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1
Hollý, Ivan. "Experimental Investigation of Bond between GFRP Reinforcement and Concrete". Solid State Phenomena 309 (sierpień 2020): 140–45. http://dx.doi.org/10.4028/www.scientific.net/ssp.309.140.
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The reinforcing steel embedded in concrete is generally protected against corrosion by the high alkalinity (pH = 12.5 to 13.5) of the concrete pore solution. The structural degradation of concrete structures due to reinforcement’s corrosion has an impact on the safety, serviceability and durability of the structure. The corrosion of reinforcements in the construction of a transport infrastructure (especially bridges), parking areas, etc., is primarily initiated by chlorides from de-icing salts. Glass fiber reinforcement polymer (GFRP) bars are suitable alternatives to steel bars in reinforced concrete applications. The bond between concrete and reinforcement is one of the basic requirements for the composite action of both materials. The transfer of forces between the steel reinforcement and the concrete is provided by the following mechanisms: adhesion, friction and mechanical interlocking. The bond between GFRP reinforcement and concrete is different and it is ensured by friction and mechanical interlocking of the rebar surface. The chemical bond does not originate between GFRP reinforcement and the surrounding concrete, so adhesion does not contribute to transfer of the bond forces. Some few test methods are used to determine the bond between GFRP reinforcement and concrete. The pull-out tests were used to determine the bond behavior between GFRP rebars and concrete. This paper describes the preparation, process, results and evaluation of the pull-out tests.
2
Hollý, Ivan, i Juraj Bilčík. "Effect of Chloride-Induced Steel Corrosion on Working Life of Concrete Structures". Solid State Phenomena 272 (luty 2018): 226–31. http://dx.doi.org/10.4028/www.scientific.net/ssp.272.226.
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The reinforcing steel embedded in concrete is generally protected against corrosion by the high alkalinity (pH = 12.5 to 13.5) of the concrete pore solution. The structural degradation of concrete structures due to reinforcement’s corrosion has an impact on the safety, serviceability and durability of the structure. The corrosion of reinforcements in the construction of a transport infrastructure (especially bridges), parking areas, etc., is primarily initiated by chlorides from de-icing salts. When corrosion is initiated, active corrosion results in a volumetric expansion of the corrosion products around the reinforcing bars against the surrounding concrete. Reinforcement corrosion causes a volume increase due to the oxidation of metallic iron, which is mainly responsible for exerting the expansive radial pressure at the steel–concrete interface and development of hoop tensile stresses in the surrounding concrete. When this tensile stress exceeds the tensile strength of the concrete, cracks are generated. Higher corrosion rates can lead to the cracking and spalling of the concrete cover. Continued corrosion of reinforcement causes a reduction of total loss of bond between concrete and reinforcement.
3
Kliukas, Romualdas, Ona Lukoševičienė, Arūnas Jaras i Bronius Jonaitis. "The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures". Applied Sciences 10, nr 10 (21.05.2020): 3570. http://dx.doi.org/10.3390/app10103570.
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This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.
4
Vlach, Tomáš, Magdaléna Novotná, Ctislav Fiala, Lenka Laiblová i Petr Hájek. "Cohesion of Composite Reinforcement Produced from Rovings with High Performance Concrete". Applied Mechanics and Materials 732 (luty 2015): 397–402. http://dx.doi.org/10.4028/www.scientific.net/amm.732.397.
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The reinforcement of concrete with composite technical textile creates a tensile load-bearing capacity. It allows the elimination of steel reinforcement and minimisation of concrete cover. Based on this, the concrete cover is designed with respect to the cohesion of reinforcement with concrete. By using of textile reinforcement very thin structures could be created. The aim of this paper was to determine the interaction conditions of carbon and basalt composite reinforcement in a matrix of epoxy resin with high performance concrete (HPC). The tensile strength of used composite reinforcement and the other mechanical parameters of HPC were determined by experimental tests. Experiments copied the production method of technical textiles. These two combinations of materials present the influence on the design of the structures with textile reinforcements.
5
Zhang, Shuang, Hai Jun Wu, Zheng Jun Tan i Feng Lei Huang. "Theoretical Analysis of Dynamic Spherical Cavity Expansion in Reinforced Concretes". Key Engineering Materials 715 (wrzesień 2016): 222–27. http://dx.doi.org/10.4028/www.scientific.net/kem.715.222.
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This paper aims to establish a model that considers the penetration resistance caused by the constraint effects of steel reinforcements on concrete. Firstly, based on the experiment phenomena that reinforcements increase the toughness and tensile strength of concretes, the fitting relational expression between toughness of reinforced concrete and ratio of reinforcement was used to improve the Griffith yield criterion for reinforced concrete. Then, the dynamic spherical cavity expansion analysis was developed using the improved Griffith yield criterion as constitutive model and the dilation equation as equation of state, and the response regions were consisted of six distinct zones: cavity, compaction zone, dilation zone, radially cracked zone, elastic zone and undisturbed zone. This dynamic analysis considered the compression and dilation of concretes at the same time and was applicable to the penetration problem of reinforced concrete target. At last, based on the theoretical model of this paper, the experiments of projectiles with different weights penetrating into reinforced concrete targets with different reinforcement ratios were calculated using penetration analysis method of rigid projectiles. The comparison results showed that the theoretical analysis model of this paper can be used to predict the depth of penetration and other physical parameters such as velocity and deceleration with certain rationality.
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Bilčík, Juraj, i Ivan Hollý. "Experimental Analysis of Reinforcement Corrosion on Bond Behaviour". Advanced Materials Research 1106 (czerwiec 2015): 140–43. http://dx.doi.org/10.4028/www.scientific.net/amr.1106.140.
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The corrosion of reinforcement is the major cause of damage of reinforced concrete structures. This has an impact on safety, serviceability and durability of the structure. The corrosion of steel in concrete reduces the cross sectional area of the reinforcement and decreases the bond between reinforcement and concrete. Corrosion products have a higher volume than steel, which produces internal stresses that lead to the cracking and spalling of the concrete cover. The paper analyses the effect of the chloride-initiated corrosion of reinforcements on bond behaviour.
7
Rezaei, Mehdi, Siti Aminah Osman i Nandivaram E. Shanmugam. "PRIMARY AND SECONDARY REINFORCEMENTS IN REINFORCED CONCRETE CORBELS". Journal of Civil Engineering and Management 19, nr 6 (24.10.2013): 836–45. http://dx.doi.org/10.3846/13923730.2013.801896.
