benefiting from the materials' potential.

Enhanced mechanical properties of multi-scaled carbon reinforcements in ternary epoxy composites materials

Carbon nanotubes (CNT) and graphene have widely used as reinforcements in epoxy for various aims and applications since their ‘discovery’. For example, in the area of aviation and aerospace materials, carbon reinforcements are desirable as they offer solutions for light weight yet mechanically enhanced materials. The objective of this work is to investigate the effects of adding combination of carbon fillers of different aspect ratios on the thermal mechanical, Young’s Modulus and Fracture Toughness properties of the resultant epoxy composites. The carbon fillers include carbon nanotubes (CNT), graphene, and carbon black (CB) and their combined loading will be varied from 0.5 wt. % until 7 wt. % to form sets of binary epoxy composites and a ternary epoxy composites. All of the fillers are kept at the 1:1 weight ratio for CB + CNT, CB + Graphene, CNT + Graphene, and CB + CNT + Graphene. Among these combinations, the system with ternary fillers at 7 wt.% demonstrated the highest value of glass transition temperature (Tg) and KIC, and Young’s Modulus. The percent improvement for glass transition temperature (Tg) and KIC, and Young’s Modulus compared to neat epoxy are 9.5 %, 571%, and 58.3%, respectively. This work clearly demonstrated the effectiveness of employing various carbon fillers with different aspect ratio and morphology in enhancing the values of mechanical properties of epoxy system.

WITHDRAWN: Utilization of waste coffee ground ash as fine aggregates in concrete: Enhancing shear strength through activated carbon reinforcement

This study addresses burgeoning environmental concerns amid rising global coffee consumption amid rising global coffee consumption by exploring the viability of utilizing waste coffee ground ash (SCG) as a sustainable fine aggregate in concrete production. Significant improvements are noted by investigating the impact of SCG on the shear strength of standard concrete and enhancing properties through activated carbon reinforcement derived from SCG via physical activation. Experimental results reveal that incorporating up to 1.5% activated carbon by weight markedly boosts early shear strength. Moreover, composites with a small inclusion of activated carbon demonstrate superior shear power during curing compared to conventional mixes. The study employs Teaching-Learning Optimization (TLBO) and Extreme Learning Machine (ELM) techniques to forecast shear strength accurately. ELM emerges superior, showcasing heightened accuracy, lower RMSE, and superior r and R2 values compared to TLBO. Conclusively, leveraging waste coffee ground ash as a fine aggregate in concrete not only presents an effective method for enhancing shear strength but also underscores a promising pathway toward sustainable waste management and reduced environmental impact, reflecting a pivotal stride in harmonizing concrete performance enhancement with eco-friendly practices.