Flexural Strength Of Concrete Research Articles

Experimental investigation of mechanical properties and multi-objective optimization of electronic, glass, and ceramic waste-mixed concrete.

The utilization of waste from various sources plays an important role in minimizing environmental pollution and civil construction costs. In this research, the mechanical properties of concrete were studied by mixing electronic waste (EW), glass powder (GW), and ceramic tile waste (CW). The effects of weight percentages of EW, GW, and CW are considered to investigate improvements in mechanical properties such as compressive strength (CS), split tensile strength (STS), and flexural strength (FS) of concrete. Taguchi analysis has been applied to predict the optimum composition of waste mixing percentages. The Multi-Objective Optimization Ratio Analysis (MOORA) techniques are applied to estimate the optimum composition of mixing wastes for maximizing the CS, STS, and FS of concrete. It was observed that 10 wt.% of EW, 15 wt.% of GW, and 30 wt.% of CW are predicted as the optimal mixing combinations to obtain a maximum compressive strength of 48.763 MPa, a split tensile strength of 4.178 MPa, and a flexural strength of 7.737 MPa, respectively. Finally, the predicted optimum waste-mixed weight percentages were used to examine the microstructure and various elements in the concrete using SEM and XRD analysis. When compared to conventional concrete, the optimum waste-mixed concrete has improved its compressive strength (38.453%), split tensile strength (41.149%), and flexural strength (36.215%).

Experimental research and theoretical prediction on mechanical properties for recycled GFRP fiber reinforced concrete

Recycled GFRP fiber has increasingly been reused in concrete, necessitating an improvement in its recycling process and an investigation into its effects on the mechanical properties of concrete to achieve higher recycling values. To this end, this study proposed a novel GFRP recycling method that integrates mechanical recycling, water-vibratory separation, and secondary sieving to efficiently remove impurities from GFRP waste. Three different sizes of recycled GFRP fibers (SF, MF, and LF) were sorted from decommissioned GFRP wind turbine blades using the novel recycling method, and their effects of on the mechanical properties of concrete were investigated. The results show that all three types of recycled GFRP fibers increase the strength and toughness of concrete. With equivalent fiber content, the largest recycled GFRP fiber (LF) yields the most substantial reinforcement effect on the mechanical properties of concrete. Specifically, incorporating 1.0 % LF increases the compressive strength, splitting tensile strength, and flexural strength of concrete by 14.0 %, 16.8 %, and 37.0 %, respectively, while also increasing flexural toughness by 2.9 times. In addition, the mechanical properties of recycled GFRP fiber reinforced concrete were theoretically analyzed in this study, and two strength prediction models for recycled GFRP fiber reinforced concrete were established to achieve rapid prediction of concrete strength.

A novel bio-based water reducer for concrete application: Facile process and techno-economic analysis of xylonate bioproduction from lignocellulosic residues

The xylonate was bioproduced directly from lignocellulosic residues, and the application properties of crude xylonate powder were investigated with a promising potential as a bio-based concrete water reducer. The overall integrated process was evaluated on the view of mass balance and techno-economic analysis using Aspen Plus modeling. 56 g/L of calcium xylonate (XA-Ca) can be obtained within 8 h from acidic corncob hydrolysate (ACH) at a 100 % yield with the whole-cell catalysis of Gluconobacter oxydans. At the addition of 0.2 wt% in the dry concrete content, XA-Ca powder and sodium xylonate powder prepared from pure xylose and ACH could reduce water used in concrete by 15 %, 14 %, 13 %, and 13 %, respectively. XA-Ca from ACH led to a 33% increase in concrete compressive strength and a 24% increase in concrete flexural strength at day 7 compared to the blank group. The techno-economic analysis showed the minimum XA-Ca powder price to be $ 0.806/kg which can be economically feasible. This study provides a practical and economical process prototype for the industrial concrete water reducer application of novel bio-based xylonate produced from lignocellulosic residues.

