Статті в журналах: "High strength concrete Fire-testing"

1

Liu, Feng, Gui Xuan Chen, and Li Juan Li. "Performance of Rubberized High Strength Concrete after Fire." Advanced Materials Research 163-167 (December 2010): 1403–8. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1403.

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The effects of recycled rubber powder on working abilities, density and compressive strength of high strength concrete (HSC) at room temperature were studied in this paper. The characteristics of rubberized high strength concrete (RHSC) after fire was investigated by surface observation, weight loss and retained strength testing. The sieve number of rubber powder used in test is No.40 (420μm), No.60 (250µm) and No.80 (178µm), and the content of rubber powder filled in RHSC is 1%, 2%, 3% and 4% with respect to cementation material respectively. Test results show that the increase in rubber powder content reduces the concrete strength, while the decrease in compressive strength of RHSC is less than 10% when the content of rubber powder is within 2%. RHSC with small content of rubber (1%) can restrain the spalling failure of concrete under high temperature.

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Kwon, Ki Seok, Heung Youl Kim, Seung Un Chae, and Bum Yean Cho. "A Study on the Collapse Mechanism of High Strength Concrete Columns Apply to Fiber-Cocktail." Applied Mechanics and Materials 784 (August 2015): 385–90. http://dx.doi.org/10.4028/www.scientific.net/amm.784.385.

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More high-rise structures are currently being constructed and correspondingly, the compressive strength of concrete has been increased. However, compared to conventional strength concrete the high strength concrete (HSC) exhibits coarse inner pore structure which blocks escape routes of vapour generated in the event of fire. This results in spalling and subsequently, are responsible for fire vulnerability of the structure. In addition, spalling phenomena is also affected by the section dimensions of HSC which is also another crucial factor from socio-economic considerations. Thus, this study was carried out to evaluate the fire resistance performance of hybrid fiber (i.e. steel-polypropylene-fibre)-reinforced HSC columns with different cross-section dimensions. The result of the fire resistance performance testing using 100MPa concrete showed that delay to failure was observed by approximately 76 per cent.

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3

Shallal, Muhaned A., and Aqil Mousa K. Al Musawi. "Tests of Residual Shear Transfer Strength of Concrete Exposed to Fire." Archives of Civil Engineering 64, no. 2 (December 31, 2018): 187–99. http://dx.doi.org/10.2478/ace-2018-0024.

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AbstractReinforced concrete is one of the most widely used structural components about which much scientific research has been conducted; however, some of its characteristics still require further research. The main focus of this study is the effect of direct fire on the shear transfer strength of concrete. It was investigated under several parameters including concrete strength, number of stirrup legs (the steel area across the shear plane), and fire duration. The experimental program involved the testing of two sets (groups) of specimens (12 specimens each) with different concrete strengths. Each set contained specimens of two or four stirrup legs exposed to direct fire from one side (the fire was in an open area to simulate a real-life event) for a duration of one, two, and three hours. The results of the comparison showed the importance of using high-performance concrete (instead of increasing the number of stirrup legs) to resist shear stress for the purpose of safety. A significant reduction in shear strength occurred due to the deterioration of the concrete cover after three hours of direct fire exposure.

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4

Lin, Ching Chang, Cheng Hou Liu, and Cho Liang Tsai. "Study on the Behaviors of CFRP Confining Concrete Specimens Exposed to Fire, Acid and Alkaline Environments." Applied Mechanics and Materials 147 (December 2011): 32–36. http://dx.doi.org/10.4028/www.scientific.net/amm.147.32.

