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Gautam, Nitin, Monica Kotwal, Sunny Sharma, Anupama Gaur, Rimsha Ahmed i Shivani Jandial. "Invitro Comparative Analysis of the Flexural Strength of 4 Different Commercially Available Provisional Materials Used in Fixed Partial Dentures – An Original Research". Annals of International Medical and Dental Research 9, nr 3 (czerwiec 2023): 263–68. http://dx.doi.org/10.53339/aimdr.2023.9.3.31.
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Background: Provisional Prosthesis in fixed partial dentures are subjected to Flexure under stress. Selection of appropriate material for fabrication of Provisional is of utmost importance as the Provisional prosthesis has to remain in function till definitive prosthesis is delivered. Material & Methods: Bar type specimens of four different commercially available brands for provisional restorations fabricated according to ADA specification No. 27 and immersed in artificial saliva. The specimens were fractured under 3-point loading test. Results: The flexural strength ranged between 60 to 110 Mpa. BisGMA Auto polymerizing composite resin from Dentsply Caulk shows the highest flexural strength. Conclusion: Within the limitations of this study, the flexural strengths were material specific rather than category one. The BisGMA composite based resin shows significantly higher flexural strength over other materials.
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Kato, Daisuke, Daisuke Sato i Tadashi Takamatsu. "Effects of opening location on flexural behavior of RC columns with sidewalls". Bulletin of the New Zealand Society for Earthquake Engineering 50, nr 4 (31.12.2017): 547–54. http://dx.doi.org/10.5459/bnzsee.50.4.547-554.
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Practical use of secondary walls such as sidewalls is common because the contributions of secondary walls for stiffness or strength have been recognized. In 2016, “AIJ Standard for Lateral Load-carrying Capacity Calculation of Reinforced Concrete Structures” was published as a draft by Architectural Institute of Japan. In this standard new equations for columns with side walls were proposed. From this viewpoint, the authors have conducted static loading tests of flexurally controlled RC column specimens with single opening in the sidewall, to investigate the effects of openings on strength and deformation capacity of RC columns with a side walls. In this paper, the limitations on location of openings inside sidewalls to avoid their effects on flexural strength and deformation capacity are examined using design equations for flexural strength based on full plastic moment of the column and sidewall. The test results indicate that the proposed limitation line on location of openings to avoid their effects for flexure could be effective for practical design.
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Filiatrault, André, Danilo D'Aronco i René Tinawi. "Seismic shear demand of ductile cantilever walls: a Canadian code perspective". Canadian Journal of Civil Engineering 21, nr 3 (1.06.1994): 363–76. http://dx.doi.org/10.1139/l94-039.
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During severe earthquakes, ductile flexural walls are expected to exhibit inelastic flexural behaviour while other brittle deformation mechanisms, such as shear, should remain elastic. The philosophy of the Canadian seismic provisions for flexural walls is based on the assumption that the force reduction factor is applicable to both flexure and shear. If the bending moments are limited because of the flexural strength of a wall, then the shear forces are considered to be limited by the same ratio. Recent case studies have not confirmed this philosophy. Brittle shear failures in walls are still possible even if their shear strengths are established by the Canadian standards. This paper presents an analytical investigation on the shear demand of ductile flexural walls designed for three different seismic zones in Canada. For each zone, an ensemble of code compatible historical earthquake ground motions is identified. The shear demand of each structure, under each earthquake record, is obtained by nonlinear time-history dynamic analyses. In 77% of the cases, the computed dynamic shear demand is higher than the current code shear strength. To address this issue, a force modification factor for shear, different from the one for flexure, is suggested for the Canadian code. Key words: earthquake, seismic response, shear walls.
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Z. A. Siddiqi, M. M. Kaleem, M. Jawad, A. Ajwad i M. Usman. "Comparison of Mechanical Properties of Normal & Polypropylene Fiber Reinforced Concrete". Scientific Inquiry and Review 2, nr 1 (31.01.2018): 33–47. http://dx.doi.org/10.32350/sir/21/020105.
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Concrete is the most commonly used construction material in the world. However, normal weight concrete shows less resistance to flexure. This research dealt with the technique to improve material efficiency in flexure as well as in compression, using polypropylene fibers. Different samples of concrete were prepared containing different dosages of polypropylene fibers (0.1%, 0.2%, 1% and 2% of the total concrete volume). The samples were then tested in compression and flexure, after 7, 14 and 28 days. The experimental investigation showed that the fibers increase the flexural strength of concrete in elastic range, when used in a specific limit. Maximum efficiency from the material was obtained at 0.2% dosage of fibers. Below and above this percentage the flexural and compressive strengths start decreasing. The experimental results also confirmed that with the gradual increase in polypropylene content the water absorption of concrete increases.
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TSUDA, Keigo, Masae KIDO i Masanori KOBAYASHI. "APPROXIMATE ANALYSIS OF FLEXURAL-TORSIONAL BUCKLING STRENGTH USING FLANGE FLEXURA L BUCKLING STRENGTH". Journal of Structural and Construction Engineering (Transactions of AIJ) 77, nr 678 (2012): 1309–18. http://dx.doi.org/10.3130/aijs.77.1309.
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Ozkir, Serhat Emre, Burak Yilmaz, Server Mutluay Unal, Ahmet Culhaoglu i Isin Kurkcuoglu. "Effect of heat polymerization conditions and microwave on the flexural strength of polymethyl methacrylate". European Journal of Dentistry 12, nr 01 (styczeń 2018): 116–19. http://dx.doi.org/10.4103/ejd.ejd_199_17.
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ABSTRACT Objective: The objective of this study is the effect of different heat polymerization conditions on the strength of polymethyl methacrylate (PMMA) resin base is unknown. Distinguishing one method that provides improved mechanical properties may be beneficial to the clinical success of complete and partial dentures and overdentures. The purpose of this study was to evaluate the effect of different polymerization methods on the flexural strength of a dental PMMA resin. Materials and Methods: Forty PMMA specimens (64 mm × 10 mm × 4 mm) were prepared with 4 different polymerization methods (n = 10); heat polymerization at 74°C for 9 h, at 100°C for 40 min, and with 620 kPa pressure at 100°C for 20 min. The remaining group of specimens was microwave polymerized at 180 W for 6 min. All specimens were thermocycled at 5°C and 55°C for 5000 times. Three-point flexure test was used to measure the flexural strength of specimens. One-way ANOVA and Tukey Honestly Significant Difference were applied to analyze the differences in flexural strengths (⍺ = 0.05). Results: The flexural strength of heat-polymerized groups was similar. The flexural strength of microwave polymerized group was significantly different and lower than the other groups (P < 0.05). Conclusion: Polymerizing conventional heat-polymerizing PMMA resin with microwave energy resulted in a significant decrease in flexural strength. The results of this study suggest that clinicians may benefit from using heat polymerization when processing PMMA denture bases instead of microvawe polymerization when tested brand is used.
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Zheng, Wan Hu, Li Juan Li i Feng Liu. "The Compressive and Flexural Deformation of Rubberized Concrete". Advanced Materials Research 168-170 (grudzień 2010): 1788–91. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1788.
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The deformation of rubberized concrete under uniaxial compression and three-point flexure is studied in this paper by test, and the load-deflection curves and load-strain curves under three-point flexure are obtained. Three rubberized concrete, with 5%, 10% and 15% rubber contents, were tested. The test results show that rubber powder influences the compressive strength and flexural strength of concrete. The greater of the rubber dosage, the greater of the strength decreasing of concrete. The decline of compressive strength is greater than flexural strength, the ratio of flexural strength to compressive strength of rubberized concrete is 1.08, 1.16, 1.26 times of the normal concrete for three different rubber contents respectively. And the ultimate tensile strain of rubberized concrete is 1.62, 2.25, 2.80 times of the normal concrete respectively. The addition of rubber improved the toughness and deformation ability of the normal concrete.