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The study is concerned with normal-strength concrete corbels. 30 such corbels were studied by finite element modelling and the variables considered include ratios of primary and secondary reinforcement, type of applied loading, vertical or horizontal. Finite element modelling with a software package LUSAS was used to analyse four series of corbels namely PV series (primary reinforcement with vertical loading), SV series (secondary reinforcement with vertical loading), PH series (primary reinforcement with horizontal loading) and SH series (secondary reinforcement with horizontal loading). The results indicate that corbels with neither primary reinforcement nor secondary reinforcement fail suddenly. In the case of PV series and SV series, corbels increase in ratio of primary and secondary reinforcement generally resulted in enhancement of strength and ductility when subjected to only vertical loading. This increase is significant up to 0.4% in the case of primary reinforcement and 0.3% in the case of secondary reinforcements. No noticeable change in ultimate load or ductility was observed for corbels in PH series and SH series.
8
Zhou, Jun Long, Zhong Wen Ou, Qiao Chen i Yun Chen. "The Influence of Admixtures on the Corrosion Protection Afforded Steel Reinforcement in Seawater-and-Seasand Concrete". Advanced Materials Research 250-253 (maj 2011): 81–89. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.81.
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It is inevitable for steel reinforcement to be corroded when mixed with seawater-and-seasand concrete. In order to improve steel corrosion protection properties of seawater-and-seasand concrete, reduce the chloride ion’s attack on steel reinforcement in structural concrete and lengthen the steel reinforcement’s service time, this paper presents an experimental study on whether admixtures like fly ash, slag and metakaolin in the seawater-and-seasand could retard the corrosion to steel reinforcement and provide protection to steel reinforcement in seawater-and-seasand concrete. The results indicated that metakaolin had a significant anti-corrosion effect and greatly enhanced the steel corrosion protection properties of seawater-and-seasand concrete whereas both fly ash and slag did not appear to have any obvious influence on curbing the corrosion of steel reinforcement.
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Kim, Joung Rae, Hyo-Gyoung Kwak, Byung-Suk Kim, Yangsu Kwon i El Mahdi Bouhjiti. "Finite element analyses and design of post-tensioned anchorage zone in ultra-high-performance concrete beams". Advances in Structural Engineering 22, nr 2 (20.07.2018): 323–36. http://dx.doi.org/10.1177/1369433218787727.
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This article presents analyses and the design of a post-tensioned anchorage zone made of ultra-high-performance concretes with three-dimensional finite element analyses. The structural behavior was investigated through the failure modes and cracking patterns to show the anchorage zone resistance enhancement with an increase of the strength in concrete. Since the anchorage failure is usually initiated from the local zone in the case of ultra-high-performance concrete beams that have compressive strength of more than 80 MPa, the placement of reinforcements can effectively be used to enhance the strength and ductility for the local zone. However, ultra-high-performance concrete requires a smaller amount of reinforcement than normal-strength concrete. Parametric analyses are carried out to show the effect of the spiral reinforcement on the strength of the anchorage zone, and comparison with the design guidelines in NCHRP Report 356 is made. Finally, improved guidelines are suggested to cover the design of ultra-high-performance concrete.
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Křížová, Klára, i Petr Novosad. "Verification of Rheological Properties of Self-Compacting Concrete with Reinforcement". Solid State Phenomena 249 (kwiecień 2016): 41–45. http://dx.doi.org/10.4028/www.scientific.net/ssp.249.41.
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The paper presents results of mechanical and physical tests of self-compacting concrete with fibre reinforcement. Self-compacting concretes belong to special types of concretes with filling ability without invoking external dynamic forces. Especially high storage rate and concrete access even in densely stored reinforcement, high homogenisation, low water-cement ratio and exclusion of external vibrations are benefits of SCC concretes. The highest risks that must be considered when designing this type of the concretes are their resistance to segregation, sedimentation, blocking and bleeding. Several SCC formulas with two types of fibres (steel, polypropylene) were designed and compared and the effects of fibres reinforcement on concrete selected properties were monitored in fresh and hardened condition, too.
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Olanitori, Lekan Makanju, i Jeremiah Ibukun Okusami. "Effect of Shear Reinforcement on Flexural Strengths of Normal Weight and Palm-Kernel Shell Reinforced Concrete Beams". European Journal of Sustainable Development 8, nr 2 (1.06.2019): 279. http://dx.doi.org/10.14207/ejsd.2019.v8n2p279.
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The focus of this research is to investigate the effect of shear reinforcement on flexural capacities of reinforced Normal Weight Concrete (NWC) and Palm Kernel Shell Concrete (PKSC) beams. Ten beams were cast: five from PKSC and five from NWC. The beams were with shear reinforcement spacing of 50 mm, 100 mm, 150 mm, 200 mm and without shear reinforcement respectively. The beams were loaded with a point load at beam centre, and the results showed that the flexural capacity of the beams decreases as the spacing of the shear reinforcements increases. The ultimate loads of PKSC beams were lesser than that of NWC beams by 9.0%, 7.1%, 14.5%, 21 and 26.8% for shear reinforcement spacing of 50 mm, 100 mm, 150 mm, 200 mm and for beam without shear reinforcements respectively. The deflections of the PKSC beams were greater than that of the NWC, hence the PKSC beams had more plastic rotation capacity than the NWC beams. The study shows that reinforced concrete beams produced from 20% partial replacement of crushed aggregate by PKS have the potential of being used for structural purposes in low cost buildings. Keywords: Palm Kernel Shell Concrete, Normal weight concrete, Palm kernel shell, Deflection, Shear reinforcement.
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Zhang, Jianwei, Wenbin Zheng, Cheng Yu i Wanlin Cao. "Shaking table test of reinforced concrete coupled shear walls with single layer of web reinforcement and inclined steel bars". Advances in Structural Engineering 21, nr 15 (19.05.2018): 2282–98. http://dx.doi.org/10.1177/1369433218772350.
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In this study, five 1/4 scaled shaking table tests were conducted to investigate the seismic performance of reinforced concrete coupled shear walls with single layer of web reinforcement and inclined steel bars. The five tested coupled shear walls included three models with normal opening ratio (19%) and two models with large hole ratio (27%). The three models with normal opening included one model with single layer of web reinforcement, two models with single layer of web reinforcement and 75° inclined steel bars in the limbs’ web or at the bottom. Two reinforced concrete coupled shear walls with large hole and single row of reinforcements also were tested with inclined reinforcements or without them. The dynamic characteristics, dynamic response, and failure mode of each model were compared and analyzed. The test and analysis results demonstrate that the inclined steel bars are identified as an efficient means of limiting overall deformation, increasing energy dissipation, and reducing the possible damage by earthquake for reinforced concrete coupled shear walls with single layer of web reinforcement. Thus, reinforced concrete coupled shear walls with inclined steel bars have better seismic performance than reinforced concrete coupled shear walls without inclined steel bars. With appropriate design, reinforced concrete coupled shear walls with single layer of web reinforcement and inclined steel bars can be applied in multi-story buildings.
13
Mao, Jize, Daoguang Jia, Zailin Yang i Nailiang Xiang. "Seismic Performance of Concrete Bridge Piers Reinforced with Hybrid Shape Memory Alloy (SMA) and Steel Bars". Journal of Earthquake and Tsunami 14, nr 01 (7.08.2019): 2050001. http://dx.doi.org/10.1142/s1793431120500013.