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This paper studies the behaviors of carbon fiber reinforced plastics (CFRP) confining concretes exposed to fire, acid or alkaline environments. The concrete specimens wrapped with CFRP were exposed to different high temperatures or submerged to acid or alkaline solutions with different concentrations. All the specimens were then loaded under uni-axial compression test. The strength and ductility of concrete specimen were evaluated. The environmental influences on the confining effects of CFRP were also investigated. The results indicate that CFRP reinforcements can provide good confinements for concrete specimens, so both the strength and ductility of concrete specimens can be significantly increased. But CFRP confining concrete specimens exposed to fire environments over 300°C will lose some of the confinements and the strength and ductility are significantly decreased. When adhered by fireproof material, CFRP confining concrete specimens exposed to fire environments will not lose all the confinements and still retain most of their original strengths and strains. The fireproof material can really protect CFRP confining concretes from high temperatures. The fire resistance effect of fireproof material depends on its thicknesses and the fire environments. The results also show that CFRP confining concrete specimens when submerged into acid or alkaline environments will lose some of the confining effect of CFRP. The higher the concentration or the longer the soaking period of acid or alkaline environments, the more the CFRP material is damaged and thus CFRP confining concrete specimens lose some of their strenghs.

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5

Kodur, Venkatesh KR. "Innovative strategies for enhancing fire performance of high-strength concrete structures." Advances in Structural Engineering 21, no. 11 (January 19, 2018): 1723–32. http://dx.doi.org/10.1177/1369433218754335.

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High-strength concrete is being increasingly used in a number of building applications, where structural fire safety is one of the primary design considerations. Many research studies clearly indicate that the fire performance of high-strength concrete is different from that of normal-strength concrete and that high-strength concrete may not exhibit same level of performance as normal-strength concrete under fire conditions. This article outlines key characteristics that influence the performance of high-strength concrete structural members under fire conditions. Data generated in previous experimental and numerical studies are utilized to illustrate various factors that influence fire performance of high-strength concrete structural members. Based on the published data, observations and trends on the behavior of high-strength concrete members, innovative strategies for mitigating spalling and enhancing fire resistance of high-strength concrete structural members are proposed.

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6

Kodur, VKR. "Performance of high strength concrete-filled steel columns exposed to fire." Canadian Journal of Civil Engineering 25, no. 6 (December 1, 1998): 975–81. http://dx.doi.org/10.1139/l98-023.

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Results from an experimental program on the behaviour of high strength concrete-filled steel hollow structural section (HSS) columns will be presented for three types of concrete filling. A comparison will be made of the fire-resistance performance of HSS columns filled with normal strength concrete, high strength concrete, and steel-fibre-reinforced high strength concrete. The various factors that influence the structural behaviour of high strength concrete-filled HSS columns under fire conditions are discussed. It is demonstrated that, in many cases, addition of steel fibres into high strength concrete improves the fire resistance and offers an economical solution for fire-safe construction.Key words: high strength concrete, steel columns, fire-resistance design, high-temperature behaviour, concrete-filled steel columns.

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7

Choi. "Fire resistance assessment of high strength segment concrete depending on PET fiber amount under fire curves." Journal of Korean Tunnelling and Underground Space Association 16, no. 3 (2014): 311. http://dx.doi.org/10.9711/ktaj.2014.16.3.311.

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8

Nguyen, Kate TQ, Tuan Ngo, Priyan Mendis, and David Heath. "Performance of high-strength concrete walls exposed to fire." Advances in Structural Engineering 21, no. 8 (September 26, 2017): 1173–82. http://dx.doi.org/10.1177/1369433217732500.

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High-strength concrete is becoming very popular around the world due to its many advantages over normal-strength concrete. There are significant behavioural differences between high-strength concrete and normal-strength concrete, most notably the brittleness and sudden spalling under elevated temperatures, whereby pieces of hardened concrete explosively dislodge. Although all high-rise and even many medium-rise buildings have high-strength concrete walls, the spalling of high-strength concrete walls in fire has generally been ignored by the designers and the fire resistance of walls has been calculated using the rules specified for normal-strength concrete. Catastrophic failures could occur due to this ignorance of an important issue. Major design codes including the American and Australian Codes do not cover spalling adequately. Even the Eurocode rules are based on limited research. After a brief discussion on the present design practice, this article presents a summary of spalling research. The relevant results from a comprehensive study conducted at the University of Melbourne are briefly discussed. The authors are not aware of any other comprehensive research projects covering the fire behaviour of normal-strength concrete and high-strength concrete walls exposed not only to standard fires but also hydrocarbon fires. The results showed that spalling in high-strength concrete is more significant when subjected to hydrocarbon fire compared to normal-strength concrete. The level of compressive load on the panels was also found to have a significant effect on the fire performance of the high-strength concrete panels. The finite analysis element program, ANSYS, was used to model the concrete walls subjected to load and fire (both ISO834 Standard fire and hydrocarbon fire). The test results were used to validate the computer model.