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Hu, Chen, Long Quan Shao, Lin Lin Wang, Shan Yu Zhou i Jun Ai. "Flexure Strength and Elastic Modulus of Four Types of Dental Fiber Posts". Key Engineering Materials 519 (lipiec 2012): 269–72. http://dx.doi.org/10.4028/www.scientific.net/kem.519.269.
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Objective. To investigate the flexure strengths and elastic modulus of four types of dental fiber posts. Methods. The flexure strengths of ParaPost Taper Lux, Tenax Fiber White, Luxa Post and Rebilda Post fiber post were measured. The rupture modes were analyzed with SEM. Results. There was no significant difference between ParaPost Taper Lux (591.47±35.15MPa) and Rebilda Post (614.67±58.36MPa) in flexure strength (P>0.05), and Tenax Fiber White (846.62±71.15MPa) had significantly higher flexure strength than the other groups. There was no significant difference between Tenax Fiber White (23.93±2.14GPa) and Luxa Post (22.67±1.39GPa) in elastic modulus (P>0.05), and Tenax Fiber White and Luxa Post had significantly lower elastic modulus than other groups. It could be observed by transverse SEM that the combine of fiber and resin was even and compact and plenty of resin fragment adhered to the surface of fiber in Tenax Fiber White group, multitudinous cracks were observed by lengthwise SEM. Conclusion. The flexural properties and rupture modes of four kinds of dental fiber posts were significantly different.
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Irie, Masao, Masahiro Okada, Yukinori Maruo, Goro Nishigawa i Takuya Matsumoto. "Shear Bond Strength of Resin Luting Materials to Lithium Disilicate Ceramic: Correlation between Flexural Strength and Modulus of Elasticity". Polymers 15, nr 5 (23.02.2023): 1128. http://dx.doi.org/10.3390/polym15051128.
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This study investigates the effect of the curing mode (dual-cure vs. self-cure) of resin cements (four self-adhesive and seven conventional cements) on their flexural strength and flexural modulus of elasticity, alongside their shear bond strength to lithium disilicate ceramics (LDS). The study aims to determine the relationship between the bond strength and LDS, and the flexural strength and flexural modulus of elasticity of resin cements. Twelve conventional or adhesive and self-adhesive resin cements were tested. The manufacturer’s recommended pretreating agents were used where indicated. The shear bond strengths to LDS and the flexural strength and flexural modulus of elasticity of the cement were measured immediately after setting, after one day of storage in distilled water at 37 °C, and after 20,000 thermocycles (TC 20k). The relationship between the bond strength to LDS, flexural strength, and flexural modulus of elasticity of resin cements was investigated using a multiple linear regression analysis. For all resin cements, the shear bond strength, flexural strength, and flexural modulus of elasticity were lowest immediately after setting. A clear and significant difference between dual-curing and self-curing modes was observed in all resin cements immediately after setting, except for ResiCem EX. Regardless of the difference of the core-mode condition of all resin cements, flexural strengths were correlated with the LDS surface upon shear bond strengths (R2 = 0.24, n = 69, p < 0.001) and the flexural modulus of elasticity was correlated with them (R2 = 0.14, n = 69, p < 0.001). Multiple linear regression analyses revealed that the shear bond strength was 17.877 + 0.166, the flexural strength was 0.643, and the flexural modulus was (R2 = 0.51, n = 69, p < 0.001). The flexural strength or flexural modulus of elasticity may be used to predict the bond strength of resin cements to LDS.
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Zhang, Lijuan, Jun Zhao, Cunyuan Fan i Zhi Wang. "Effect of Surface Shape and Content of Steel Fiber on Mechanical Properties of Concrete". Advances in Civil Engineering 2020 (21.07.2020): 1–11. http://dx.doi.org/10.1155/2020/8834507.
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Steel fiber reinforced concrete (SFRC) has gained popularity in the last decades attributed to the improvement of brittleness and low tensile strength of concrete. This study investigates the effect of three shapes of steel fibers (straight, hooked end, and corrugated) with four contents (0.5%, 1%, 1.5%, and 2%) on the mechanical properties (compression, splitting tension, shear, and flexure) of concrete. Thirteen groups of concrete were prepared and investigated experimentally. Test results indicated that steel fiber had significant reinforcement on mechanical properties of concrete. When the steel fiber content increases from 0.5% to 2.0%, the compressive strengths increase about 4–24%, splitting tensile strengths increase about 33–122%, shear strengths increase about 31–79%, and flexural strengths increase about 25–111%. Corrugated steel fiber has the best reinforced effect on strength of SFRC, hooked end steel fiber takes the second place, and straight steel fiber is the least. Calculated formulas of compressive, splitting tensile, shear, and flexural strengths were established with consideration of the bonding properties between concrete and steel fiber. Influence factors of steel fiber αf and concrete matrix strength αc were put forward and determined by regression analysis of experimental data. Calculated results agree well with the experimental results.
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Sisman, Mehmet, Egemen Teomete, Jale Yanik, Ugur Malayoglu i Gozde Tac. "The effects of apricot kernel shell nanobiochar on mechanical properties of cement composites". Cement Wapno Beton 28, nr 1 (6.06.2023): 2–15. http://dx.doi.org/10.32047/cwb.2023.28.1.1.
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Valorization of agricultural wastes is important both economically and environmentally. This study aimed to investigate the use of biochar as a filler to improve the mechanical properties of mortar and to help sequestrate CO2. The biochar was produced by pyrolysis of apricot kernel shell at 500 °C. Nanobiochar particles with dimensions less than 500 nm were obtained by high-energy ball milling process. Scanning electron microscope was used for determining the morphology of nanobiochar. The nanobiochar at different volume percentages [0.00-0.04-0.06-0.08-0.12-0.15%] was added to mortar. The mortar was casted into 40x40x160 mm molds. After water curing at 20°C for 28 days, compressive strength and flexural strength tests were performed. The mixture containing 0.04% nanobiochar by volume had an increase in flexural and compressive strengths by 5% and 15% respectively, while its fracture energies for flexure and compression increased by 98% and 38% respectively compared to the reference mortar. Furthermore, the mixture having 0.12% volume had an increase in flexural and compressive strengths by 32% and 11%, respectively, while the increase in fracture energies for flexure and compression was 52% and 25%, respectively, compared to the reference mortar. The mechanisms of nanobiochar effect on flow, strength, and fracture energy were enlightened. The nanobiochars bridge the cracks, divert the cracks, act as hydration nucleation sites, enhance the matrix by its porous structure, and developed internal curing that led to increase in strength and fracture energy. This study suggests that the biochar produced from the apricot kernel shell has the potential to be used as a carbon sequestering mixture to improve performance of mortar and thereby utilizing waste as a construction material, contributing to the economy and environment.
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Imam, Mahmoud, Lucie Vandewalle i Fernand Mortelmans. "Shear – moment analysis of reinforced high strength concrete beams containing steel fibres". Canadian Journal of Civil Engineering 22, nr 3 (1.06.1995): 462–70. http://dx.doi.org/10.1139/l95-054.
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This paper concerns the incorporation of steel fibres in singly reinforced high strength concrete beams without stirrups failing under the combined effect of flexure and shear. A new equation for predicting the shear strength of reinforced high strength concrete beams is developed. This equation shows a good correlation with own test data of 16 reinforced high strength concrete beams with and without steel fibres and numerous published experimental data for beams with concrete compressive strength up to 140 MPa. The flexural capacity of reinforced high strength concrete beams is also investigated. The existing ACI method for predicting the flexural strength of steel fibre concrete composites is slightly modified to be applicable for high strength concrete. Based on the proposed equations, an analytical model is developed for predicting the relative flexural capacity, i.e., the ratio of the moment with shear interaction to the pure flexural moment. Key words: high strength concrete, steel fibre, shear strength, flexural strength, stirrups, web reinforcement.