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Lack of corrosion resistance and post-earthquake resilience will inevitably result in a considerable loss of function for concrete bridge piers with conventional steel reinforcement. As an alternative to steel reinforcement, shape memory alloy (SMA)-based reinforcing bars are emerging for improving the seismic performance of concrete bridge piers. This paper presents an assessment of concrete bridge piers with different reinforcement alternatives, namely steel reinforcement, steel-SMA hybrid reinforcement and SMA reinforcement. The bridge piers with different reinforcements are designed having a same lateral resistance, or in other words, the flexural capacities of plastic hinges are designed equal. Based on this, numerical studies are conducted to investigate the relative performance of different bridge piers under seismic loadings. Seismic responses in terms of the maximum drift, residual drift as well as dissipated energy are obtained and compared. The results show that all the three cases with different reinforcements exhibit similar maximum drifts for different earthquake magnitudes. The SMA-reinforced bridge pier has the smallest post-earthquake residual displacement and dissipated energy, whereas the steel-reinforced pier shows the opposite responses. The steel-SMA hybrid reinforcement can achieve a reasonable balance between the residual deformation and energy dissipation.
14
Zhang, Guo Jun, Yong Bin Jia i Xi Lin Lu. "The Strain Change Rules of Full-Scale High Strength Concrete Frame Columns with High Axial Compression Rations". Advanced Materials Research 919-921 (kwiecień 2014): 288–91. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.288.
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Based on experimental study of 9 full-scale high-strength concrete(HSC) rectangular frame columns with high axial compression ratios, high-strength longitudinal reinforcements and transverse reinforcements and rectangular interlocking ties, their strain change rules of longitudinal reinforcement, stirrups and concrete were discussed and analyzed. The main results indicate as follows. The maximum tensile strain of longitudinal reinforcement decrease and the tensile strain of concrete increase quickly as the axial compression ratios and the strength grades of concrete are higher; the strains of outer stirrups are all the time greater than those of inner stirrups; the single brace stirrups have the same action with the closed stirrups.
15
Lukashevich, Viktor, Igor Efanov, Viktor Vlasov i Olga Lukashevich. "Asphalt concrete pavement reinforced with chemical fibers". MATEC Web of Conferences 216 (2018): 01013. http://dx.doi.org/10.1051/matecconf/201821601013.
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Asphalt concrete pavement which is currently built in accordance with the existing requirements does not withstand the standard service life. Various kinds of damages occur. Fiber reinforcement of asphalt concretes is one of the effective means to deal with deformations and fractures of road pavements, such as rutting, buckling, crack formation and shear. Chemical fibers serving as reinforcement are of great concern herein. The major purpose of this work was evaluation of reinforcement fibers resistance to natural environment and climatic impacts within the conditions of experimental production construction and studying compactibility of asphalt concrete mixture with fiber reinforcement. Infrared spectroscopy and physical-chemical investigations of fibers were used to study changing properties of fiber-forming polymer. Compactibility of asphalt concrete mixture with fiber reinforcement was determined upon compaction factor. Research results revealed insignificant influence of natural environment and climatic impacts on the properties of fiber reinforcement material. In order to obtain the standard compaction factor of asphalt concrete additional compacting impact is not required.
16
Lei, Min, Zihao Wang, Penghui Li, Liyi Zeng, Hongyao Liu, Zhidong Zhang i Huicheng Su. "Experimental Investigation on Short Concrete Columns Reinforced by Bamboo Scrimber under Axial Compression Loads". Advances in Civil Engineering 2020 (29.09.2020): 1–12. http://dx.doi.org/10.1155/2020/8886384.
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The paper presents bamboo scrimber bars as a reinforcing material instead of steel reinforcement in low-strength concrete columns. Twelve short concrete columns with different reinforcements are tested under axial compression load to study the axial compressive behavior of short concrete columns reinforced by bamboo scrimber. Three columns are reinforced concrete columns, and the other nine columns are bamboo scrimber reinforced concrete columns. The failure process, bearing capacity, axial deformation, and strain of the specimens are compared and analyzed. The results show that the bonding performance between the bamboo scrimber bars by surface treatment and low-strength concrete is excellent. In low-strength concrete columns, the material properties of bamboo bars play more thoroughly than those of steel bars. When the bamboo reinforcement ratio is increased, the concrete column ductility is significantly improved, but the bearing capacity of the concrete column is not increased. The bamboo scrimber bars with the size of 10 mm × 10 mm or 15 mm × 15 mm can be used as longitudinal bars of low-strength concrete columns. The ductility of the short concrete column with 2.56% bamboo scrimber reinforcement is close to that of the short concrete column with 0.72% steel reinforcement.
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Kadlec, Jaroslav, Ivailo Terzijski, František Girgle i Lukáš Zvolánek. "Effect of Lightweight Concrete Density on Bond Strength". Advanced Materials Research 1106 (czerwiec 2015): 33–36. http://dx.doi.org/10.4028/www.scientific.net/amr.1106.33.
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The main objective of this paper is connected with the search of an optimal anchorage length of reinforcement in lightweight and ultra-lightweight concretes. Experimentally obtained values of the bond stress between lightweight concrete and reinforcing bars are presented. The density classes of lightweight concrete were D1,0, D1,2 and D1,4. The results are compared with equal ones of normal density concrete. The tests with ordinary reinforcement and with non-metallic hybrid reinforcement C-GFPR (30% portion of carbon fibres) were conducted.
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Wang, Hui Li, Hong Wang i Si Feng Qin. "The Characteristic of Prestressed Concrete Pier Seismic Crack". Applied Mechanics and Materials 501-504 (styczeń 2014): 1628–32. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1628.
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Through three dimensional finite element analyzes, overall cast-in-place prestressed concrete pier seismic crack characteristic is researched. The separation formula finite element model is established by means of bilinear reinforce model and Kent-R.Park concretes model, without considering slip between concretes and. reinforce. It compares and analyzes the seismic crack characteristic between prestressed concrete pier and reinforcement concretes pier. The results show that the prestressed reinforcement can reduce the tensile zone of concrete, put off the appearance of cracks, improved the stiffness of pier, and reduced the top displacement.
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Bldr. Marafa Muhammad and Bldr. Tukur Almustafa, Bldr Nagande Umar. "Effects of Corrosion to the Performance of Steel Reinforcement Embedded in Concrete under Different Aggressive Environments". International Journal for Modern Trends in Science and Technology 06, nr 09 (25.11.2020): 139–43. http://dx.doi.org/10.46501/ijmtst060921.