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9

Razak, Siti Nooriza Abd, Nasir Shafiq, Laurent Guillaumat, Mohamed Mubarak Abdul Wahab, Syed Ahmad Farhan, Nadzhratul Husna, and Fouad Ismail Ismail. "Effect of Heating Duration at High Temperature on the Strength and Integrity of Fly Ash-Based Geopolymer Concrete." IOP Conference Series: Earth and Environmental Science 945, no. 1 (December 1, 2021): 012063. http://dx.doi.org/10.1088/1755-1315/945/1/012063.

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Abstract Fire is one of the most severe environmental conditions that concrete structures might be subjected to, especially in closed conduct structures, such as tunnels. Concrete in general can withstand fire but its properties degrade when exposed to fire at high temperatures. The effect of heating duration, at a high temperature, on the performance of fly ash-based geopolymer concrete is presented. Cubes of low, medium and high strength grades of geopolymer concrete that had been cured for 28 days, were exposed to a fire flame at 1000 °C for 30, 60, 90, 120, 150 and 180 min. After the fire exposure, the cubes were cooled to the ambient temperature before further testing. A visual observation was performed on the cubes to detect any colour change, cracking and spalling. The losses of mass and residual compressive strength of the cubes were recorded. The results showed that as the heating duration increased from 30 to 90 min, the compressive strength of the cubes also increased. Contrarily, the compressive strength decreased as the heating duration increased beyond 90 min indicating that the extended heating duration induced the loss of free water and decomposition of aluminosilicate products in geopolymer concrete. The evaporation of water by virtue of the heating for the extended duration, at high temperature, led to a loss in the mass of concrete. The findings suggest that geopolymer concrete was able to sustain its structural integrity without any noticeable spalling and hence, it can be classified as a fire-resistant material.

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10

Hager, Izabela, and Katarzyna Mróz. "Role of Polypropylene Fibres in Concrete Spalling Risk Mitigation in Fire and Test Methods of Fibres Effectiveness Evaluation." Materials 12, no. 23 (November 23, 2019): 3869. http://dx.doi.org/10.3390/ma12233869.

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The explosive behaviour of concrete in fire is observed in rapidly heated concrete. The main factors controlling the occurrence of spalling are related to the material’s low porosity and high density as well as the limited ability to transport gases and liquids. Thus, for high-strength, ultrahigh-strength, and reactive powder concrete, the risk of spalling is much higher than for normal-strength concrete. The paper presents the discussion on the leading hypothesis concerning the occurrence of concrete spalling. Moreover, the methods for spalling prevention, such as polypropylene fibre application, which has been found to be an effective technological solution for preventing the occurrence of spalling, are presented. Various tests and testing protocols are used to screen concrete mixes propensity toward spalling and to evaluate the polypropylene fibres’ effectiveness in spalling risk mitigation. The most effective testing methods were selected and their advantages were presented in the paper. The review was based mainly on the authors’ experiences regarding high performance concrete, reactive powder concrete testing, and observations on the effect of polypropylene fibres on material behaviour at high temperature.

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11

Lalu, O., R. Darmon, and T. Lennon. "Spalling of high strength concrete in fire." IOP Conference Series: Materials Science and Engineering 1138, no. 1 (April 1, 2021): 012027. http://dx.doi.org/10.1088/1757-899x/1138/1/012027.

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12

Price, W. F., and J. P. Hynes. "In-situ strength testing of high strength concrete." Magazine of Concrete Research 48, no. 176 (September 1996): 189–97. http://dx.doi.org/10.1680/macr.1996.48.176.189.