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Hussain, Shaik, i Jitendra Singh Yadav. "Mechanical and Durability Performances of Alkali-resistant Glass Fiber-reinforced Concrete". Jordan Journal of Civil Engineering 17, nr 2 (1.04.2023): 231–46. http://dx.doi.org/10.14525/jjce.v17i2.06.
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Concrete, being the most widely used construction material in the world, lacks strength in direct tension and flexure. Attempts to reinforce concrete in tension include the use of steel rebars to strengthen the tensile side of concrete as well as the use of discrete fibers as a reinforcing medium. The study conducted in this manuscript details the effects of including alkali-resistant glass fibers in concrete. Mechanical strength, such as strength in compression and flexure, chord modulus of elasticity and bond pull-out strength, have been measured along with porosity and resistance to accelerated carbonation. Five different water to binder ratios in a range of 0.4 to 0.6 had been used to prepare the design mix proportions. The optimum fiber dosage was found to be 1.5% by weight of cement used. The same had been adopted in the design mix proportions. The average increase in compressive strength and flexural strength was 13% and 28%, respectively. Alkali-resistant glass fiber concrete showed less resistance to carbonation when compared to control mix. Results indicate that glass fibers play a predominant role in providing flexural strength to concrete. The pull-out strength of fiber was added to extra post-cracking flexural strength. The inclusion of alkali-resistant glass fibers imparted a maximum addition of 44% increase in the flexural strength compared to control concrete. The inclusion of alkali-resistant glass fibers in concrete paves the way for a leaner mix and eradicates the possibility of congestion of steel reinforcement for certain structures. KEYWORDS: Alkali-resistant glass fibers, Accelerated carbonation, Bond strength, Compressive strength, Flexural strength.
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Hanggara, ST., MT, Ikrar. "PEMANFAATAN LIMBAH BUBUT BESI PADA BETON SERAT DITINJAU DARI KUAT TEKAN DAN KUAT LENTUR". PROKONS Jurusan Teknik Sipil 13, nr 2 (16.01.2020): 93. http://dx.doi.org/10.33795/prokons.v13i2.194.
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The practice of steel lathing by students of Mechanical Engineering State Polytechnic of Malang produces an abundant amount of steel fiber waste. In this research steel fiber was utilized to substitute coarse aggregate in fiber concrete mixture. The purpose of this research is to find out the compressive and flexure strengths of fiber concrete carried out at Material Laboratory Civil Engineering Politeknik Negeri Malang, and to estimate the cost. The required data were of the results of coarse aggregate and fine aggregate tests, and physical cutting of steel lathing waste. Mix design concrete referred to SNI 03-2834-2000. Compressive strength test used 54 cylindrical specimens of Ø15 x 30cm varied at 0%, 5%, and 10% substitutions. Tests were carried out on concrete aged 7, 14, and 28 days. The flexural strength test used 6 beam specimens of 15 x 15 x 60cm varied at 0%, 5%, and 10% substitution. Tests were carried out on 28 days of concrete. The experiment resulted in 39.01 Mpa compressive strength at 0% variation; 24.54 Mpa compressive strength at 5% variation; 21.80 Mpa compressive strength at 10% variation; in 3.87 Mpa flexure strength at 0% substitution; 4.27 Mpa flexure strength at 5% substitution; 4.07 Mpa flexure strength at 10% substitution. The greatest result of flexure strength test occured at 5% variation; at Rp.940,276/m3 at 0% variation and at Rp.938,719/m3 at 5% variation or 0.2 % decrease. Key word : Steel lathe waste, compressive strength, flexure strength
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Merhej, Tammam, Xin Kai Li i De Cheng Feng. "Polypropylene Fiber Reinforced Concrete for Airport Rigid Pavements: Compressive and Flexural Strength". Advanced Materials Research 219-220 (marzec 2011): 1601–7. http://dx.doi.org/10.4028/www.scientific.net/amr.219-220.1601.
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This paper presents the experimental investigation carried out to study the behavior of polypropylene fiber reinforced concrete (PPFRC) under compression and flexure. Crimped polypropylene fibers and twisted polypropylene fiber were used with 0.0%, 0.2%, 0.4% and 0.6% volume fractions. The influence of the volume fraction of each shape of polypropylene fiber on the compressive strength and flexural strength is presented. Empirical equations to predict the effect of polypropylene fiber on compressive and flexural strength of concrete were proposed using linear regression analysis. An increase of 27% in flexural strength was obtained when 0.6% volume fraction of twisted polypropylene fiber was added. It was also found that the contribution of fiber in flexural strength is more effective when twisted fibers were used. The compressive strength was found to be less affected by polypropylene fiber addition.
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Ge, He Yi, Jian Ye Liu, Xian Qin Hou, Hua Shi Liu i Dong Zhi Wang. "Effects of ZrO2 Fiber on the Mechanical Properties of Nano-ZrO2/Al2O3 Ceramic Composite". Advanced Materials Research 455-456 (styczeń 2012): 645–49. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.645.
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The effects of nano-ZrO2, ZrO2fiber and sintering additives on the mechanical properties of Al2O3ceramic composite were investigated by means of orthogonal experimental design. Meanwhile, the effect of environmental temperature on flexural strength of Al2O3ceramic composite was tested. XRD and SEM were used to analyze the microstructure. The results showed that the content of ZrO2fiber had the greatest effect on flexural strength and fracture toughness, followed by the content of nano-ZrO2. Nano-ZrO2made the crystalline grains of Al2O3smaller. ZrO2fiber pulled out from Al2O3matrix could consume energy of crack and increase the flexual strength and toughness of ceramic composite.
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Yeon, Kyu-Seok, Kwan Kyu Kim, Jaeheum Yeon i Hee Jun Lee. "Compressive and Flexural Strengths of EVA-Modified Mortars for 3D Additive Construction". Materials 12, nr 16 (15.08.2019): 2600. http://dx.doi.org/10.3390/ma12162600.
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The compressive and flexural strengths of mortars modified with ethylene-vinyl acetate (EVA) were experimentally investigated for use in three-dimensional (3D) additive construction (3DAC). EVA powder, which is available in a premix type, was employed as an admixture. The test results for the cast specimens showed that, at a curing age of 28 days, the compressive strengths ranged from 32.92 MPa to 43.50 MPa, and the flexural strengths ranged from 12.73 MPa to 14.49 MPa. The compressive and flexural strengths of the printed specimens were relatively lower: 23% to 26% and 3% to 7%, respectively. The compressive strength also decreased and the flexural strength increased when the EVA/cement ratio was increased. The results of the experiment reveal that the EVA-modified mortar had a high rate of strength development early on, making the material advantageous for use in 3DAC. It was determined that the appropriate EVA/cement ratio ranged between 5% and 15%. However, the printed specimens exhibited lower compressive and flexural strengths than did the cast specimens, and the compressive strength decreased as the EVA content was increased. This study provides the compressive and flexural strengths of common EVA-modified mortars, important data for 3DAC applications.
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Abdulsada, Ali ِA, Raid I. Khalel i Kaiss F. Sarsam. "Influence of Minimum Tension Steel Reinforcement on the Behavior of Singly Reinforced Concrete Beams in Flexure". Engineering and Technology Journal 38, nr 7A (25.07.2020): 1034–46. http://dx.doi.org/10.30684/etj.v38i7a.902.
