Flexural Strength Characteristics Research Articles

Flexural Behaviour and Environmental Impact of African Fan Palm Reinforced Concrete Beams under Symmetrical Loading Conditions

The paper presents the results of investigation on reinforced beams adopting eco-friendly materials for sustainable concrete. The use of African fan palm is explored to mitigate the environmental impact aimed at reducing carbon emissions associated with the production and use of steel reinforcement. The beams were tested under a four -point loading system with the ends simply supported. The test comprised twenty-three beams that were reinforced with African fan palm bars whilst two beams were reinforced with mild steel bars to serve as control beams. The study investigated the flexural strength and deformation characteristics of the beams under monotonic loading. Two concrete strengths of 15.34N/mm2 or 22.37N/mm2 were adopted and proposed optimal tensile ratios for an under reinforced fan palm section. The parameters considered included the tension bars ratio (ρ), concrete compressive strength, span-to-effective-depth ratio and loading conditions. A linear elastic behaviour of both fan palm and steel reinforced concrete beams was observed to the point of first crack load beyond which the beam stiffness continued to reduce until failure. A comparison of the experimental results with results of theoretical analysis of the beams revealed that a 1.22% increase in the tensile ratio of steel in the control beams increased the cracking moment (Mcr) to 36%, while the fan palm beam of the same size and same concrete strength with a higher tensile ratio of 9.69% exhibited a lower Mcr of 11.86%. This shows a significant effect of reinforcing steel bars on concrete cracking compared to the fan palm. The averages of experimental to theoretical failure loads of fan palm to steel were compared with failure loads of 36.52kN to 20.19kN and 32kN to 19.78kN respectively. These results of the study based on the failure mode, and failure loads, highlights the suitability of using African fan palm as substitute reinforcing material for low rise buildings. Furthermore, the study also proposed minimum and maximum tensile ratio of 0.76% and 5.60% respectively for fan palm reinforced concrete beams based on the Indian Standard and modulus of elasticity of steel.

Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach

Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a0/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (GF) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,KICini of 0.928 MPa√m, KICuns of 6.99 MPa√m and KICini/ KICuns of 0.133. A maximum GF of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, KICini of 0.612 MPa√m,KICuns of 1.16 MPa√m, KICini/ KICuns of 0.528 and GF of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a0/d 0.5 and for both Initial Fracture Toughness (KICini) and Unstable Fracture Toughness (KICuns) at FA 0 %, SF 0.75 % and a0/d 0.4. For both the ratio of initial to unstable fracture toughness (KICini/ KICuns) and fracture energy (GF), the optimum combination was FA 0 %, SF 0.75 % and a0/d 0.2. Furthermore, the results indicate that FA significantly influences KICini, while SF predominantly affects all other parameters. The predictive performance of the regression equations demonstrates good agreement with experimental outcomes.

Investigation of the Thermal and Mechanical Properties of Glass Fiber Reinforced ABS/Epoxy Blended Polymer Composite

This research investigates the formation of polymer blends by blending Epoxy LY556 with Acrylonitrile-Butadiene-Styrene (ABS) at weight percentages ranging from 2 to 10% wt. The thermal properties, morphological characteristics, tensile strength, flexural strength, and interlaminar shear strength (ILSS) characteristics of these composites were examined. The X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectrometer (FTIR) studies confirmed the presence of binary blends. The miscibility of epoxy/ABS blends is shown by the presence of a single melting peak in the Differential Scanning Calorimetry (DSC) analysis. The Thermogravimetric Analysis (TGA) findings indicate that epoxy and ABS blends exhibit greater thermal stability than pure epoxy. The tensile strength increased from 183.6 to 380.6 MPa, flexural strength increased from 165.3 MPa to 335.6 MPa, ILSS increased from 32.4 MPa to 72 MPa for 8% wt. of ABS blending, and the laminates witnessed a decrease in density and hardness values. The Scanning Electron Microscopy (SEM) images demonstrate the commendable blending characteristics and the synergistic impact of the ABS/Epoxy composite, yielding superior outcomes to the pure epoxy material.