Nanomaterials in concrete: Enhancing strength and durability

Carbon nanotubes (CNTs) have received great attention for their applications in concrete due to their unique properties such as high strength, flexibility, and electrical conductivity. This study aims to investigate the effect of adding carbon nanotubes on the energy combination of the material. Concrete samples were prepared with different concentrations of carbon nanotubes and their mechanical properties were measured and compared with control samples without carbon nanotubes. The results show that the addition of carbon nanotubes increases the compressive and flexural strength of concrete. The findings suggest that incorporating carbon nanotubes into concrete could be a good way to improve concrete's mechanical properties and improve its performance in construction. Compared with white cement M20 samples aged 7, 14 and 28 days. The 28day maximum strength is stated below for 0.0045 wt.% SWCNT and MWCNT and 0.0030 wt.% SWCNT and MWCNT. It was determined that nanocomposites containing a lower proportion of long MWCNTs had properties comparable to nanocomposites containing a higher proportion of short MWCNTs. Many of the walls of the carbon nanotubes reach microcracks, indicating that the carbon nanotubes are cracked and pulled out. Besides the compression test, we also calculated the slit tensile strength by adding different percentages of carbon nanotubes. The usage percentage increased for 0.0015% MWCNTs and 0.0030% and 0.0045% SWNTs.

Development of geopolymer-based lightweight high-strength concrete and properties at different temperatures

In the current study, a green and high-strength lightweight concrete is developed. Geopolymer-based lightweight concrete (G-LWC) is an innovative green building material that combines the advantages of geopolymers and lightweight concrete. Building upon existing research, to achieve low density, a lightweight aggregate, expanded glass powder (EGP), is used, resulting in the development of geopolymer-based lightweight high-strength concrete (G-LWHC) with a compressive strength exceeding 100 MPa. The influence of different EGP content and fiber admixtures on its density and mechanical properties is also studied, and its performance after exposure to high temperatures is analyzed from both micro and macro perspectives. The research results indicate that the incorporation of EGP significantly reduces the concrete density while also decreasing its compressive strength. G-LWHC exhibits significant temperature-induced ductility, with RT,150D increasing by 142.80% and 258.02% after exposure to 600 °C and 800 °C, respectively, compared to room temperature conditions. The addition of fibers has the most notable impact on improving the concrete's flexural strength. The developed G-LWHC exhibits characteristics of being lightweight, high-strength, and resistant to high temperatures, maintaining residual strength even after exposure to 800 °C.

Experimental Analysis on Partial Replacement of Cement by Glass Powder and Using of Steel Fiber

Abstract: Concrete consists of fine aggregate, coarse aggregate, water, and optional admixtures, such as Portland cement or another hydraulic cement. Because of its massive resource consumption, the concrete industry poses a serious danger to the sector's long-term viability. The concrete industry is struggling in part because of concerns about the environment and the economy. Many studies are currently being conducted on the utilisation of waste materials like Pulverised Fly Ash (PFA) and Ground Granulated Blast Furnace Slag (GGBS) as supplemental cementitious materials. Similar to PFA and GGBS, waste glass powder can be used to partially substitute cement during the hydration reaction. To some extent, waste glass can substitute cement in concrete and contribute to strength development if it is ground to a very fine powder and demonstrates pozzolanic properties due to its high SiO2 content. This research examined the Compressive, Tensile, and Flexural strengths of concrete that had been aged for up to 60 days with concrete that had been partially replaced with Glass Powder at percentages ranging from 0% to 40%. The aggregate test findings suggest that Waste Glass Powder could be used as a suitable cement replacement in construction projects. Fibre reinforced concrete (FRC) is a composite building material made from small, discontinuous fibres that are randomly distributed throughout the concrete part. Steel, glass, and polymer fibres, as well as fibres originating from natural sources, are the most common types of fibre used in cement-based composites. The tendency of fibres to be more closely spaced than traditional reinforcing steel bars makes them more effective at preventing cracking. It's important to note that fibre is not a suitable replacement for steel bars when reinforcing concrete.