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The requirements of minimum flexural reinforcement in the last decades have been a reason for controversy. The structural behavior of beams in bending is the best way of investigating and evaluating the minimum reinforcement in flexure. For this purpose, twelve singly reinforced concrete beams with a rectangular cross-section of (125 mm) width by (250 mm) height and (1800 mm) length were cast and tested under two-point loads up to failure. These beams were divided into three groups with different compressive strengths (25, 50, and 80 MPa). Each group consists of four beams with different amounts of tension steel reinforcement approximately equal to (0% Asmin, 50% Asmin, 100% Asmin and 150% Asmin), two bar diameters (Ø6 mm and Ø8 mm) were used as the longitudinal tension reinforcement with different yield and ultimate strengths, the minimum amount of reinforcement required is calculated based on ACI 318M-2014 code. The results show that for the reinforced concrete beams, the flexural reinforcement in NSC beams increases the first cracking load and the increment increased with an increasing amount of reinforcement, while for HSC beams the increasing in first cracking load are very little when the quantity of reinforcement less than the minimum flexural reinforcement and increased with the increasing amount above the minimum flexural reinforcement. The equation of ACI 318M-14 code gives adequate minimum flexural reinforcement for NSC and overestimate value for HSC up to (83 MPa), A new formula is proposed for HSC rectangular beams up to (90 MPa) concrete compressive strength by reducing the equation of ACI 318M-14 code for minimum flexural reinforcement by a factor depending on concrete compressive strength.
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Sumarno, Agung, Syafwandi i Kevin Deodatus, leonardus. "EXPERIMENTAL STUDY ON ADDING POLYPROPYLENE FIBER TO COMPRESSIVE STRENGTH AND FLEXURAL STRENGTH OF CONCRETE". Neutron 19, nr 2 (31.01.2020): 62–72. http://dx.doi.org/10.29138/neutron.v19i2.28.
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Concrete is one of the most frequently used materials in the construction world, concrete is generally composed of a mixture of fine aggregate composition. Coarse aggregate, water and cement. However, concrete has a weakness to the ability to withstand the flexural force, today concrete has experienced a lot of innovations, one of which is fiber concrete. Polypropylene fiber is a type of fiber that can be used as an added material in concrete. This research was conducted to determine the effect of adding polypropylene fiber on compressive strength and flexural strength of concrete. Tests in this study were carried out according to SNI (Indonesian national standard) and ASTM (American standard testing and material), from the results of the experiment of adding polypropylene fiber with variations of 0%, 1%, 1.2%, and 1.4% known to have an effect to the compressive strength and flexural strength of concrete. The highest compressive strength and flexure obtained in concrete variations of 1%. By using cylindrical and beam test specimens.
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Islam, Md Toihidul, i Vivek Bindiganavile. "Stress rate sensitivity of Paskapoo sandstone under flexure". Canadian Journal of Civil Engineering 39, nr 11 (listopad 2012): 1184–92. http://dx.doi.org/10.1139/l2012-101.
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This paper evaluates the dynamic flexural response of sandstone from the Paskapoo formation in Alberta. Sandstone prisms were subjected to quasi-static flexure as per ASTM while a drop-weight impact tester was employed to generate stress rates up to 108 kPa/s. Companion testing under quasi-static compression on sandstone cylinders helped establish baseline properties including the compressive strength, elastic modulus, and Poisson’s ratio. It was found that the flexural strength and fracture toughness of Paskapoo sandstone obey stress rate sensitive models developed originally for concrete. However, the fracture toughness was more stress rate sensitive than its flexural strength.
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Kang, Su Tae, Jung Jun Park, Gum Sung Ryu, Gyung Taek Koh i Sung Wook Kim. "Comparison of Tensile Strengths with Different Test Methods in Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC)". Key Engineering Materials 417-418 (październik 2009): 649–52. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.649.
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Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC) is characterized by very high compressive and tensile strength that is about 8 times of ordinary concrete, and high ductility owing to the addition of steel fibers. This paper investigates the relationship existing among the direct tensile strength, flexural tensile strength and splitting tensile strength of UHS-SFRC. Differently from ordinary concrete, it is found that the first cracking strengths in UHS-SFRC obtained through direct tensile test and splitting tensile test are similar, while the strength obtained from flexural tensile test is significantly larger than those from other tests. Based on the experimental results, relationships between the direct tensile strength and flexural tensile strength, between the first cracking strengths in direct tensile test and in flexural tensile test, and between the first cracking strength in direct tensile test and the flexural tensile strength are proposed.
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Irie, Masao, Yukinori Maruo, Goro Nishigawa, Kumiko Yoshihara i Takuya Matsumoto. "Flexural Strength of Resin Core Build-Up Materials: Correlation to Root Dentin Shear Bond Strength and Pull-Out Force". Polymers 12, nr 12 (9.12.2020): 2947. http://dx.doi.org/10.3390/polym12122947.
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The aims of this study were to investigate the effects of root dentin shear bond strength and pull-out force of resin core build-up materials on flexural strength immediately after setting, after one-day water storage, and after 20,000 thermocycles. Eight core build-up and three luting materials were investigated, using 10 specimens (n = 10) per subgroup. At three time periods—immediately after setting, after one-day water storage, and after 20,000 thermocycles, shear bond strengths to root dentin and pull-out forces were measured. Flexural strengths were measured using a 3-point bending test. For all core build-up and luting materials, the mean data of flexural strength, shear bond strength and pull-out force were the lowest immediately after setting. After one-day storage, almost all the materials yielded their highest results. A weak, but statistically significant, correlation was found between flexural strength and shear bond strength (r = 0.508, p = 0.0026, n = 33). As the pull-out force increased, the flexural strength of core build-up materials also increased (r = 0.398, p = 0.0218, n = 33). Multiple linear regression analyses were conducted using these three independent factors of flexural strength, pull-out force and root dentin shear bond strength, which showed this relationship: Flexural strength = 3.264 × Shear bond strength + 1.533 × Pull out force + 10.870, p = 0.002). For all the 11 core build-up and luting materials investigated immediately after setting, after one-day storage and after 20,000 thermocycles, their shear bond strengths to root dentin and pull-out forces were correlated to the flexural strength in core build-up materials. It was concluded that the flexural strength results of the core build-up material be used in research and quality control for the predictor of the shear bond strength to the root dentin and the retentive force of the post.
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Zhao, Y., Feng Lai Wang i Fei Zhu. "The Effects of Applied Axial Stress on Lateral Bearing-Load Capacity for Fully Grouted Reinforced Concrete Masonry Shear Walls". Applied Mechanics and Materials 166-169 (maj 2012): 2900–2905. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2900.
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Ten full-scale fully grouted reinforced concrete masonry shear walls were tested under force-displacement controlled reversed cyclic lateral loads simulating seismic effects. Relevant experimental phenomena and data indicated four walls failing in shear failure and the other six walls failing in flexure to evaluate seismic performance under compress, flexure and shear combined action. The paper mainly examinates lateral bearing-load capacity through two parameters: initial crack and ultimate strength under different failure modes. Through experimental analysis it can be concluded that the shear strength at the initial crack and ultimate load improved with the increased applied axial stress, and the increment of the shear strength was different in shear failure and flexural failure modes. Meanwhile, the ratio of the initial crack load to ultimate load on shear mechanism was from 0.57 to0.59,which was more stable than that(from 0.52 to 0.66)on flexural mechanism. In other words, the applied axial stress have more significant influence on flexural failure walls than shear ones.
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Sun, Li, Ajay P. Malshe, Wenping Jiang i Philip H. McCluskey. "Effects of CO2 Laser Surface Processing on Fracture Behavior of Silicon Nitride Ceramic". Journal of Engineering Materials and Technology 128, nr 3 (23.01.2006): 460–67. http://dx.doi.org/10.1115/1.2203104.
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Surface defects generated by grinding deteriorate the flexural strength of the silicon nitride (Si3N4) ceramic. In this paper, CO2 laser surface processing was applied to eliminate the grinding-induced defects. SEM micrograph showed that the surface integrity of Si3N4 samples was improved after laser processing. Four-point bending tests and fractographic analysis indicated that the flexural strength and fracture origins were affected by the change of surface integrity in laser-treated Si3N4 samples. The effect of grinding-induced residual stress on flexural strength of laser-treated samples was discussed. It was concluded that laser surface processing had significant effects on fracture behavior of flexure Si3N4 samples.