Fabrication of ramie/hemp fibers-reinforced hybrid polymer composite—A comprehensive study on biological and structural application

This study primarily investigates the antibacterial properties, tensile strength, flexural strength, impact strength, hardness, and microstructural characteristics of a composite, utilizing Scanning Electron Microscopy (SEM) for detailed analysis. The composite, crafted through a hand layup technique, optimally blends ramie and hemp fibers within an epoxy matrix. Its antibacterial efficacy was rigorously tested against common bacterial strains, demonstrating significant potential for medical and hygienic applications. The evaluation of tensile strength revealed the composite’s enhanced capability to withstand longitudinal stresses, with a peak strength of 37.81 MPa, achieved by increasing ramie fiber content. In addition, a flexural strength of 39.72 MPa underscored the material’s robust resistance to bending forces, crucial for structural uses. The composite’s impact strength, accessed via the Izod impact test, registered at 0.021 J/m2, indicating its ability to absorb and dissipate energy upon sudden impacts, making it ideal for automotive and protective gear applications. The Rockwell hardness test further quantified the composite’s resistance to surface indentation, vital for wear-resistant surfaces. SEM analysis offered a comprehensive view of the microstructural dynamics between the fibers and the matrix, especially under tensile stress, highlighting the intricacies of fiber–matrix adhesion, crack propagation, and overall composite integrity. Notably, the antibacterial properties were confirmed by an 18 mm inhibition zone, which showcases the composite’s ability to inhibit bacterial growth effectively.

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.

Influence of Bacteria in Self – Healing Fly Ash Concrete

Traditional concrete is considered brittle, rigid and susceptible to cracks. Synthetic polymers used for the repair of cracks are susceptible to ultraviolet radiations, high cost and emanate toxic gases. This project presents the results of an experimental investigation carried out to evaluate the influence of Bacillus Megaterium bacteria on the compressive strength, split tensile strength, flexural strength and self-healing characteristics of concrete made without and with fly ash. Cement was replaced with four percentages (10, 20, 30 and 40) with fly ash by weight. A cell concentration of 105 cells/ml of bacteria was used in making the concrete mixes. Tests were performed at the age of 28 days. Test results indicated that the inclusion of Bacillus Megaterium in fly ash concrete enhanced the compressive, split tensile and flexural strength. This improvement in strength was due to deposition on the bacteria cell surfaces within the pores. The present work highlights the influence of bacteria on the properties of concrete made with supplementary cementing material such as like fly ash. Usage of bacteria like Bacillus Megaterium improves strength and durability of fly ash concrete through self-healing effect

Experimental Investigation of Sustainable Concrete Production using Blast Furnace as A Cement Substitute- A art of Review

The pursuit of sustainable construction practices has led to a growing interest in alternative materials that can reduce the environmental impact of traditional concrete production. This experimental study focuses on the utilization of blast furnace slag as a substitute for cement in concrete, aiming to assess its mechanical properties, environmental impact, and overall sustainability. The primary objectives of this research are threefold. Firstly, the study seeks to evaluate the mechanical properties of concrete by varying the content of blast furnace slag in the mix, with a specific emphasis on strength, durability, and structural performance. This involves conducting a comprehensive analysis of the concrete's compressive strength, flexural strength, and other relevant mechanical characteristics. Secondly, a life cycle assessment (LCA) will be employed to analyze the environmental impact of the concrete mixtures. This assessment will compare carbon dioxide (CO2) emissions, energy consumption, and overall sustainability of the concrete produced with varying percentages of blast furnace slag. The LCA will provide valuable insights into the environmental implications of using slag as a cement substitute, aiding in the identification of eco-friendlier concrete production practices. Lastly, the research aims to assess the environmental impact of blast furnace slag itself when employed as a cement substitute. This involves examining the production, transportation, and incorporation of blast furnace slag into the concrete mix, providing a holistic view of its sustainability across the entire life cycle. The experimental approach involves the meticulous design of concrete mixes with different percentages of cement replaced by blast furnace slag. The varying mix designs will be tested for mechanical properties, and the data obtained will be used to draw correlations between slag content and concrete performance. In summary, this research endeavors to contribute to the body of knowledge surrounding sustainable concrete production by exploring the mechanical, environmental, and sustainability aspects of utilizing blast furnace slag as a cement substitute. The findings of this study are anticipated to provide valuable insights for the construction industry to adopt more environmentally friendly practices while maintaining or enhancing concrete performance.