Effect of Cockle Shell as Coarse Aggregates Replacement on Mechanical Properties of Concrete

Gravel is a natural raw material used in concrete mixtures. However, more of this scarce resource was used, which reduced the amount of gravel-based coarse aggregates that could be produced. As a result, efforts to preserve natural coarse aggregates for future generations were critical. So, an innovation to replace this natural coarse aggregate was required. The dumping of cockle shell waste by the cockle trade emits a stinking smell and pollutes the environment. This study investigates the density, compressive, splitting tensile and flexural strengths of concrete containing cockle shell as a coarse aggregate substitute. Four concrete mixes were prepared by integrating diverse contents of cockle shell as 0%, 10%, 20% and 30% partial replacement of coarse aggregates by weight of gravel. Concrete becomes less dense as a large amount of cockle shell is integrated. Utilization of cockle shell up to 10% enhances the compressive strength of concrete. However, increasing the amount of cockle shell by up to 30% can improve the splitting tensile and flexural strength of concrete

A Comparative Analysis of Compressive and Flexural Strength in Concrete with Partial Cement Replacement using Waste Glass Powder

This experimental inquiry delves into the evaluation of compressive and flexural strengths in concrete through the utilization of waste glass powder as a partial substitute for cement. Compressive strength is a key metric, indicating the concrete’s ability to effectively support structural axial loads, while flexural strength signifies its capacity to withstand deformation under bending, specifically the maximum tensile stress it can endure without fracturing when subjected to a bending moment. Certain pozzolanic materials have demonstrated the ability to enhance the mechanical strength of concrete when used as a cement replacement, and waste glass powder is among them. To address this, the experimental investigation included the substitution of cement with glass powder at different proportions (0%, 10%, 15%, 17.5%, and 20%) in both cubic and prismatic samples. Compressive strength and flexural strength tests were made following the curing of the samples for 7, 14, and 28 days. The findings indicated that the 17.5% cement replacement level exhibited a 6.07% over-strength for compressive strength and a 6.85% over-strength for flexural strength on the 28th day. However, the 15% replacement showed superior strength compared to a 10% replacement, and the 10% replacement was stronger than a 0% cement replacement. Notably, the 20% cement replacement displayed negative over-strength percentages, specifically -2.42% in compressive strength and -1.42% in flexural strength on the 28th day. This deviation raises concerns about its suitability for use in concrete applications, signifying that a 20% replacement may not be recommended.

ENHANCING CONCRETE FLEXURAL STRENGTH: REPLACING CEMENT WITH FLY ASH AND BRICK KILN DUST

Concrete is now an essential building material for creation of any type of structural elements, including inflexible pavement as well as beams, columns, slabs, bridges, and girders. Cement is the most essential binding component in the manufacture of concrete because, when combined with water, it can bind both Coarse Aggregate (CA) and Fine Aggregate (FEA). The terms (BKD and FA, which have certain binding qualities when mixed with water, are waste products, as indicated by the paper's title. The researcher's objective is to show how FA and BKD mixed in the percentages of 0%, 10%, 20%, 30%, and 40% are used to partially substitute Ordinary Portland Cement (OPC) of 43 grade during the production of M25 grade of concrete mix design and to calculate the Flexural Strength in accordance with Indian Standards (IS). The outcome of this research analysis demonstrates that FA and BKD can be employed in the manufacturing of concrete with the objective of lowering both emissions of greenhouse gases and cement concrete production costs.