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Balos, Sebastian, Branislava Petronijevic Sarcev, Ivan Sarcev, Petar Janjatovic, Branka Pilic i Tatjana Balos. "Flexural Modulus and Strength of Cold Cured Poly(methylmethacrylate) Reinforced with TiO2 Nano Particles". Materiale Plastice 57, nr 4 (6.01.2021): 13–20. http://dx.doi.org/10.37358/mp.20.4.5402.
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The most significant disadvantage of cold cured poly (methyl methacrylate) - PMMA is its poor mechanical properties, mainly in flexure. The aim of this work is to explore the modulus and flexural strength of modified cold cured PMMA modified with low TiO2 addition, which can also have antibacterial properties. Commercial cold cured PMMA resin, consisting of powder and liquid components, were modified by adding 0.05 %, 0.2 %, and 1.5 wt. % 20 nm hydrophobic TiO2. The specimen s flexural modulus and strength were tested, while heat properties were determined with DSC analysis. SEM and EDX were used to study fracture surfaces of tested specimens. In all modified specimens, an increased flexural modulus and flexural strength were recorded. In all specimens, the appearance of agglomerates was noted. Glass transition temperatures also increased, as the result of the appearance of polymer chains with reduced mobility around nanoparticles. 0.2 % of 20 nm TiO2 nanoparticle content proved to be the most efficient in increasing flexural modulus and strength.
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Kadhem, Ali Abbas, Hayder Abbas Al-Yousefi i Qusay A. Jabal. "Effects of Using Corn Cover Fibers on Some Mechanical Properties of Concrete". Key Engineering Materials 895 (3.08.2021): 41–49. http://dx.doi.org/10.4028/www.scientific.net/kem.895.41.
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This investigation aims to use corn cover as natural fibers in concrete mixes to improve some mechanical properties like compressive strength, tensile strength, and flexural strength. using any type of fiber in concrete, in general, can improve the tensile and flexural strength of concrete. Concrete is weak in tension, so using fibers such as natural fibers like trunk fibers or industrial fibers such as steel fibers can improve tensile, the flexural strength of concrete and that may be decreasing the use of steel reinforcement in concrete, and also fibers can improve toughness and ductility of concrete because of its work inside the concrete that can reduce the propagation of cracks under loading. This study shows slight improvement on compressive strength by using fibers, but high increments in flexural strength, the optimum ratio of corn cover fibers was 2.5% by weight of cement which gives the highest values in compressive strength and flexural strength. compressive strength increased from (31.2 to 35.9) MPa (about 15% increment), increment for flexural strength was 70.6% for the optimum fibers content and the failure by using corn fibers was a ductile failure compared with plain concrete that gives sudden failure under flexure load, also tensile strength increased by using fibers, more fibers content beyond or more than 2.5% give lower values for the mechanical properties.
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Hong, Xinghua, Hui Wang i Feiting Shi. "Influence of NaCl Freeze Thaw Cycles and Cyclic Loading on the Mechanical Performance and Permeability of Sulphoaluminate Cement Reactive Powder Concrete". Coatings 10, nr 12 (16.12.2020): 1227. http://dx.doi.org/10.3390/coatings10121227.
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This paper aimed to investigate the coupling effects of NaCl freeze–thaw cycles and cyclic loading on the mechanical performance and permeability of sulphoaluminate cement reactive powder concrete (RPC). Firstly, the compressive and flexural strengths of sulphoaluminate cement RPC were investigated. Then, the chloride ion permeability, mechanical strengths (compressive and flexural strengths) and mass loss were determined. Results indicated that the increased steel fibers content and curing age played positive roles in the mechanical strengths. The threshold values of steel fibers and curing age were 3.0% and 14 days. Sulphoaluminate cement RPC with early curing age (5 h) showed relatively high mechanical strengths: flexural strength (8.69~17.51 MPa), and compressive strength (34.1~38.5 MPa). The mass loss, the chloride migration coefficient, and the compressive strength loss increased linearly with NaCl freeze–thaw cycles. Meanwhile, the flexural strength loss increased with the exponential function. The relative dynamic modulus of elasticity of specimens decreased linearly with the increased freeze–thaw cycles. Finally, it was observed from this paper, cyclic loading demonstrated negative roles on the mechanical strengths and resistance to chloride penetration.
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Ahmad, Shamsad. "Prediction of residual flexural strength of corroded reinforced concrete beams". Anti-Corrosion Methods and Materials 64, nr 1 (3.01.2017): 69–74. http://dx.doi.org/10.1108/acmm-11-2015-1599.
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Purpose This study aims to make an effort to develop a model to predict the residual flexural strength of reinforced concrete beams subjected to reinforcement corrosion. Design/methodology/approach For generating the required data to develop the model, a set of experimental variables was considered that included corrosion current density, corrosion duration, rebar diameter and thickness of concrete cover. A total of 28 sets of reinforced concrete beams of size 150 × 150 × 1,100 mm were cast, of which 4 sets of un-corroded beams were tested in four-point bend test as control beams and the remaining 24 sets of beams were subjected to accelerated rebar corrosion inducing different levels of corrosion current densities for different durations. Corroded beams were also tested in flexure, and test results of un-corroded and corroded beams were utilized to obtain an empirical model for estimating the residual flexural strength of beams for given corrosion current density, corrosion duration and diameter of the rebars. Findings Comparison of the residual flexural strengths measured experimentally for a set of corroded beams, reported in literature, with that predicted using the model proposed in this study indicates that the proposed model has a reasonably good accuracy. Originality/value The empirical model obtained under this work can be used as a simple tool to predict residual flexural strength of corroded beams using the input data that include rebar corrosion rate, corrosion duration after initiation and diameter of rebars.
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Khalil, Wasan, Hisham Ahmed i Zainab Hussein. "Behavior of high performance artificial lightweight aggregate concrete reinforced with hybrid fibers". MATEC Web of Conferences 162 (2018): 02001. http://dx.doi.org/10.1051/matecconf/201816202001.
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In this investigation, sustainable High Performance Lightweight Aggregate Concrete (HPLWAC) containing artificial aggregate as coarse lightweight aggregate (LWA) and reinforced with mono fiber, double and triple hybrid fibers in different types and aspect ratios were produced. High performance artificial lightweight aggregate concrete mix with compressive strength of 47 MPa, oven dry density of 1828 kg/m3 at 28 days was prepared. The Fibers used included, macro hooked steel fiber with aspect ratio of 60 (type S1), macro crimped plastic fiber (P) with aspect ratio of 63, micro steel fiber with aspect ratio of 65 (type S), and micro polypropylene fiber (PP) with aspect ratio of 667. Four HPLWAC mixes were prepared including, one plain concrete mix (without fiber), one mono fiber reinforced concrete mixes (reinforced with plastic fiber with 0.75% volume fraction), one double hybrid fiber reinforced concrete mixes (0.5% plastic fiber + 0.25% steel fiber type S), and a mix with triple hybrid fiber (0.25% steel fiber type S1+ 0.25% polypropylene fiber + 0.25% steel fiber type S). Fresh (workability and fresh density) and hardened concrete properties (oven dry density, compressive strength, ultrasonic pulse velocity, splitting tensile strength, flexural strength, static modules of elasticity, thermal conductively, and water absorption) were studied. Generally, mono and hybrid (double and triple) fiber reinforced HPLWAC specimens give a significant increase in splitting tensile strength and flexural strength compared with plain HPLWAC specimens. The percentage increases in splitting tensile strength for specimens with mono plastic fiber are, 20.8%, 31.9%, 36.4% and 41%, while the percentage increases in flexure strength are 19.5%, 37%, 33.9% and 34.2% at 7, 28, 60, 90 days age respectively relative to the plain concrete. The maximum splitting tensile and flexure strengths were recorded for triple hybrid fiber reinforced HPLWAC specimens. The percentage increases in splitting tensile strength for triple hybrid fiber reinforced specimens are 19.5%, 37%, 33.9% and 34.2%, while the percentage increases in flexure strength are 50.5%, 62.4. %, 66.8% and 62.2% at 7, 28, 60 and 90 days age respectively relative to the plain concrete specimens.