Strength Optimization of Nanocomposite Cementitious Materials Using Nanoscale Modifications

Represent Volume Element (RVE) is broadly used by investigators to control the properties of nano-cementitious materials. This paper focuses on analyzing a set of RVE data and proposes parametric equations for determining the compressive and flexural strength characteristics (σc and σf). Primarily, a parametric study is performed with RVE analysis. The essential design parameters are used to fit rational equations. The RVE data are also applied to train artificial neural networks of σc and σf. RVE, neural networks, and rational equations are correlated. Regression equations are validated with the experimental study. SEM, TEM, XRD, and FTIR results are carried out in the microscopic and mechanical analysis for carbon nanofiber cement composites, which can lift their strength, constancy, integrity, and density and reinforce the composite microstructure. Lastly, the Pareto-optimal design results are presented with a multi-objective optimization problem.

Rheological and Flexural Strength Characteristics of Cement Mixtures through the Synergistic Effects of Graphene Oxide and PVA Fibers.

This study investigates the synergistic effects of incorporating graphene oxide (GO) and polyvinyl alcohol (PVA) fibers into cement paste mixtures, aiming to modify their rheological properties and flexural behaviors with resistance to crack formation. The relationship between static yield stress and critical shear strain was examined in ten cement paste mixtures with varying concentrations of 6 mm and 12 mm PVA fibers and 0.05% GO. Additionally, viscosity analyses were performed. For the specimens fabricated from these mixtures, flexural strength tests were conducted using the Digital Image Correlation (DIC) technique for precise strain analysis under load history. The results indicated a significant increase in static yield stress, viscosity, and critical shear strain due to the combined addition of GO and PVA fibers, more so than when added individually. Notably, in PVA fiber-reinforced cement mixtures, the integration of GO increased the crack initiation load by up to 23% and enhanced pre-crack strain by 30 to 50%, demonstrating a notable delay in crack initiation and a reduction in crack propagation. Microstructural analyses using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) revealed a concentrated presence of GO around and on the PVA fibers. This promotes increased C-S-H gel formation, resulting in a denser microstructure. Additionally, GO effectively interacts with PVA fibers, enhancing the adherence of hydration products at their interface.

EXPLORING THE MECHANICAL PROPERTIES OF LEAF SPRINGS REINFORCED WITH FIBRE COMPOSITES

To determine whether eggshell particles can be used as a filler material to improve mechanical properties, this study examines the mechanical characteristics of a hybrid material made of eggshell particles and glass-fiber-reinforced polymer (GFRP). To obtain the appropriate particle size, the eggshells are cleaned, crushed, and sieved as part of the experimental approach. The eggshell fragments are then mixed with resin and glass fibres using a vacuum-assisted resin-transfer moulding process to create GFRP composites. The produced GFRP composites’ flexural strength, stiffness, fatigue stability, and other pertinent characteristics are evaluated with practical tests. Notably, certain qualities are enhanced with the inclusion of eggshell particles containing 110 % of the weight of fibroin. In comparison to conventional GFRP composites, which only consider fatigue life during the exhaustion testing phase, the results reveal a 15% increase in the enhancement rate. The findings imply that adding eggshell particles to GFRP composites has tremendous opportunities for progress, notably in automotive applications, and more specifically in the use of leaf springs. The hybrid material’s better mechanical characteristics suggest that it may be possible to improve the performance and longevity of leaf-spring applications. This study advances the investigation of low-cost, environmentally friendly materials for improving composite materials’ mechanical properties in the automobile sector. The application of eco-friendly and effective solutions in the production of automobiles may result from more study and development in this field.

Mechanical Properties of Zirconia Materials with Different Translucency: An In Vitro Study.