Use of recycled concrete and rice husk ash for concrete: A review

The rapid development of populations and the demand in the consumption of concrete is generating the need to produce larger quantities of cement, which brings with it negative effects for the environment. Approximately 0.87 kg of CO2 is produced by the manufacture of cement; In addition, the use of aggregates is generating great concern in the construction industry, due to the costs and the restriction of these. Similarly, the accumulation of construction and demolition waste (RCA) and rice husk ash (RHA) contribute to pollution. Therefore, the objective of this manuscript is to review the literature on the use of RCA and RHA for the elaboration of concrete. For this, indexed articles were used, between the years 2017-2021. The results showed that when 8% RHA is added, the concrete reaches a compressive strength of 70 MPa; as well as, the flexural strength of concrete by adding 50% RCA + 1.50% basalt microfibers was increased by 29.44%. On the other hand, when RHA is added by 15% it reaches a compressive strength of 48.8 MPa; in turn, the mechanical performance at bending with 10% seashell by fine aggregate and 20% RHA by cement, reached a resistance of 65 MPa. Concluding, that the behavior of concrete undoubtedly depends on the proportions of either RCA or RHA; however, the percentages must be no more than 8% and 15% respectively.

Effect of Bacillus Subtilis Bacteria on The Mechanical Properties of Corroded Self-Healing Concrete

Reinforced concrete has a weakness for corrosion which can cause the concrete to crack and the concrete structure to fail. To overcome this problem, a self-healing concrete method is needed that can close cracks and inhibit the rate of natural corrosion. Bacillus subtilis as a self-healing agent in concrete has been proven to be able to increase the compressive strength and flexural strength of concrete. The method used in this research is to add bacterial hydrogel encapsulation to concrete with a variation of 0%; 0.1%; 0.6%; and 1.5% by weight of sand. The test object is a reinforced concrete beams and cylindrical concrete with compressive design strength of 30 MPa. The concrete specimens will go through a series of tests, such as corrosion acceleration tests using DC power supply, self-healing tests by visual observation, flexural strength, ductility, stiffness, and compressive strength tests using Universal Testing Machine (UTM). From the test results, it was found that the addition of 0.1% bacterial encapsulation variation was the optimum value for increasing the mechanical properties of self-healing concrete and reduce the corrosion rate on self-healing concrete.

Enhancing Concrete Properties with Agave Americana Fiber Reinforcement.

This research article explores the potential of using agave Americana fibers (AAFs) to enhance the physical and mechanical properties of concretes. The study investigates the impact of AAFs on concrete mix proportions in detail. Different concrete compositions are systematically created by integrating AAFs into them. The chemical structure, crystallinity, morphology, and tensile strength of extracted AAFs are examined, revealing a low cellulose content and a crystallinity index of around 41.34%. The microstructural analysis highlights the rough surface morphology of the extracted AAFs. The research also evaluates how AAFs affect concrete density, water uptake, and flexural and compressive strengths across various mixtures. The results show that incorporating AAFs in a horizontal position can increase the flexural resistance by up to 99% and the compressive resistance by up to 86% without chemical reactions occurring with mud-lime concrete. However, it is worth noting that using AAFs with cement can affect fiber durability due to the alkaline environment. As the alkali concentration increases, the fiber mechanical resistance decreases. Therefore, it is recommended to use AAFs with noncement concrete for improved sustainability and durability. Overall, this study advances our understanding of eco-friendly and resilient concrete materials.

Mechanical properties of sustainable concrete containing powdery ladle furnace slag from different sources

A suitable content of powdery Ladle Furnace Slag (LFS) has to be selected to balance its hydraulic and expansive properties when added to concrete. In this study, the performance of concrete containing two powdery LFS is studied: H-type LFS, stabilized before use, and N-type LFS, used in its original state. Lower expansiveness was observed in the H-type LFS, and strength development was assisted by the formation of calcium-silicate-hydrates. Therefore, it increased the modulus of elasticity, the splitting tensile strength, and the flexural strength of concrete. Higher hydraulicity and expansiveness were found in the N-type LFS, which improved compressive-behavior-related properties up to a content of 10% but reduced tensile-related properties. These aspects were confirmed through scanning electron microscopy. In general, the H-type LFS improved the mechanical properties and carbon footprint of concrete, and its use is recommended in a multi-criteria approach, although the difference between both LFS was only statistically significant at advanced ages.