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13

Chen, Guo Can, Zhi Sheng Xu, and Wei Hong Tang. "Residual Strength of Super High Strength Concrete Used Stone-Chip after Exposure to High Temperatures." Advanced Materials Research 374-377 (October 2011): 2456–60. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.2456.

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This paper presents the results of experimental studies on the residual compressive strength of concrete produced with stone-chip as fine aggregates with the compressive strengths of unheated specimen ranging from 45.8 to 129.5MPa after exposure to high temperatures and the experimental parameters being the temperature, admixtures, and PP fiber. Specimens were heated in an electric furnace for 4h to high temperatures ranging from 150 to 960°C. Experimental results showed that the compressive strengths of super high strength concrete used stone-chip (abbreviated to SHSCUS) and normal strength concrete used stone-chip (abbreviated to NSCUS) after exposure to elevated temperatures changed in the manners different from that of normal strength concrete, which reached their peak at about 400°C, and the presence of pp ﬁbers in SHSCUS concrete could reduce the risk of spalling at the high temperatures and the peak value after fire.

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14

Xiao, Jian Zhuang, Qing Hai Xie, Yi Zhao Hou, and Zhi Wei Li. "Reliability Analysis of High-Strength Concrete Columns during a Fire." Key Engineering Materials 629-630 (October 2014): 273–78. http://dx.doi.org/10.4028/www.scientific.net/kem.629-630.273.

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A reliability analysis was conducted on high-strength concrete (HSC) columns during a fire. The influences of fire’s randomness and explosive spalling of concrete were investigated. The fire resistance for axial loading capacity of HSC columns was in terms of steel yield strength and concrete compressive strength with considering the effect of elevated temperatures. The load random variables included dead load and sustained live load. The JC method was applied to calculate the reliability index of the fire resistance of axially loaded HSC columns. It was found that the randomness of fire and explosive spalling of concrete had a significant influence on reliability of HSC columns.

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15

Araújo, Rafael Campos de Alencar, William Menezes da Silva, Tiago Ancelmo de Carvalho Pires, and José Jéferson do Rêgo Silva. "Compressive strength assessment of high strength concrete after fire using ultrasonic test method." Research, Society and Development 11, no. 11 (August 15, 2022): e63111132719. http://dx.doi.org/10.33448/rsd-v11i11.32719.

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This paper aims to evaluate the non-destructive ultrasonic pulse velocity (UPV) test method for determining the compressive strength of high strength of concrete (HSC) after fire. The compressive strength was determined through destructive cylinder test and by measuring ultrasonic pulse velocity. A total of 10 equations that relate compressive strength of concrete to UPV were evaluated in a total of 20 concrete samples. None of the equations were well suited for the case of HSC. The paper proposed a new equation and the UPV test showed suitable to assessment post-fire damaged HSC.

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16

Kapsalis, Panagiotis, Tine Tysmans, Svetlana Verbruggen, and Thanasis Triantafillou. "Preliminary High-Temperature Tests of Textile Reinforced Concrete (TRC)." Proceedings 2, no. 8 (June 29, 2018): 522. http://dx.doi.org/10.3390/icem18-05416.

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Fire-testing of Textile Reinforced Concrete (TRC) is an interesting field in which quite limited research has been conducted so far. In this paper some preliminary tests are presented, where mortars used as binders are heated to 850 °C and their residual strength is tested, while the Ultrasonic Pulse Velocity (UPV) is also measured, before and after heating, and compared. Additionally, TRC specimens are subjected to flame exposure with a simple set-up and the residual strength is also tested by flexural tests. It is concluded that even with simple set-ups, interesting results can be obtained regarding the structural degradation of the material.

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17

Johnson, Claude D., and S. Ali Mirza. "Confined capping system for compressive strength testing of high performance concrete cylinders." Canadian Journal of Civil Engineering 22, no. 3 (June 1, 1995): 617–20. http://dx.doi.org/10.1139/l95-070.