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The corrosion of reinforcement steel bars in concrete has been established as the major factor causing widespread degradation of concrete structures. Corrosion of reinforcement in concrete leads to reduction of good bonding between steel and concrete, decrease of steel cross-sectional area, cracking and loss of serviceability. This paper investigates the behavior and Performance of reinforcement bar embedded in concrete structure under a variety of aggressive environments. The study used 16 mm diameter reinforcement bars embedded in concrete with a uniform cover of 50 mm in 200 mm x 200 mm x 750 mm concrete beam, the curing period of concrete is 28 days. After completion of 28 days’ moisture curing period, the beam was loaded in flexure causing cracking of the concrete, thereby exposing the steel reinforcements. The cracked reinforced concrete beams were then immersed in different aggressive solutions of H2So4 (Sulfuric Acid), HCl (hydrochloric acid), HNO3 (hydrogen trioxonitrate), NaOH (sodium hydroxide) and NaCl (Sodium Chloride) for a duration of six months. At the end of this curing period, the embedded steel reinforcement was removed and cleaned off the attached concrete, and then tested for change in strength, diameter, and weight loss. The results obtained shows that corrosion affect steel reinforcement in concrete under HCl, H2SO4 and HNO3 with 15%,13% and 11% very high rate change in strength respectively. Also, the NaCl and HCl, were recorded with 15% and 11% very high rate effects on reduction/addition in diameter of steel reinforcement respectively. And finally, the HCl, and H2SO4 were recorded with 24.1% having the same and very high rate effects on reduction in weight (weight loss).
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Li, Ying Min, Lu Wang i Li Ping Liu. "Study on Constructional Reinforcement for the Foundation of Blast Furnace due to Temperature Effect". Applied Mechanics and Materials 94-96 (wrzesień 2011): 1545–48. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.1545.
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Based on the test and numerical analysis, the paper studied the constructional reinforcement of blast furnace foundation under the influence of concrete hydration and top temperature. The results indicate that constructional reinforcement should be thinner and have a small spacing. Stress concentration always appears around the corner and constraints of blast furnace foundation, where should be strengthened with constructional reinforcements. In order to prevent cracks caused by internal tensile stress during concrete hardening, it is necessary to place temperature reinforcement inside the foundation. Temperature effect should be considered at the circular area on top of blast furnace foundation and should be strengthened with constructional reinforcements.
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Li, Y.-F., S.-H. Chen, K.-C. Chang i K.-Y. Liu. "A constitutive model of concrete confined by steel reinforcements and steel jackets". Canadian Journal of Civil Engineering 32, nr 1 (1.02.2005): 279–88. http://dx.doi.org/10.1139/l04-093.
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In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.
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Krivenko, Pavlo, Igor Rudenko, Oleksandr Konstantynovskyi i Olha Boiko. "Prevention of steel reinforcement corrosion in alkali-activated slag cement concrete mixed with seawater". E3S Web of Conferences 280 (2021): 07004. http://dx.doi.org/10.1051/e3sconf/202128007004.
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Concretes mixed with seawater are characterised by enhanced performances, but action of chlorides and sulfates ensures the risk of reinforcement corrosion. Application of high consistency fresh concretes ensures changes in hardened concrete structure that causes the problem of steel reinforcement passive state ensuring. Thus mixing of plasticized concretes by seawater actualizes the search for means of steel corrosion prevention. Alkali-activated slag cements (further, AASC’s) reduce effect of ions Cl− and SO42− on steel reinforcement in concrete due to their exchange for ions OH− in the structure of zeolite-like alkaline hydroaluminosilicates. Complex additive «portland cement - calcium aluminate cement - clinoptilolite» was proposed to enhance the protective properties of AASC concretes to steel reinforcement. The results of DTA, X-ray diffraction, electron microscopy, microprobe analysis show that complex additive ensures to prevent steel reinforcement corrosion in AASC concrete mixed with seawater due to binding Cl− and SO42− ions in Kuzel’s salt in AASC hydration products and exchange of these aggressive ions with OH− ions in the structure of clinoptilolite. This effect of complex additive confirmed by surface state and the absence of mass loss of steel rebars embedded in plasticized AASC fine concrete mixed with seawater after 90 d of hardening.
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Gajdošová, Katarína, Viktor Borzovič, Adrián Valašík i Natália Gažovičová. "Application of GFRP Reinforcement in the Design of Concrete Structures and its Experimental Evaluation". Slovak Journal of Civil Engineering 26, nr 3 (1.09.2018): 11–15. http://dx.doi.org/10.2478/sjce-2018-0015.
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Abstract In the past, research on the use of FRP in civil engineering has been focused on strengthening existing structures where FRP reinforcements were applied to the surface of concrete elements. Recently, the application of FRP reinforcements has been studied to replace steel reinforcements for use in areas of increased environmental loads, with a need to exclude the corrosion of the reinforcement or to ensure the electromagnetic neutrality of the individual elements of the load-bearing structure. The GFRP reinforcement ratio was verified considering failure modes in flexure and the bond of the GFRP reinforcement with concrete. Besides classical reinforcements, GFRP has also been used in prestressed variants, and the possibility of its use as permanent formwork has been verified. In terms of extending the use of non-metallic reinforcements, it is important to note the long-term exposure and possible degradation of the mechanical properties.
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Kleshchevnikova, Varvara, Ksenia Strelets, Svetlana Belyaeva, Olga Nikonova, Yulia Volkova i Aleksandr Panfilov. "Dispersed reinforcement of columns of a high-rise building". E3S Web of Conferences 157 (2020): 06029. http://dx.doi.org/10.1051/e3sconf/202015706029.
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The article deals with the application of combined reinforcement of concrete with steel and basalt fibers. A model of a high-rise building was calculated in the LIRA-SAPR 2013 software. Design and characteristic strength of steel fiber and basalt fiber reinforced concretes to compression and tension and the initial elastic modulus were determined to calculate the model. Comparison of the effect of B40 concrete steel fiber reinforced concrete (SFRC) and basalt fiber reinforced concrete (BFRC) on column reinforcement was performed by comparing the required areas of reinforcement, as well as the percentage of reinforcement, taking into account crack resistance. The total area of reinforcement decreased with the addition of steel fiber by 36.9% and basalt fiber by 39.9%. The percentage of reinforcement also decreased, taking into account crack resistance, from 0.694 for columns with concrete B40 to 0.437 for SFRC columns and to 0.417 for BFRC columns. The addition of fiber increases the strength characteristics of concrete: compressive strength increased by 35.8% and 77.2%, tensile strength by 150.2% and 75.7%, crack resistance by 37% and 39.9%, the initial modulus of elasticity of the material increased by 8.7% and 3.7% for SFRC and BFRC respectively compared with concrete B40.
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Hack, Norman, Mohammad Bahar, Christian Hühne, William Lopez, Stefan Gantner, Noor Khader i Tom Rothe. "Development of a Robot-Based Multi-Directional Dynamic Fiber Winding Process for Additive Manufacturing Using Shotcrete 3D Printing". Fibers 9, nr 6 (8.06.2021): 39. http://dx.doi.org/10.3390/fib9060039.