A Study on Enhancing the Properties of Geopolymer Concrete Using Hybrid Fibers

Alkali is present in significant quantities in geopolymer concretes. Due of this, their ductility and flexural strength are also low. The flexural strength of concrete is enhanced by the addition of fibers. Flexural strength has been a challenge for geopolymer concretes, thus researchers have tried using fibers to strengthen them. On the other hand, geopolymer concretes have never before utilized hybrid fibers. This study is an effort to incorporate hybrid fibers in geopolymer concrete to prevent its brittle fracture. Experiments are conducted to learn more about the geopolymer concrete's different mechanical characteristics, and then the settings are fine-tuned. Mechanical qualities of geopolymer concrete are improved by determining the optimal molarity of sodium hydroxide, the optimal ratio of sodium silicate to sodium hydroxide, and the optimal proportion of addition of fibers.

Impact of Incorporating Rice Husk Ash (RHA) into Recycled Concrete Aggregates (RCA) on the Compressive and Flexural Strength of Concrete

This study aimed to assess the strength characteristics of concrete using Recycled Concrete Aggregates (RCA) as full replacement to coarse aggregates and Rice Husk Ash (RHA) as an admixture. The concrete samples were subjected to curing for 7, 14, and 28 days. Specifically, the study evaluated the workability of freshly mixed concrete and compared the compressive and flexural strength with RCA and RHA to normal concrete. Four different treatment mixtures were used with three replicates with varying ratio of RHA to cement: Treatment 1 (1 cement: ¾ RHA), Treatment 2 (1 cement: ½ RHA), Treatment 3 (1 cement: ¼ RHA). In all cases, RCA completely replaced natural coarse aggregates. The results indicated that the slump which measures the workability of the RCA concrete met the desired standard specifications. Additionally, the RCA concrete with the highest RHA content obtained the highest compressive and flexural strength on the 28th day test but did not exceed the control. Furthermore, the study revealed that the concrete specimens could handle maximum loads for flexure rather than compression load.

The Effect of 0.8% Polyethylene Terephthalate Plastic Waste Substitution on the Flexural Strength on K-175 Concrete

The use of plastics in daily life continues to increase in a variety of uses. One of the most commonly used plastic that is difficult to decompose is Polyethylene Terephthalate (PET) plastic. In recent years, such as the construction industry, has been trying to reuse the waste as construction material. Therefore, this research aims to contribute by exploring the effect of PET plastic fiber substitution as fine aggregate on the flexural strength of concrete. PET plastic fibers were used at 0.8% as partial replacement of fine aggregates and then chopped to a size of 5 cm long, 1-3 mm wide. The test results indicate that concrete containing 0.8% PET plastic fiber as a substitution of fine aggregate has a higher flexural strength value of 4.32% which is better than normal concrete. Therefore, using recycled PET fiber in concrete is needed as an eco-friendly and sustainable construction material in the future in order to minimize PET plastic waste and replace it as a concrete constituent material.

Experimental and Statistical Study of Flexural Strength in Concrete using Novel Kaolinite Coal

The purpose of this research is to measure the flexural strength of both traditional and newly modified concrete beams with kaolinite coal added. Two sets of eighteen samples each were ready for the data collection. Two sets of specimensare prepared: 18 specimens of one set using modified concrete that has been treated with kaolinite coal, and the other set of 18 specimens using traditional concrete beams. The preparation and examination of the samples involved the use of flexural strength test equipment. The beam specimen size was taken as 100 x 100 x 500mm. The SPSS software version 29 has been utilized to conduct the independent sample T-test. The statistical analysis included Levene's test for equality of variances and a t-test for equality of means to assess the flexural strength of two groups. Levene's test revealed a significant difference in variances between the groups (F=2.909, p=0.097). Subsequently, the t-test assuming equal variances indicated a highly significant difference in means (t=-16.954, df=34, p=0.000). The mean difference in flexural strength was -1.43578, with a standard error of 0.08469 and a 95% confidence interval ranging from -1.60788 to -1.26367. The t-test assuming unequal variances corroborated the significant difference in means (t=-16.954, df=29.822, p=0.000), with a consistent mean difference and confidence interval. The modified concrete beam sample with kaolinite coal added has a mean flexural strength of 4.75 N/mm2, while the standard concrete beam sample has a mean flexural strength of 2.73 N/mm2.