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This paper presents a simple, inexpensive confined cap testing method which can be employed in the compressive strength testing of high performance concrete cylinders. An inexpensive customized cylinder capping apparatus and standard concrete laboratory testing equipment are employed. The paper describes the capping apparatus, capping and testing procedures, as well as test results for concrete compressive strengths up to and exceeding 100 MPa. Key words: capping, capping confinement, compressive strength, cylinders, end condition, grinding, high-strength concrete, specimen size, testing.

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18

Yu, Shui Jun, Peng Fei Zhang, Xiao Fang Yang, Hong Zhao, and Xiao Li Chen. "Refractory Performance Study on Foamed Concrete and Concrete." Applied Mechanics and Materials 357-360 (August 2013): 1034–38. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.1034.

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Foam concrete is used in building energy saving and heat preservation project, and its refractory performance is very important to improve the fire resistance ability of the building. In this paper, fireproof property of the foamed concrete were studied.In the simulation fire conditions, compressive strength value of foamed concrete in different density, different calcination time, and different water content cases were determined first, then influence of these conditions on the foamed concrete refractory performance were researched. The results showed that foamed concrete compressive strength loss rate increase with density decreases in fire cases; Density of 300kg/m3 and 800kg/m3 foam concrete block, calcinated under 800°C fire in 20 min, its compressive strength loss rate were 66.3% and 25.5% respectively; The same density of foamed concrete compressive strength gradually reduce with the increase of calcining time; Moisture content on the different density of foam concrete affect differently on the fire safety. Foamed concrete is incombustible, but its compressive strength reduced due to fire inflammable material of high temperature calcined.

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19

Peng, Gai Fei, and Yan Teng. "Fire Resistance of Ultra-High-Strength Concrete: a Review." Key Engineering Materials 477 (April 2011): 333–39. http://dx.doi.org/10.4028/www.scientific.net/kem.477.333.

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This paper presents a review of advances in research on fire resistance of high-strength concrete (HSC) and ultra-high-strength concrete (UHSC). Further research needs in the near future on UHSC, especially on reactive powder concrete (RPC), are also discussed. It is commonly recognized that HSC suffers strength loss in a manner basically similar to that of normal strength concrete. But the main problem of HSC is explosive spalling under high temperature, which can be solved by employing either polymer fiber or steel fiber. Since RPC200 is a type of RPC which has been successfully prepared in many counties and is to be applied to engineering practice, fire resistance of RPC200 needs a series of investigations urgently. The objectives of such investigations are to restrain explosive spalling and minimizing spalling probability, so as to ensure satisfactory fire resistance of RPC. It is expected that a research will be carried out on explosive spalling behavior, fracture properties, and micro-structure, to establish a mechanism as well as technical measures for improving fire resistance of RPC.

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20

TAKANO, Tomohiro, Takashi HORIGUCHI, and Noboru SAEKI. "FIRE-RESISTANCE OF HIGH STRENGTH FIBER REINFORCED CONCRETE." Doboku Gakkai Ronbunshuu E 63, no. 3 (2007): 424–36. http://dx.doi.org/10.2208/jsceje.63.424.

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21

Dwaikat, M. B., and V. K. R. Kodur. "Fire Induced Spalling in High Strength Concrete Beams." Fire Technology 46, no. 1 (April 17, 2009): 251–74. http://dx.doi.org/10.1007/s10694-009-0088-6.

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22

Li, Min, ChunXiang Qian, and Wei Sun. "Mechanical properties of high-strength concrete after fire." Cement and Concrete Research 34, no. 6 (June 2004): 1001–5. http://dx.doi.org/10.1016/j.cemconres.2003.11.007.

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23

Aljabbri, Noor Alhuda Sami, Mohammed Noori Hussein, and Ali Abdulmohsin Khamees. "Performance of Ultra High Strength Concrete Expose to High Rise Temperature." Annales de Chimie - Science des Matériaux 45, no. 4 (August 31, 2021): 351–59. http://dx.doi.org/10.18280/acsm.450411.