To investigate the biaxial flexural strength of zirconia materials with different translucency before and after aging procedures and to evaluate the effects of aging on hardness and surface characteristics. A total of 90 disc-shaped specimens (n = 30 each) were prepared from translucent (Upcera-ST, Upcera Dental), high translucent (Katana HT, Kuraray Noritake), and ultra high translucent (Katana UTML, Kuraray Noritake) zirconia materials to a ø.16 ±1.2 mm thickness. The different translucency discs were then divided into three subgroups; one group was subjected to aging in a chewing simulator (n = 10), one group was aged with thermocycling (n = 10), and one was a control group (n = 10). Biaxial flexural strength, Vickers hardness, and surface characteristics were examined for all discs. The data were analyzed using the Shapiro-Wilk (P = .05), Mann-Whitney U, and Kruskal-Wallis H tests. Fracture strength was determined using biaxial bending strength tests, and Weibull analysis was used to analyze the resulting data. A statistically significant difference was found among zirconia materials with different translucency in terms of fracture strength. On average, fracture strength was highest in the Upcera ST group (1,932.87 MPa) and lowest in the Katana UTML group (1,073.6 MPa; P = .001). The results of Weibull analysis showed a statistically similar distribution for all groups. Aging procedures did not cause significant differences in fracture strength and hardness. The fracture strength of the zirconia materials with different translucency was considered acceptable for intraoral use.

Feasibility of Recycled HDPE Planks for Sustainable Furniture Applications: A Physio-Mechanical Study

Plastic waste generation has become a pressing environmental challenge due to the widespread use of plastic materials, which offer versatility, durability, and cost-effectiveness. This study investigates the feasibility of fabricating recycled high-density polyethene (HDPE) planks for furniture applications by evaluating their physio-mechanical properties. The research addresses the urgent need for effective waste management strategies, mainly plastic waste recycling, to mitigate environmental sustainability concerns. The study analyses the recycled HDPE planks’ tensile strength, flexural strength, and water absorption characteristics. The results indicate that the planks exhibit an average tensile strength of 14.36 ± 1.24 MPa and flexural strength of 46.57 ± 3.11 MPa, highlighting their suitability for furniture applications. Moreover, less than 0.01% water absorption rate confirms their capability to withstand outdoor conditions. A survey was conducted with 70 participants to gather feedback on the furniture product and gauge user perception. Most users expressed high satisfaction and appreciation for this sustainable initiative, recognizing the importance of promoting daily sustainability practices. This positive user feedback reinforces the significance of waste management practices and encourages the broader adoption of sustainable engineering solutions. This study offers compelling evidence supporting the utilization of recycled HDPE planks in furniture applications. It underscores the importance of effective waste management in addressing environmental concerns associated with plastic waste. The study’s findings highlight the feasibility of implementing sustainable engineering solutions to catalyze broader recycling practices adoption and promote a sustainable lifestyle.

Effect of Denim Waste Fibres on Technical Properties of Cementitious Lightweight Composite Mortars

The aim of this study was to investigate the utilization of recycled denim waste fibers (DWF) for reinforcing cementitious lightweight composite mortar (CLCM). The research focused on evaluating how the addition of DWF affected various aspects of CLCMs, such as flowability, fresh and hardened unit weight, porosity, water absorption, flexural strength, compressive strength, and load-deformation characteristics. Different proportions of fibers (0, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 wt.% of cement) were incorporated into the CLCM. The results showed a slight decrease in both fresh and hardened unit weights compared to the reference. It was noted that the consistency of the mortars declined with the increasing addition of fibers. Additionally, the inclusion of any amount of fiber led to an enhancement in the mechanical properties of the lightweight mortars. Furthermore, the reference mortar exhibited less deformation under load, indicating its higher brittleness. Moreover, the study observed that the incorporation of DWFs had the ability to simultaneously improve both the ultimate load-bearing capacity and deformation of the mortars.

Investigating the Effect of Polypropylene Fiber on Mechanical Features of a Geopolymer-Stabilized Silty Soil

This study investigates the stabilization of silty soil using alkali-activated fly ash and fibers with lengths of 3 mm and 12 mm. The study examines the effects of hybrid fiber length, fiber content, fly ash content, and activator content on the mechanical properties of the geopolymerstabilized samples. The objectives of this paper are 1) to examine the effect of activator content and fly ash content on the UCS, Al/Si ratio, and SiO2/Na2O ratio of the stabilized samples using a statistical approach, 2) to investigate the effect of hybrid fiber length on UCS, secant modulus, flexural strength, toughness, and flexural load-deformation characteristics of the stabilized soil. A statistical approach was employed to investigate the relationship between fly ash content, alkali activator content, and UCS value. Optimal fly ash content and alkali activator content were determined based on the statistical model. The geopolymer structure of the stabilized soil was characterized via SEM, EDS, XRD, and FTIR analyses. The effects of fly ash and alkali activator content on UCS, Al/Si ratio, and SiO2/Na2O ratio were determined using the derived statistical model. The study demonstrated that activator content, a critical factor in compaction, significantly influences the UCS value, as much as the effect of the Si/Al and SiO2/Na2O ratios. Additionally, variations in fly ash content led to an increase in the UCS value of up to 15%. Moreover, changing the activator content resulted in a maximum 12-fold increase in UCS value. Incorporating hybrid fibers for stabilization led to higher secant modulus (up to 30%), flexural strength (up to 6%), and ductility without compromising UCS.