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Kakar, Akshay, Elammaran Jayamani, Muhammad Khusairy bin Bakri i Soon Kok Heng. "Heat Treated Luffa - PLA Composites: Effect of Cyclic Moisture Absorption and Desorption on the Mechanical Properties". Materials Science Forum 917 (marzec 2018): 42–46. http://dx.doi.org/10.4028/www.scientific.net/msf.917.42.
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The goal of this study was to investigate the influence of cyclic hot and cold water absorption and desorption on the flexural and impact strengths of luffa – PLA biocomposites. PLA was reinforced with heat treated luffa fibers with the fiber loadings: 5 vol.%, 10 vol.%, 15 vol.% and 20 vol.%. Based on the test results the biocomposite with the highest flexural and impact strengths was selected for water absorption and desorption cycles. The biocomposites were subjected to 56 cycles of hot and cold water absorption and desorption. The biocomposites were tested for their strengths after every 14 cycles. The absorption and desorption decreased the flexural and impact strengths, affecting the impact strength more than the flexural strength.
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Chen, Junhao, Han Li, Lijin Lian i Gen Lu. "Comparison of Mechanical Properties and Sensitivity of Compressive and Flexural Strength of Artificial Frozen Sand". Geofluids 2022 (10.11.2022): 1–8. http://dx.doi.org/10.1155/2022/7419030.
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Some zones of freezing curtains of subway contact channels are subjected to compression and tension. Thus, understanding the mechanical properties and relationship between the compressive and flexural strengths of frozen soil is crucial. In this regard, this study considered sandy soil from Fuzhou as an example to perform uniaxial compressive and three-point flexural strength tests under different moisture content and curing conditions. The results showed that the uniaxial compressive and three-point flexural strengths of frozen soil were directly correlated with the moisture content and inversely correlated with curing temperature. Moreover, the compressive strength was significantly higher than the flexural strength, and the ratio was between 1.68 and 3.41. The sensitivity analysis for two factors affecting the strength was performed using the grey correlation analysis method. The moisture content showed a stronger effect on the uniaxial compressive strength of frozen sand. In contrast, the curing temperature substantially affected the three-point flexural strength. This study provides a reference for optimizing the freezing scheme for subway connection channels.
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Shakir Muwashee, Rawa, Hamid Athab Al-Jameel i Qusay Abdulhameed Jabai. "Investigating the Behavior of Concrete and Mortar Reinforced with Aluminum Waste Strips". International Journal of Engineering & Technology 7, nr 4.37 (13.12.2018): 211. http://dx.doi.org/10.14419/ijet.v7i4.37.24103.
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Composite concrete such as fiber reinforced concrete is widely used in structures because of its excellent properties such as compressive, flexural and tensile strengths and also high modulus of elasticity because it gives lower strain values under loading and too fewer cracks propagation. In this study, Aluminum strips was prepared by cutting the Coca- Cola cans as strips in concrete. The reason of using Aluminum strip is low density and good tensile strength (about 310 MPa) and also has a good ductility. The results of this study show good improvements in compressive, tensile and flexural strengths using 117 tested specimens for both concrete and mortar. In brief, about 22 % increment in compressive strength of Aluminum strip concrete and flexural strength increases from 3.31 MPa to 11.20 MPa when using Aluminum strips with 2.5 % by volume of concrete. The reinforced mortar with Aluminum strips demonstrates significant increments which are 27% for compressive strength and more than 100% for both flexural and tensile strengths comparing with reference mix.
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Srivastava, V. K. "Influence of Particles on the Mechanical Properties of CFRP Composites". Engineering Plastics 4, nr 6 (styczeń 1996): 147823919600400. http://dx.doi.org/10.1177/147823919600400603.
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Cross-plied carbon fibre reinforced epoxy resin composites (CFRP) filled with graphite, silicon carbide and polyethylene particles in the range from 0.5 to 7% by volume of resin were prepared and their mechanical behaviour investigated by tensile, compression, flexure and Izod Impact tests. The results showed that the Izod Impact energy of the un-notched CFRP improved by the addition of all these kinds of particles and that the disc compression strength also increased by the addition of graphite and silicon carbide. However, polyethylene reduced the disc compression strength owing to the larger particle size compared to other fillers. The tensile and flexural strengths decreased as a result of the addition of all these types of particles.
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Srivastava, V. K. "Influence of Particles on the Mechanical Properties of CFRP Composites". Polymers and Polymer Composites 4, nr 6 (wrzesień 1996): 407–10. http://dx.doi.org/10.1177/096739119600400603.
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Cross-plied carbon fibre reinforced epoxy resin composites (CFRP) filled with graphite, silicon carbide and polyethylene particles in the range from 0.5 to 7% by volume of resin were prepared and their mechanical behaviour investigated by tensile, compression, flexure and Izod Impact tests. The results showed that the Izod Impact energy of the un-notched CFRP improved by the addition of all these kinds of particles and that the disc compression strength also increased by the addition of graphite and silicon carbide. However, polyethylene reduced the disc compression strength owing to the larger particle size compared to other fillers. The tensile and flexural strengths decreased as a result of the addition of all these types of particles.
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Hussein, Sary, i Azad Mohammed. "Mechanical properties of concrete reinforced with hybrid polypropylene- PET waste fibers". Sulaimani Journal for Engineering Sciences 8, nr 1 (1.08.2021): 10–22. http://dx.doi.org/10.17656/sjes.10144.
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In this article, flexural strength and compressive strength of concrete containing polypropylene fiber (PP), polyethylene terephthalate (PET) waste fiber and a combination between them were experimentally investigated. For this reason, laboratory experiments were performed on a total of 40 mixes. Results show that compressive strength property of concrete reinforced with PET waste fiber is not comparable to that of concrete reinforced with PP fiber, in which there is a compressive strength reduction, and the effect of PET fiber length on the strength is not important. Behavior of concrete contained PET waste fiber in flexure was found better. There is a good opportunity to use a hybrid fiber (25% PET and 75% PP) to enhance flexural strength of concrete.
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Saquib, Shahabe, AlQarni Abdullah, Das Gotam, Naqash Talib, Sibghatullah Muhammad i AlHaid Sultana. "Comparative Evaluation of Flexural Strength and Flexural Modulus of Different Periodontal Splint Materials: An In Vitro Study". Applied Sciences 9, nr 19 (8.10.2019): 4197. http://dx.doi.org/10.3390/app9194197.
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Splinting of the mobile teeth is a critical part of periodontal management to improve the prognosis and longevity of stable results of periodontally compromised teeth with increased mobility. Different types of splints are used in the dental field based on their mechanical and physical properties.The objective of the current in vitro study was to evaluate the flexure strength and flexural modulus of different types of splinting materials, such as: composite block, ligature wire, Ribbond®, InFibra®, and F-splint-Aid® bonded utilizing Flowable composites resin material. Seventy-five bar specimens were prepared with the dimensions of 25 × 4 × 2 mm, utilizing split metallic mold. Specimens were divided equally (n = 15) into five groups (one control group, four test groups). Different layers of splinting material were placed in between the layers of composite before curing. All the specimens were subjected to a three-point bending test by using a universal testing machine to calculate the flexural strength and flexural modulus. The entire data was subjected to statistical tests to evaluate the significance. Specimens from composite block groups showed the least mean value for flexural strength (89.15 ± 9.70 MPa) and flexural modulus (4.310 ± 0.912 GPa). Whereas, the highest mean value for flexural strength (168.04 ± 45.95 MPa) and flexural modulus (5.861 ± 0.501 GPa) were recorded by Ribbond® specimens. Inter group comparison of flexural strength showed statistically significant differences (P-value < 0.05), whereas comparison of flexural modulus showed non-significant difference among the groups (P-value > 0.05). Within the limitation of the present study, it was concluded that the Ribbond® exhibits maximum flexural strength and flexural modulus, whereas the composite blocks recorded the least values. Still, the decision making depends on the clinical scenario and the unique characteristic of each splint material.