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The research described in this paper is dedicated to the use of continuous fibers as reinforcement for additive manufacturing, particularly using Shotcrete. Composites and in particular fiber reinforced polymers (FRP) are increasingly present in concrete reinforcement. Their corrosion resistance, high tensile strength, low weight, and high flexibility offer an interesting alternative to conventional steel reinforcement, especially with respect to their use in Concrete 3D Printing. This paper presents an initial development of a dynamic robot-based manufacturing process for FRP concrete reinforcement as an innovative way to increase shape freedom and efficiency in concrete construction. The focus here is on prefabricated fiber reinforcement, which is concreted in a subsequent additive process to produce load-bearing components. After the presentation of the fabrication concept for the integration of FRP reinforcement and the state of the art, a requirements analysis regarding the mechanical bonding behavior in concrete is carried out. This is followed by a description of the development of a dynamic fiber winding process and its integration into an automated production system for individualized fiber reinforcement. Next, initial tests for the automated application of concrete by means of Shotcrete 3D Printing are carried out. In addition, an outlook describes further technical development steps and provides an outline of advanced manufacturing concepts for additive concrete manufacturing with integrated fiber reinforcement.
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Zhang, Lu, Ditao Niu, Bo Wen i Daming Luo. "Concrete Protective Layer Cracking Caused by Non-Uniform Corrosion of Reinforcements". Materials 12, nr 24 (17.12.2019): 4245. http://dx.doi.org/10.3390/ma12244245.
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The volume expansion of reinforcement corrosion products resulting from the corrosion of steel reinforcement embedded into concrete causes the concrete’s protective layer to crack or spall, reducing the durability of the concrete structure. Thus, it is necessary to analyze concrete cracking caused by reinforcement corrosion. This study focused on the occurrence of non-uniform reinforcement corrosion in a natural environment. The characteristics of the rust layer were used to deduce the unequal radial displacement distribution function of concrete around both angular and non-angular bars. Additionally, the relationship between the corrosion ratio and the radial displacement of the concrete around the bar was established quantitatively. Concrete cracking due to the non-uniform corrosion of reinforcements was simulated using steel bars embedded in concrete that were of uneven displacement because of rust expansion. The distribution of the principal tensile stress around the bar was examined. A formula for calculating the critical radial displacement at the point when cracking began was obtained and used to predict the corrosion ratio of the concrete cover. The determined analytical corrosion ratio agreed well with the test result. The effect factor analysis based on the finite element method indicated that increasing the concrete strength and concrete cover thickness delays concrete cracking and that the adjacent rebar causes the stress superposition phenomenon.
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Barabanshchikov, Yury, Svetlana Belyaeva, Arina Avdeeva i Maikel Perez. "Fiberglass Reinforcement for Concrete". Applied Mechanics and Materials 725-726 (styczeń 2015): 475–80. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.475.
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The features of the application of FRP reinforcement for concrete reinforcement. The results of mechanical tests. Shows the influence of the proportion of glass reinforcement on the physico-mechanical properties of rod fiberglass reinforcement.
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Boron, David. "Galvanized reinforcement for concrete". Anti-Corrosion Methods and Materials 42, nr 5 (maj 1995): 21–22. http://dx.doi.org/10.1108/eb007370.
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Cai, Hua, Feng Shuo Li i Xin Li. "Analysis of Concrete Pavements Characteristics of Oblique Distribution Forms of Prestressed Reinforcement". Applied Mechanics and Materials 97-98 (wrzesień 2011): 316–20. http://dx.doi.org/10.4028/www.scientific.net/amm.97-98.316.
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ABAQUS software is adopted. And the three-dimensional finite element models, respectively oblique and vertical reinforcements, are used for the calculation of the prestressed concrete pavement structure. The prestress is imposed on pavement by changing the temperature of reinforcements. Then through the analysis of mechanical behavior of the two kinds of prestressed reinforcement concrete pavements under the standard load. The results show that the oblique reinforcement pavement is flatter and the range of influnence is smaller. These data of the two kinds of pavements are provided for engineering design and construction.
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Lin, Wei, Jia Ping Liu i Jian Zhong Liu. "Influence of Reinforcement Placement on the Creep of Concrete". Key Engineering Materials 629-630 (październik 2014): 130–35. http://dx.doi.org/10.4028/www.scientific.net/kem.629-630.130.
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The creep of the concrete might cause comprehensive effect on the structure, such as stress redistribution and pre-stress relaxation. To better understanding the significant influence of the creep on the structure, the restriction of the reinforcement should be taken into account. In this paper, the creep of reinforced concrete was studied based on designed experiment with different concrete mixtures and reinforcement configurations. And Dischinger model was used to analysis the experiment results. It was found that, with the increasing of reinforcement ratio, the creep of all concretes could be reduced with a trend that the difference of the creep property between concrete mixtures would be delaminated by the reinforcement. And suggestion was proposed to modify the Dischinger model to better consider the influence of firm structure formed by rebar.
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Arel, Hasan Şahan, i Şemsi Yazıcı. "Concrete–reinforcement bond in different concrete classes". Construction and Building Materials 36 (listopad 2012): 78–83. http://dx.doi.org/10.1016/j.conbuildmat.2012.04.074.
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Ahlborn, Theresa M., i Timothy C. DenHartigh. "Comparative Bond Study of Stainless and High-Chromium Reinforcing Bars in Concrete". Transportation Research Record: Journal of the Transportation Research Board 1845, nr 1 (styczeń 2003): 88–95. http://dx.doi.org/10.3141/1845-10.
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Concrete bridge decks in corrosive environments have used several methods to prevent corrosion of the reinforcing steel including the use of alternative steels as reinforcement. While research has been conducted on corrosion resistance, very little information is available about the bond strength of alternative metallic reinforcement such as solid stainless steels and high-strength, high-chromium (HSHC) alloys. Therefore, the tensile bond strengths of three alternative metallic steel reinforcements in concrete are compared with conventional A615 Grade 60 steel reinforcement. Two types of stainless steel were considered, 316LN and 2205 duplex. An HSHC microcomposite bar was also considered. A total of 250 bond tests were performed with beam-end specimens similar to the ASTM A944 specimen. Bonded lengths of 4 to 12 in. were used for No. 4 and No. 6 reinforcing bars. Concrete clear cover for all tests was 1½ in. to produce cracking bond failure. No transverse reinforcement was present. The normal strength concrete was typical of that used in Michigan bridge decks. Statistical comparisons of bond test results with predicted values for bond strength of A615 reinforcement revealed there was no reason to believe the bond strength of the alternative metallic reinforcing bars was less than predicted. The conservatism of the current development-length relationships generally predicted lower bond strengths than were observed. Therefore, no modifications are suggested when estimating the development length of these reinforcements as a one-to-one replacement for A615 Grade 60 reinforcement, No. 4 to No. 6 bars, using standard development-length relationships.