Enhancing Reinforced Concrete Beams: Investigating Steel Dust as a Cement Substitute

This research undertook an extensive examination of the ramifications of integrating steel dust as a partial substitute for cement within reinforced concrete beams. The investigation encompassed an assessment of various facets, encompassing the workability of the concrete mixture, alongside crucial mechanical properties such as compressive strength, split tensile strength, flexural strength, ultrasonic pulse velocity (UPV), and elasticity modulus. The findings unveiled a notable reduction in workability as the proportion of steel dust increased within the mixture, with a consequential substantial impact on the elasticity modulus. Notably, compressive strength exhibited an enhancement at a 10% replacement of cement yet exhibited a decline with higher degrees of cement substitution. The inclusion of steel dust led to the formulation of adjusted equations pertaining to split tensile and flexural strength characteristics within the mixture. Remarkably, the incorporation of 10% steel dust yielded an increase in ductility. Conversely, at a 30% steel dust inclusion level, ductility diminished alongside a reduction in the maximum load-bearing capacity. In light of these findings, it is imperative to exercise prudence when considering the utilization of steel dust as a cement substitute, particularly when approaching or exceeding the 10% replacement level threshold. Further comprehensive research is imperative to acquire a comprehensive understanding of its implications and its susceptibility to potential corrosion concerns.

Influence Utilization Waste Plastic Polyethylene Terephthalate on the Flexural Strength of Concrete with Use East Kalimantan Aggregate

Environmental pollution is still an issue that cannot be ignored. This type of waste causes environmental pollution due to its large and difficult to be recycled is Polyethylene Terephthalate (PET) plastic. So it is important to make an effort to utilize the plastic. On the other hand in the world of construction, the use of concrete increases every day causing the need for many new material sources in order to cover the needs of concrete mixtures. One of the abundant sources of aggregate is East Kalimantan aggregate but has not been used much. so combining East Kalimantan aggregate and PET plastic as a concrete constituent material becomes interesting to be analyzed, especially to determine the characteristics of the flexural strength of concrete. The flexural strength is based on SNI 03-4431-2011 method and tested at the age of 14 and 28 days. PET plastic chopped to a size of 5 cm long and 1-3 mm wide with variations 0.5%; 0.65%; and 0.8% of the weight of sand. The total number of samples is 24 blocks size of 15 × 15 × 60 cm. The results indicate that the flexural strength characteristics of concrete using local East Kalimantan aggregates and using PET plastic as a partial substitute for fine aggregate increased as the number of PET substitutions. Concrete without PET plastic has 3.187 MPa. In comparison with to normal concrete, 0.5% PET substitution increased by 3.07%, 0.65% PET variation increased by 3.63% and 0.8% PET variation increased by 4.32%.

FLEXURAL STRENGTH CHARACTERISTICS OF PAWPAW LEAF ASH AND BAMBOO LEAF ASH BLENDED CEMENT CONCRETE

This research focuses on flexural strength characteristics of pawpaw leaf ash and bamboo leaf ash blended cement concrete. Several tests were carried out, according to BS and ASTM requirements to determine the physical and mechanical properties of pawpaw leaf ash and bamboo leaf ash blended cement concrete, investigate the effects of curing age on flexural strength characteristics of pawpaw leaf ash and bamboo leaf ash blended cement concrete and examine the effects of percentage replacement of cement with pawpaw leaf ash and bamboo leaf ash blended cement concrete on flexural strength characteristics. A total of 60 cubes were cast, cured in water for 7, 14, 21 and 28days. Test results showed that the flexural strength of the concrete cubes increases with an increase in the curing age and decreases with increasing percentage replacement of cement with pawpaw leaf ash and bamboo leaf ash. The optimum replacement level of pawpaw leaf ash and bamboo leaf ash was obtained to be 5%. The study concluded that concrete containing the cement blends of cement and Pawpaw leaf ash and bamboo leaf ash at a replacement level of 5% is only recommendable for use in light concrete works construction.