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Tarrés, Oliver-Ortega, Espinach, Mutjé, Delgado-Aguilar i Méndez. "Determination of Mean Intrinsic Flexural Strength and Coupling Factor of Natural Fiber Reinforcement in Polylactic Acid Biocomposites". Polymers 11, nr 11 (23.10.2019): 1736. http://dx.doi.org/10.3390/polym11111736.
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This paper is focused on the flexural properties of bleached kraft softwood fibers, bio-based, biodegradable, and a globally available reinforcement commonly used in papermaking, of reinforced polylactic acid (PLA) composites. The matrix, polylactic acid, is also a bio-based and biodegradable polymer. Flexural properties of composites incorporating percentages of reinforcement ranging from 15 to 30 wt % were measured and discussed. Another objective was to evaluate the strength of the interface between the matrix and the reinforcements, using the rule of mixtures to determine the coupling factor. Nonetheless, this rule of mixtures presents two unknowns, the coupling factor and the intrinsic flexural strength of the reinforcement. Hence, applying a ratio between the tensile and flexural intrinsic strengths and a defined fiber tensile and flexural strength factors, derived from the rule of mixtures is proposed. The literature lacks a precise evaluation of the intrinsic tensile strength of the reinforcements. In order to obtain such intrinsic tensile strength, we used the Kelly and Tyson modified equation as well as the solution provided by Bowyer and Bader. Finally, we were able to characterize the intrinsic flexural strengths of the fibers when used as reinforcement of polylactic acid.
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Wilson, H. S. "Performance of ilmenite concrete at sustained elevated temperatures". Canadian Journal of Civil Engineering 15, nr 5 (1.10.1988): 776–83. http://dx.doi.org/10.1139/l88-102.
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Two similar mixes were made with cement contents of about 350 kg/m3 and a water–cement ratio of 0.50. The concrete specimens, moist cured for 7 days, were cured in air for 28 and 120 days, respectively, prior to heating. The exposure temperatures were 75, 150, 300, and 450 °C. The periods of exposure at each temperature were 2, 30, and 120 days.The compressive strengths, before heating, of the specimens cured for 35 and 120 days were 41.0 and 46.2 MPa, respectively, and the flexural strengths were 4.9 and 5.8 MPa. Compared with those strengths, the strengths of the specimens heated for 30 days or more increased at 75 °C but decreased at higher temperatures. The losses increased with increase in temperature, reaching about 30% at 450 °C.The flexural strength of the concrete cured in air for 28 days was more adversely affected than was the compressive strength. The flexural and compressive strengths of the concrete cured in air for 120 days were affected to about the same degree. The longer curing period had little effect on the relative losses in compressive strength, but the longer curing period reduced the loss in flexural strength. In most applications, the loss in strength could be compensated by proportioning the mix to overdesign for strength. Key words: high-density concrete, ilmenite, aggregates, high temperature, mechanical properties, nondestructive tests.
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Timco, G. W. "Flexural Strength and Fracture Toughness of Urea Model Ice". Journal of Energy Resources Technology 107, nr 4 (1.12.1985): 498–505. http://dx.doi.org/10.1115/1.3231225.
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In many tests of ice-structure interactions performed using physical modeling techniques, the ice can fail in bending, flexure or by tensile cracking. Because of this, it is necessary to know and understand the flexural and fracture toughness properties of the model ice used in the test in order to be able to better interpret the results. In spite of this, to date there has been only a limited number of tests to measure the flexural behavior and the parameters influencing the flexural response of the model ice. The fracture toughness of model ice has not been measured. In this paper, the flexural behavior and fracture toughness of both freshwater ice and sea ice are reviewed in order to establish the prototype values and behavior which must be scaled for the model test. The results of a series of tests on the flexural properties of the model ice are presented and discussed in terms of the parameters which influence the strength including warmup time and temperature, test type (cantilever or simple beam), loading rate and loading direction. The fracture toughness of the model ice has been measured and the results are presented and compared to the prototype values for freshwater ice and sea ice. A comparison is made to assess the accuracy of the scalability of these properties of the ice.
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Jaradat, Omar A., David I. McLean i M. Lee Marsh. "Strength Degradation of Existing Bridge Columns under Seismic Loading". Transportation Research Record: Journal of the Transportation Research Board 1541, nr 1 (styczeń 1996): 29–42. http://dx.doi.org/10.1177/0361198196154100105.
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The strength and degradation behavior of reinforced concrete bridge columns under seismic loading were investigated. Experimental tests were conducted on four reduced-scale column specimens that incorporated deficiencies selected to be representative of those present in existing bridges designed before 1971. The columns were fixed against rotation at both the top and bottom, resulting in a transfer of shear forces through the column even after the lower hinging region lost its flexural capacity. The specimens were subjected to increasing levels of cycled inelastic displacements under constant axial load. The focus of the study was to characterize the load and displacement capacities present in older columns for purposes of seismic assessment and retrofit design. Flexure-dominated failures occurred in three of the specimens. A rapid degradation in flexural strength was observed at the bottom hinging regions of the tested columns because of the presence of lap splices and poor confinement. Top hinging regions that did not have lap splices exhibited degradation in flexural capacities at higher displacement ductilities because of eventual longitudinal bar buckling. In the fourth specimen, flexural yielding was initially observed at both the top and bottom of the column, but this was followed by an eventual brittle shear failure. Various procedures for assessing flexural and shear behaviors were compared with the observed experimental results.
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Smarzewski, Piotr. "Comparative Fracture Properties of Four Fibre Reinforced High Performance Cementitious Composites". Materials 13, nr 11 (8.06.2020): 2612. http://dx.doi.org/10.3390/ma13112612.
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This study investigates the fracture properties of high performance cementitious composites (HPCC) with four different types of fibres and with volume fraction content 3%. The four fibres are steel hooked end (S), polypropylene crimped (PP), basalt chopped (B), and glass (G) fibres. The tests were carried out in accordance with the RILEM recommendations. In order to examine the fresh properties of HPCC the slump flow tests were performed. Twelve fibre reinforced HPCC beam specimens with notch were cast and tested using central point loading experiments. In addition, experimental tests of the compressive strength and splitting tensile strength were carried out. The test results made it possible to obtain representative fracture parameters, such as the equivalent strengths, residual strengths, and fracture energy of fibre reinforced HPCC. The S fibre specimens showed the best performance in terms of workability, compressive strength, tensile splitting strength, and fracture energy at large deflection. On the other hand, G fibre specimens exhibited the best performance in terms of flexural strength, equivalent flexural strength at higher deflection, and residual flexural strength at lower deflection. In terms of equivalent flexural strength at lower deflection and residual flexural strength at higher deflection, basalt fibre specimens performed the best. On the contrary, polypropylene fibre reinforced beam specimens revealed the highest deflection capacity.
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Ahn. "Ultimate Flexural Strength of Cylindrical Steel Shell for Wind Tower". Journal of Korean Society of Steel Construction 27, nr 1 (2015): 087. http://dx.doi.org/10.7781/kjoss.2015.27.1.087.
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Ahn. "Ultimate Flexural Strength of Cylindrical Steel Shell for Wind Tower". Journal of Korean Society of Steel Construction 27, nr 1 (2015): 109. http://dx.doi.org/10.7781/kjoss.2015.27.1.109.
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Yoshida, H., T. Ogasa i M. Uemura. "Local Stress Distribution in the Vicinity of Loading Points in Flexural Test of Orthotropic Beams". Journal of Energy Resources Technology 113, nr 4 (1.12.1991): 230–34. http://dx.doi.org/10.1115/1.2905905.