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Melchers, Robert E. "Long-Term Durability of Marine Reinforced Concrete Structures". Journal of Marine Science and Engineering 8, nr 4 (18.04.2020): 290. http://dx.doi.org/10.3390/jmse8040290.
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The sustainability of reinforced concrete is critical, particularly for structures exposed to marine environments. Chlorides are implicated in causing or accelerating reinforcement corrosion and potentially earlier expensive repairs, yet there are many older reinforced concrete structures in good condition for many decades despite very high chloride levels at the reinforcement. The reasons for this are reviewed briefly, together with recent experimental work that better defines the role of chlorides. One is initiation of reinforcement corrosion but only through localized pitting at air-voids in concrete at the interface with the steel reinforcement. These tend to be small or negligible for high quality well-compacted concretes. The other role for chlorides has been shown, in experimental work, to accelerate the long-term loss of concrete alkali material. On the other hand, a review of practical experience shows that what has been termed chloride-induced reinforcement corrosion often is not that at all, but is the end-product of factors that impair the protective nature of the concrete. As reviewed herein, these include poor compaction, physical damage to concrete cover, concrete shrinkage, and alkali-aggregate reactions. The various observations presented are important for the proper understanding, analysis, and design of durable reinforced concrete structures exposed to chloride-rich environments.
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Korotkikh, D., D. Panfilov i A. Polikutin. "Modeling of Aerated Cement Concrete Structure and Increasing its Crack Resistance". Materials Science Forum 945 (luty 2019): 951–56. http://dx.doi.org/10.4028/www.scientific.net/msf.945.951.
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In this article is described a problem of increasing crack resistance of aerated cement concrete. Authors, having a model of concrete’s structure, made a disclosure of ratios for calculation of parameters the aerated concrete with disperse reinforcement. These ratios show data about change of structure parameters of aerated concretes with disperse reinforcement such as different density by variation of factors water-cement ratio, percent of reinforcement, ratio between dosing of cement and sand. Concrete’s cracking resistance was evaluated by compressive strength and parameter KIc. As result of experimental data processing authors got regression’s equations, which adequately describe changes of fracture toughness and compressive strength of aerated cement concrete (foam concrete) with density 1200 kg/m3 and 1400 kg/m3 in limits of factor area. There was shown a possibility of two-time increasing of fracture toughness and strength of aerated cement concrete with disperse reinforcement its structure by rough basalt fiber.
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Duy Phan Nguyen i Viet Quoc Dang. "Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams". International Journal of Engineering and Technology Innovation 11, nr 1 (20.01.2021): 01–11. http://dx.doi.org/10.46604/ijeti.2021.6660.
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In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.
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Tang, Xian Xi, Xian Zhou Tang, Yue Xu i Wei Guo. "Analysis of Reasonable Reinforcement Structure of Concrete Bridge Deck". Advanced Materials Research 255-260 (maj 2011): 1248–51. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.1248.
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In order to study the impact of reforcement stress and concrete cracking of concrete bridge deck caused by the difference of reforcement diameter and spacing, the sub-model analysis was adopted, the bottom horizontal reforcement stress and concrete cracking affected by different diameter and spacing were analysised. The analysis results indicated that When the reforcement spacing was greater than 10cm, the concrete under the most unfavorable position of load would crack; in the vehicle the most unfavorable position, the concrete would crack; When the reinforcement specing was not more than 10cm, if the bar diameter was greater than a certain value, the concrete would not crack. Meanwhile, with the increase of reforcement diameter, steel stress decreased, the possibility of concrete cracking reduced. Combined with the analysis results, the reasonable diameter and spacing of underlying transverse reinforcement of concrete bridge deck were given, the diameter and spacing of other reinforcements of the bridge deck were recommended.
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Poluektova, Valentina Anatolyevna. "Fine-Grained Polymer-Cement Basalt Fibrous Concrete for 3D Printing". Solid State Phenomena 299 (styczeń 2020): 227–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.227.
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The construction concrete printing requires new approaches at reinforcement performing. Only successful integration of the existing reinforcement systems will provide for the opportunity to design concrete structures and make objects with the help of additive technologies. The paper dwells upon the issues of possibilities and the efficiency of disperse reinforcement with basalt fibers. It presents a composition of a composite material for 3D printing of a type of fine-grained fibrous concretes with the required technological properties: a necessary plasticity and a high plastic strength for printing large-dimensioned items and structures without timbering by means of extrusion with a high material adhesion between the layers and controlled setting periods. The author studied a possibility to reclaim basalt fiber production wastes as a high-disperse fibrous filler for the reinforcement of polymer-modified concretes. The article provides the dependence of plastic strength on the fiber content in concrete. The authors consider the influence of components and the mechanism of modifying disperse particles of basalt fibrous concrete at obtaining the material for 3D printing. The obtained polymer-modified basal fibrous concrete has a good impact resistance, low water absorption and high crack resistance.
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Shen, Jiansheng, Xi Gao, Bo Li, Kun Du, Ruoyu Jin, Wei Chen i Yidong Xu. "Damage Evolution of RC Beams Under Simultaneous Reinforcement Corrosion and Sustained Load". Materials 12, nr 4 (20.02.2019): 627. http://dx.doi.org/10.3390/ma12040627.
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To accurately obtain the performance of concrete structures in coastal regions, it is necessary to correctly understand the damage evolution law of reinforced concrete (RC) members under real working conditions. In this paper, four RC beams, subjected to different levels of corrosion and sustained load, are first tested. Reinforcement corrosion coupled with sustained load increases the number and width of cracks at the soffit of beams but decreases their loading capacities. Crack width of the corroded beam under 50% of designed load is two times of that under 30% of designed load. Residual loading capacities of the corroded beams subjected to 30% and 50% of designed load are 87.5% and 81.8% of the control beam. A finite element model is developed for the corroded RC beams. Due to less confinement, concrete below and at the sides of reinforcements is subjected to a higher stress, compared to concrete above the reinforcements. Corrosion expansion of reinforcements is successfully modelled by a temperature-filed method, as it properly simulates the damage evolution of the corroded RC beams. As a result, concrete cracking, caused by the reinforcement corrosion, is well captured. Coupling reinforcement corrosion with sustained load significantly increases the damage level in RC beams, particularly for those subjected to a high sustained load. The whole damage evolution process of concrete cracking due to corrosion expansion under the coupling effect of sustained loading and environment can be simulated, thus providing a reference for the durability evaluation, life prediction, and numerical simulation of concrete structure.