Formulation and Performance of Model Concrete in Reduced-Scale Physical Model Tests.

The utility of geotechnical centrifuge tests depends on how correctly they predict the physical and mechanical behaviour of concrete. In this study, a model concrete material that consisted of α-gypsum plaster, fine silica sand, and water was developed. An orthogonal test design was used to evaluate the effect of the mix proportion on the model concrete performance. The physical (i.e., flowability and bleeding rate) and mechanical (i.e., compressive and flexural strength) characteristics were considered as indices. Various mix ratios resulted in remarkable relative contributions to model concrete performance, and each raw material dosage exhibited positive or negative synergy. The water-plaster ratio (W/P) and aggregate-plaster ratio (A/P) strongly influenced the mechanical and physical characteristics, respectively. Multiple linear regression analysis (MLRA) was carried out to determine a forecast model for various small-scale test demands. Finally, the applicability and outlines of the presented forecasting method in proportioning design were evaluated by typical use of model concrete in small-scale model tests.

Evaluation of Polycaprolactone Applicability for Manufacturing High-Performance Cellulose Nanocrystal Cement Composites.

This experimental study examined the aplication effect of polycaprolactone (PCL), an organic resin material with excellent elasticity and ductility, on improving the mechanical performance of cellulose nanocrystal (CNC) cement composites. PCL was compared according to its shape, and in the case of Granules, which is the basic shape, interfacial adhesion with cement was not achieved, so a dichloromethane (DCM) solution was used to dissolve and use the Granules form. As a method for bonding PCL to the CNC surface, the CNC surface was modified using 3-aminopropyltriethoxysilane (APTES), and surface silylation was confirmed through Fourier transform infrared spectroscopy (FT-IR) analysis. In order to evaluate the dispersibility according to the application of PCL to the modified CNC, particle size analysis (PSA) and zeta potential analysis were performed according to the PCL mixing ratio. Through the PSA and zeta potential values, the highest dispersion stability was shown at 1 vol.%, the cohesive force of CNC was low, and the dispersion stability was high according to the application of PCL. According to the results of the dispersion stability evaluation, the degree of hydration of the dissolved PCL 1 vol.%, CNC-only specimens, and plain specimens were analyzed. CNC acted as a water channel inside the cement to accelerate hydration in the non-hydrated area, resulting in an increased degree of hydration. However, the incorporation of PCL showed a low degree of hydration, and the analysis of strength characteristics also showed a decrease of approximately 27% compared with that of plain specimens. This was because the bonding with SiO2 was not smooth owing to the solvent, thus affecting internal hydration. In order to investigate the effect of the PCL shape, the compressive and flexural strength characteristics were compared using PCL powder as an additional parameter. The compressive strength and flexural strength were improved by about 54% and 26%, respectively, in the PCL powder 15 wt% specimen compared to the general specimen. Scanning electron microscopy (SEM) analysis confirmed that the filler effect, which made the microporous structure denser, affects the mechanical performance improvement.

Influence of Fiber Content on the Flexural Strength and Physical Properties of Abaca Fiber-Cement-Gypsum Board

Cement-gypsum board has been used widely in construction project as a non-structural material. Commercial cement-gypsum board is mostly reinforced with synthetic fiber such as glass fiber. Environment consideration leads to the replacement of synthetic component with natural one in industrial product. In this study, a cement-gypsum board with natural fiber reinforcement—specifically, abaca fiber—was created. To examine the impact of fiber content on the flexural strength and other physical characteristics of cement-gypsum panels, cement-gypsum panels with varying amounts of abaca fiber content (0%, 1%, 2%, 3%, and 4%) were created. The experiment and its materials were created in accordance with Indonesian Standard SNI 01-4449-2006. The experiment's findings demonstrated that the amount of fiber in abaca-cement-gypsum panels had a substantial impact on their flexural strength, density, moisture content, water absorption, and thickness development. The cement-gypsum panel with a 2% fiber content achieved the highest flexural strength of 38.577 MPa. According to the experiment's findings on its flexural strength and physical characteristics, abaca fiber could serve as reinforcement for cement-gypsum board.