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The two-dimensional stress distributions in orthotopic composite beam under 4-point flexure are analyzed by replacing the concentrated load by distributing pressure in the vicinity of loading nose and by expanding the stress function for compatability equation in terms of Fourier series. The validity of analytical results is verified experimentally by using the photoelastic film-coating technique on unidirectional reinforced plastics. It is shown that the local stress distributions around the loading points are complicated and are very different from those predicted by elementary beam theory; and hence, the reliability of flexural strength and interlaminar shear strength defined by elementary beam theory are in question. It is suggested that the 4-point flexure is reasonable and recommendable as a standard testing method compared with the 3-point flexural one.
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Yeo, J. S., S. Koting, C. C. Onn i K. H. Mo. "Optimisation of mix design of concrete paving block using response surface methodology". Journal of Physics: Conference Series 2521, nr 1 (1.06.2023): 012012. http://dx.doi.org/10.1088/1742-6596/2521/1/012012.
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Abstract This study investigated the optimal water/binder (w/b) and aggregate/binder (a/b) ratios in producing a concrete paving block. The w/b and a/b ratios in the concrete paving block were optimised using the response surface methodology (RSM), considering the performances of the ultrasonic pulse velocity (UPV), flexural, and compressive strengths. Regression modelling was conducted to represent the relationships between the UPV and compressive strength and the compressive and flexural strengths. Generally, the UPV, flexural, and compressive strengths increased with the increment of w/b ratio and reduction of a/b ratio. The RSM suggested optimal ratios of 0.35 for w/b and 3.50 for a/b, that the paving block could exhibit UPV, flexural, and compressive strengths of 4.11 km/s, 4.13 MPa, and 33.2 MPa, respectively. The predicted values from the RSM varied less than 6% compared to the experimental values. The polynomial regression model could effectively represent the relationship between the UPV and the compressive strength and the relationship between the compressive and flexural strengths of the concrete paving block.
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He, Xi Xi, i Ping Fang. "Influence of Concrete Strength Grade and Age on Three Tensile Strengths". Advanced Materials Research 450-451 (styczeń 2012): 179–86. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.179.
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Uniaxial tensile strength is one of the important strength parameters of concrete. In this study, two test methods were applied to determine direct tensile strength, splitting tensile strength and flexural strength of fly ash concrete specimens with the same cross section and different strength grades. Relationship among the uniaxial tensile, splitting tensile and flexural strength of concrete were researched. Furthermore, the influence of concrete strength and age to the three tensile strengths were specifically analyzed in the paper.
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Bansal, Manik, Indra Vir Singh, Bhanu K. Mishra, Kamal Sharma i IA Khan. "A numerical prediction of flexural strength probability for NBG-18 nuclear grade graphite using strength pair model". Journal of Strain Analysis for Engineering Design 52, nr 3 (17.03.2017): 204–11. http://dx.doi.org/10.1177/0309324717698609.
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In this work, a strength pair model has been proposed for the numerical prediction of flexural strength probability of NBG-18 nuclear grade graphite. The input to the proposed model is a random strength pair of tensile and compressive strengths whose value is based on its probability of occurrence in the experimental data. A finite element–based deterministic numerical approach has been implemented. To account for the large difference in tensile and compressive strengths, Drucker–Prager failure criteria has been implemented. The failure envelope of the Drucker–Prager failure criteria is assumed to have uniaxial fit with Mohr–Coulomb model in the principal stress space. A total of 292 simulations with random pairs of tensile and compressive strength are performed on a three-point bend specimen to obtain a set of flexural strength data. The flexural strength data obtained through numerical simulations are fitted using normal and Weibull distributions. The flexural strength probability obtained from the proposed model is found on conservative side. A goodness-of-fit test concludes that Weibull distribution fits the numerical data better than normal distribution.
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Mohammadi, Hossein, Seyedmohammad Mirmehdi i Lisiane Nunes Hugen. "RICE STRAW/THERMOPLASTIC COMPOSITE: EFFECT OF FILLER LOADING, POLYMER TYPE AND MOISTURE ABSORPTION ON THE PERFORMANCE". CERNE 22, nr 4 (grudzień 2016): 449–56. http://dx.doi.org/10.1590/01047760201622042192.
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ABSTRAT Thermoplastic composites made with 45, 60 and 75% of rice straw as filler and two types of thermoplastics, virgin polyethylene (PE) and polypropylene (PP) were evaluated. The final boards were made with and without maleic anhydride modified polypropylene (MAPP) at 2% of the total weight of each specimen. The flexural and tensile strengths were measured for dry composites and also measured after 24 h of water immersion of the composites (wet condition). By increasing the filler content, the flexural and tensile strengths and also the density of the specimens decreased. The type of matrix (PE or PP) did not affect significantly the flexural strength, but PP led to higher values of tensile strength for low fiber loadings (45% and 60%). Coupling agents increased the flexural and tensile strength. After water immersion, modulus of elasticity and modulus of rupture were decreased, while tensile strength was less influenced.
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Amer, Asmaa, Cherif Mohsen i Raiessa Hashem. "Effect of Nanosilica Incorporation on Flexural Strength, Shear Bond Strength, and Color of Veneering Porcelain after Thermocycling". Open Access Macedonian Journal of Medical Sciences 10, nr D (1.09.2022): 380–88. http://dx.doi.org/10.3889/oamjms.2022.10390.
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AIM: The focus of this research was to see how silica nanoparticles changed veneering porcelain over a zirconia core affected flexure strength, shear bond strength, and color. METHODS: A total number of 30 zirconia core veneer samples were constructed and classified according to silica nanoparticles modification of veneering porcelain into two groups: Group 1 (control group) veneering porcelain without any modification (n = 15) and Group 2 (modified group) veneering porcelain modified by silica nanoparticles (n = 15). Silica nanoparticles were added to the veneering porcelain powder at a rate of 5% by weight. Silica nanoparticles powder and veneering porcelain powder were manually crushed for about 10 min using a pestle and mortar then the mixed powder was combined with the porcelain moldings liquid to make a paste. After thermal cycling, each group was examined for flexural strength, shear bond strength, and color measurement (n = 5). Universal testing equipment was used to determine flexural and shear bond strength. The color shift was measured using a spectrophotometer. RESULTS: Flexural strength levels in the modified group (280.9 ± 29.85 Mpa) were substantially higher than in the control group (431.78 ± 22.73 Mpa). Shear bond strength values in the modified group (34.31 ± 5.6) were significantly higher than in the control group (26.97 ± 4.03). Color change was within the clinical acceptable range (1.71 ± 0.32). CONCLUSIONS: The addition of silica nanoparticles to veneering porcelain improved the flexural and shear bond strength, as well as, color change was within the clinical acceptable limits.
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Cui, Jun, Yi Fan Chen, Yong Lie Chao, Chun Xia Chen, Jun Ou, Lei Sui i Wei Qun Zhang. "Bi-Axial Flexure Strength, Weibull Modulus and Fracture Mode of Alumina Glass-Infiltrated Core/Veneer Ceramic Composites". Key Engineering Materials 353-358 (wrzesień 2007): 1556–59. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1556.
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The purpose of this study is to determine the bi-axial flexural strength, weibull modulus and fracture mode of bilayered alumina glass-infiltrated core and the veneering porcelain. Forty disk specimens were fabricated from alumina glass-infiltrated core (HSDC-A) and veneer porcelain (Vintage AL). The specimens were equally divided into four groups as: MV, monolithic specimens of veneer material; MC, monolithic specimens of core material; BV, bilayered specimens with the veneer in tension; BC, bilayered specimens with core material in tension. Mean flexure strength, standard deviation and associated Weibull modulus were determined using bi-axial flexure (ball-on-ring) for each group. Both optical and scanning electron microscopy were employed for identification of the fracture mode and origin. The surface loaded in tension influenced the bi-axial flexural strength and reliability of the composites. The frequency of specimen delamination, Hertzian cone formation and sub-critical radial cracking in the bilayered discs are also dependent on the surface loaded in tension.