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Nesvetaev, Grigorii, Evgenii Lesniak, Aleksei Kolleganov i Nikita Kolleganov. "On the Influence of Cross-Section and Reinforcement of Reinforced Concrete Constructions on the Concentration of Coarse Aggregate in Concrete with Frame Structure". Materials Science Forum 1011 (wrzesień 2020): 66–71. http://dx.doi.org/10.4028/www.scientific.net/msf.1011.66.
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Concretes with frame structure produced by using the technology of separate concreting by immersing a coarse aggregate in a low-viscosity mortar matrix due to an increased concentration of coarse aggregate have an increased E-modulus, reduced creep coefficient and cement volume in concrete compared to traditional vibrational compaction concretes. Production concrete using separate concreting technology by immersing a coarse aggregate in a mortar matrix with low-viscosity allows to obtain a frame structure of concrete with a concentration of coarse aggregate up to 0.7 when a voidness of coarse aggregate is equal 0.28. The real concentration of coarse aggregate in a concrete structure depends on the particle size of the coarse aggregate, the cross-section dimensions of the structure, and the reinforcement coefficient. The influence of geometric dimensions and the coefficient of reinforcement on the concentration of coarse aggregate in the concrete with frame structure is studied. The concentration of coarse aggregate decreases with the growth of the S/V modulus (S – area, m2, V – volume, m3) and the reinforcement coefficient, but the decrease in the E-modulus does not exceed 5%. Conclusion: regardless of the type of construction and reinforcement, the concrete of the frame structure must have a sufficiently high uniformity of deformation properties.
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Dauji, Saha. "Reinforcement corrosion in coastal and marine concrete: A review". Challenge Journal of Concrete Research Letters 9, nr 2 (8.06.2018): 62. http://dx.doi.org/10.20528/cjcrl.2018.02.003.
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Concrete is used as a structural material for construction of buildings, jetties, harbors, etc. in many coastal and marine locations. The reinforcement used in concrete is susceptible to corrosion, resulting in loss of steel area, loss of bond, expansion of the reinforcement volume leading to cracking or spalling of concrete. Marine environment induces higher corrosion of reinforcement, compared to in-land locations. Concrete exposed to tidal fluctuations, or to the action of waves and currents are among the most severely affected. Corrosion of reinforcement in concrete is of major concern in coastal and marine environment. Control and monitoring of corrosion is a big challenge to engineers. In the recent years, different investigators reported their studies in this area. Depending on the severity of the exposure conditions, different corrosion inhibitors and protection methods have been attempted with varying degrees of success. The present article presents a generic review of the corrosion issues in marine concrete. Drawing from the experiences of the various researchers, the corrosion measurements, and corrosion control schemes, including use of coated reinforcements and corrosion inhibitors are discussed. The durability performance based design of concrete in the probabilistic framework and the life cycle cost analysis for durability design decisions have been identified as the future direction of corrosion protection of coastal and marine structures.
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Silva, T. F., i J. C. Della Bella. "Design of compression reinforcement in reinforced concrete membrane". Revista IBRACON de Estruturas e Materiais 5, nr 6 (grudzień 2012): 820–47. http://dx.doi.org/10.1590/s1983-41952012000600007.
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This paper presents a method to design membrane elements of concrete with orthogonal mesh of reinforcement which are subject to compressive stress. Design methods, in general, define how to quantify the reinforcement necessary to support the tension stress and verify if the compression in concrete is within the strength limit. In case the compression in membrane is excessive, it is possible to use reinforcements subject to compression. However, there is not much information in the literature about how to design reinforcement for these cases. For that, this paper presents a procedure which uses the model based on Baumann's [1] criteria. The strength limits used herein are those recommended by CEB [3], however, a model is proposed in which this limit varies according to the tensile strain which occur perpendicular to compression. This resistance model is based on concepts proposed by Vecchio e Collins [2].
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Trapko, Tomasz, i Michał Musiał. "Effect of PBO–FRCM Reinforcement on Stiffness of Eccentrically Compressed Reinforced Concrete Columns". Materials 13, nr 5 (9.03.2020): 1221. http://dx.doi.org/10.3390/ma13051221.
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This paper examines the effect of PBO (P-phenylene benzobisoxazole)–FRCM (Fabric Reinforced Cementitious Matrix) reinforcement on the stiffness of eccentrically compressed reinforced concrete columns. Reinforcement with FRCM consists of bonding composite meshes to the concrete substrate by means of mineral mortar. Longitudinal and/or transverse reinforcements made of PBO (P-phenylene benzobisoxazole) mesh were applied to the analyzed column specimens. When assessing the stiffness of the columns, the focus was on the effect of the composite reinforcement itself, the value and eccentricity of the longitudinal force and the decrease in the modulus of elasticity of the concrete with increasing stress intensity in the latter. Dependences between the change in the elasticity modulus of the concrete and the change in the stiffness of the tested specimens were examined. The relevant standards, providing methods of calculating the stiffness of composite columns, were used in the analysis. For columns, which were strengthened only transversely with PBO mesh, reinforcement increases their load capacity, and at the same time, the stiffness of the columns increases due to the confinement of the cross-section. The stiffness depends on the destruction of the concrete core inside its composite jacket. In the case of columns with transverse and longitudinal reinforcement, the presence of longitudinal reinforcement reduces longitudinal deformations. The columns failed at higher stiffness values in the whole range of the eccentricities.
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Pokorný, P., J. Čech, P. Tej i M. Vokáč. "The influence of total reinforcement anchorage length on misinterpretation of the impact of hot-dip galvanised steel corrosion on its bond strength with concrete". Koroze a ochrana materialu 60, nr 1 (1.03.2016): 13–20. http://dx.doi.org/10.1515/kom-2016-0003.
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Abstract To begin with, the intorduction of this paper summarises literature sources that wrongly interpret results of the bond strength between hot-dip galvanised reinforcements and concrete. The influence of the total reinforcement anchorage length on the bond strength results assessment was studied in detail. The numeric analysis of beam models with various testing anchorage lengths (the analysis input data comprised the results of previous bond strength tests carried out in a laboratory) unambiguously confirmed that when the bond strength between concrete and hot-dip galvanised reinforcement with a sufficient test anchorage length is tested in a beam test, the negative impact of the coating corrosion on bond strength with concrete may be biased. It is more objective to test bond strength with concrete in a pull-out test where a very short test reinforcement anchorage length is set out as a standard.
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Zhu, Guo Liang. "The Analysis of Relationship between Stirrup and Longitudinal Reinforcement with Regression Analysis". Applied Mechanics and Materials 438-439 (październik 2013): 342–45. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.342.