Investigating the usability of Kevlar and steel fibers as a hybrid in concrete pavements

In this study, the hybrid usage of Kevlar and steel fiber in concrete pavements was investigated. For this purpose, the concrete was designed using the water/binder ratio (0.40, 0.45, 0.50), silica fume (instead of cement 0, 5, 10%), Kevlar fiber (0 gr/m3, 500 gr/m3, 1000 gr/m3) and steel fiber (0 gr/m3, 500 gr/m3, 1000 gr/m3). Taguchi method was used as the experimental design, and optimum levels of parameters were determined for 28-days compressive strength, flexural strength, and toughness. According to the experiments and observations, the positive effect of Kevlar fiber upon energy absorption capacity (toughness), compressive and flexural strength of concrete was determined. Using only Kevlar fiber increasing up to 5.1% in compressive strength and up to 14.5% in flexural strength were observed. Considering the obtained results, Kevlar was noticed as a possible recycling material to be introduced into the economy by adding concrete.

Experimental and Statistical Study of Flexural Strength in Concrete using Novel Kaolinite Coal

The purpose of this research is to measure the flexural strength of both traditional and newly modified concrete beams with kaolinite coal added. Two sets of eighteen samples each were ready for the data collection. Two sets of specimensare prepared: 18 specimens of one set using modified concrete that has been treated with kaolinite coal, and the other set of 18 specimens using traditional concrete beams. The preparation and examination of the samples involved the use of flexural strength test equipment. The beam specimen size was taken as 100 x 100 x 500mm. The SPSS software version 29 has been utilized to conduct the independent sample T-test. The statistical analysis included Levene’s test for equality of variances and a t-test for equality of means to assess the flexural strength of two groups. Levene's test revealed a significant difference in variances between the groups (F=2.909, p=0.097). Subsequently, the t-test assuming equal variances indicated a highly significant difference in means (t=-16.954, df=34, p=0.000). The mean difference in flexural strength was -1.43578, with a standard error of 0.08469 and a 95% confidence interval ranging from -1.60788 to -1.26367. The t-test assuming unequal variances corroborated the significant difference in means (t=-16.954, df=29.822, p=0.000), with a consistent mean difference and confidence interval. The modified concrete beam sample with kaolinite coal added has a mean flexural strength of 4.75 N/mm2, while the standard concrete beam sample has a mean flexural strength of 2.73 N/mm2.

The comparative study of epoxy and bacterial injections for cracked concrete beam flexural strength

Cracks in concrete beams can significantly affect the performance of reinforced structures. To repair cracks in concrete, Traditional crack repair methods typically involve epoxy injection, but studies have suggested that epoxy may not fully restore the original strength. Therefore, concrete structure repair requires the development of new and more efficient materials. This study focuses on investigating the potential of Bacillus megaterium, a bacterium known for its self-healing properties in concrete. This bacterium has the capability to precipitate minerals like calcium carbonate, which can fill the cracks and increase the strength of concrete. Testing is carried out on reinforced concrete beams with existing cracks, sized at 100 mm x 100 mm x 500 mm. The specimens are divided into two groups, one repaired with epoxy injection and the other with bacterial injection, with varying additions of 10% and 15%. The research results show that the injection process with the addition of 15% bacteria is able to restore approximately 99.72% of the initial strength of the concrete beams. The results of this research contribute to the development of improved repair techniques that can restore the flexural strength of cracked concrete beams and extend the service life of concrete structures.