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Regional confined concrete is a method which can strengthen constraint in the most needed position, it can make concrete, longitudinal reinforcement and transverse stirrup to form a more effective binding, and provide a stronger restraint in required regional giving full play the role of constraints. In the result analysis of the regional confined column specimen load test, we found that longitudinal reinforcement and stirrup strains have certain relationship. This article analyses the relationship between the two from the stirrup and longitudinal reinforcements strains in the contingency load, references are provided for the further development of regional confined concrete theory. Taking the two specimens as examples, the regression analysis was carried on between longitudinal reinforcement and stirrup strain, the relationship equation was obtained
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Baša, Nikola, Mladen Ulićević i Radomir Zejak. "Experimental Research of Continuous Concrete Beams with GFRP Reinforcement". Advances in Civil Engineering 2018 (18.10.2018): 1–16. http://dx.doi.org/10.1155/2018/6532723.
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Continuous beams are often used within RC structures, which are exposed to aggressive environmental impact. The use of the fiber-reinforced polymer (FRP) reinforcement in these objects and environments has a big significance, taking into account tendency of steel reinforcement to corrode. The main aim of these research studies is to estimate ability of continuous beams with glass FRP (GFRP) reinforcement to redistribute internal forces, as a certain way of ductility and desirable behaviour of RC structures. This paper gives the results of experimental research of seven continuous beams, over two spans of 1850 mm length, cross-section of 150 × 250 mm, that are imposed to concentrated forces in the middle of spans until failure. Six beams were reinforced with different longitudinal GFRP and same transverse GFRP reinforcements, and one steel-reinforced beam was adopted as a control beam. The main varied parameters represent the type of GFRP reinforcement and ratio of longitudinal reinforcement at the midspan and at the middle support, i.e., design moment redistribution. The results of the research have shown that moment redistribution in continuous beams of GFRP reinforcement is possible, without decreasing the load-carrying capacity, compared to elastic analysis. The test results have also been compared to current code provisions, and they have shown that the American Concrete Institute (ACI) 440.1R-15 well predicted the failure load for continuous beams with GFRP reinforcement. On the contrary, current design codes underestimate deflection of continuous beams with GFRP reinforcement, especially for higher load levels. Consequently, a modified model for calculation of deflection is proposed.
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Kotes, Peter, Josef Vican, Miroslav Brodnan i Ružica Nikolič. "Reliability of Existing Concrete Bridges from the Aspect of the Reinforcement Corrosion". Key Engineering Materials 691 (maj 2016): 119–28. http://dx.doi.org/10.4028/www.scientific.net/kem.691.119.
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The quality and durability of the concrete structures are affected by many degradation processes. The reliability of existing bridge structures is significantly affected by numerous factors, from which the reinforcement and structural steel corrosion, together with effect of traffic action, are the most important. Corrosion is the destructive attack on metal by chemical or electrochemical reaction with its environment. In the case of reinforced concrete (RC) structures, the most known degradation process is corrosion of reinforcement. RC members have to fulfill the conditions given in Eurocode [1, 2]. Horizontal beams are mainly subjected to bending and shear. The paper deals with reinforcement corrosion of main longitudinal reinforcements (reinforcement against bending) and its influence on the moment resistance of the existing bridge concrete structures. The two types of active stage calculation of corrosion were considered in this paper. The length of passive stage was not known, so it was calculated backwards.
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Pidun, Kevin, i Thomas Gries. "Shaped Textile Reinforcement Elements for Concrete Components". Advanced Materials Research 747 (sierpień 2013): 415–19. http://dx.doi.org/10.4028/www.scientific.net/amr.747.415.
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By now the application of Textile Reinforced Concrete (TRC) for facade constructions can be considered as state of the art. Especially ventilated curtain walls made of TRC and sandwich elements made in combination of TRC-layers and foam cores recently are realized in pilot projects which are predominantly located in Aachen, Germany. The Life funded Insu-Shell façade of the Institute fuer Textiltechnik (ITA) of RWTH Aachen University gives an example of such a pilot project. Furthermore, a pedestrian bridge has been built in Albstadt, Germany. The enormous potential of TRC-applications is shown in these practical projects. All projects have been completed successfully and present good results in terms of the surface quality, the design freedom, the wall thinness and the ecological performance. A networked process chain was aimed at and approached and finally implemented. Apart from this, all these projects incorporating impregnated textile reinforcements reveal unanswered questions regarding production of shaped reinforcement elements, their ability to bear loads and their durability. Particularly the transformation of a 2D-warp-knit fabric to a reinforcement element (textile reinforcement cage) is a challenge, which needs to be addressed further. Since the beginning of 2012 a new transfer project called Shaped textile reinforcement elements for concrete components (T08) within the framework of the Collaborative Research Center 532 `Textile Reinforced Concrete - Development of a new technology` is funded. That challenge is to be solved in the T08 project in cooperation with Institutes from the RWTH Aachen University and industry partners led by the Institute of Structural Concrete of RWTH Aachen University.
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Choi, Hyun Ki. "The Effect of Anchorage Strength with Anchorage Capacity in Flat Plate". Key Engineering Materials 627 (wrzesień 2014): 245–48. http://dx.doi.org/10.4028/www.scientific.net/kem.627.245.
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The punching shear on the flat plate slab-column connection can bring about the reason of the brittle punching shear failure which may result of collapsing the whole structure. From the development of residential flat plate system, the shear reinforcement is developed for preventing the punching shear. This study proposed 3 reinforcements that are increased to bond capacity using lateral bar, the structure test is performed. As performed test result, because slabs not keep enough bond length, slab is failed before shear reinforcement's yield strength duo to anchorage of slip. According to result, FEM analyzed an effect of slab thickness and concrete compressive. The study suggests shear strength formula that possible a positive shear reinforcement in slab-column connection.
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Bywalski, Czesław, i Mieczysław KamiIński. "RHEOLOGICAL STRAINS IN CONCRETE MODIFIED WITH STEEL FIBRE REINFORCEMENT". Journal of Civil Engineering and Management 19, nr 5 (29.10.2013): 656–64. http://dx.doi.org/10.3846/13923730.2013.803497.
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This paper discusses the rheological properties of normal (ordinary) strength concrete. The results of tests aimed at determining the creep strains and shrinkage strains in normal strength concretes modified with steel fibre reinforcement are presented. The tests were divided into three groups. Steel fibre reinforced concretes (SFRCs) with a different composition were studied in each of the groups. Hook steel fibres, 50-mm long and 0.8 mm in diameter, were used in the tested SFRCs. The latter had an average compressive strength of 35.17–59.18 MPa and a steel fibre content of 0, 25, 35, 50 and 65 kg per 1 m3 of the concrete mixture respectively. Functional dependences for the increase in shrinkage and creep strains over time are given. The problem of the effect of aggregate grading on creep strains is addressed. Conclusions concerning the rheological deformability of steel fibre reinforced concrete are drawn.
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Chvertko, P. N., N. D. Goronkov, N. A. Vinogradov, S. M. Samotryasov i V. Yu Sysoev. "Resistance butt welding of concrete reinforcement in construction site". Paton Welding Journal 2014, nr 3 (28.03.2014): 45–48. http://dx.doi.org/10.15407/tpwj2014.03.08.
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