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Fire or high temperature is a serious issue to ultra-high-strength concrete (UHSC). Strength reduction of UHPCs may amount to as high as 80 percent after exposure to 800℃. A sum of four UHSC mixes was synthesized and evaluated in this study after getting exposed to extreme temperatures that reach 1000°C. Steel and polypropylene (PP) fibers were used in this experiment. A total of four mixes were made of UHSC without fibres as a control mix (UHSC-0), UHSC with 2% steel fibres (UHSC-S), UHSC with 2% PP fibres (UHSC-P) and UHSC with 1% steel fibres + 1% PP fibres (UHSC-SP). Workability, direct tensile strength, compressive strength, and splitting tensile strength were examined. Particularly, emphasis was devoted to explosive spalling since UHPCs are typically of compact structure and hence more prone to explosive spalling than other concretes. It was determined that the mixture UHSC-SP had high fire resistance. Following exposure to 1000℃, this mixture preserved a residual compressive strength of 36 MPa, splitting tensile strength of 1.62 MPa and direct tensile strength of 0.8 MPa. On the other hand, UHSC-P also had good fire resistance while UHSC-0 and UHSC-S experienced explosive spalling after heating above 200ᴼC. The incorporation of steel fibers in UHSC-S and UHSC-SP mixtures reveals higher tensile and compressive strength findings at different elevated temperatures as compared to UHSC-0 and UHSC-P. In addition, the result of direct tensile strength appears to be lower than splitting tensile strength at different raised temperatures.

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24

Patel, Vikas, Brijesh Singh, P. N. Ojha, and B. N. Mohapatra. "Effect on mechanical properties and stress strain characteristics of normal and high strength concrete at elevated temperature." Journal of Building Materials and Structures 7, no. 2 (October 12, 2020): 199–209. http://dx.doi.org/10.34118/jbms.v7i2.767.

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High strength concrete (HSC) has some disadvantages such as brittleness and poor resistance to fire. Fire exposure affects the concrete in way that the disintegration of concrete starts and a severe surface spalling occurs at very high temperatures. Therefore, the structural behaviour or response to the load will change after fire exposure and the structural members may not behave as they were designed. Further, the basics of flexural design depend on the stress- strain response of the concrete which is also affected upon fire exposure. Hence, this study is carried out to provide useful input to aid the provision of a fire resistance for structural behaviour of concrete by investigating the effects on mechanical properties of concrete after exposure to high temperatures up to 600°C and establishing a stress-strain relationship. The concrete cylinders of size 100 mm x 200 mm were exposed to the temperature of 2000C, 4000C and 6000C after which the residual compressive strength, split tensile strength and flexural strength were recorded. For stress strain characteristics, 100 × 200 mm cylinders with polypropylene fiber content of 0.5% by volume of concrete were subjected to temperature exposure of 6000C for durations of 1 hour. Curves for reduction factors of strength and stress strain characteristics after fire/elevated temperature exposure has been established. Just consideration of reduced strength for assessment after fire exposure will not serve the purpose as the change in load response and increased deformation capacity also needs to be addressed properly.

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25

Lyu, Xiao, Erfeng Du, and Ran Li. "Fire resistance of circulat steel tubes infilled with ultra-high strength concrete with external fire protection." Engineering review 39, no. 1 (2019): 71–80. http://dx.doi.org/10.30765/er.39.1.8.

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In this paper, a non-linear three-dimensional finite element model is presented in order to study the behaviour of axially loaded ultra-high strength concrete filled circular hollow tubular columns exposed to fire. Ultra-high strength concrete with compressive strength greater than 180 N/mm2 has been developed for concrete filled tubes for use in high–rise buildings. This paper studies the structural performance of fire protected ultra-high strength concrete filled tubular columns exposed to the standard ISO fire. The aim of this work is to understand and represent the behaviour of axially loaded ultra-high strength concrete filled circular hollow tubular columns in fire situations and to compare calculation results with experiment. The numerical analyses are carried out using a general finite element analysis package ABAQUS and the results are validated against the test results in terms of heat distribution and mechanical behavior. Comparison with the test results showed a reasonable agreement with finite element results in terms of temperature prediction and load displacement behavior during the fire.

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Bashynska, Olha, Yurii Otrosh, Oleksandr Holodnov, Andrey Tomashevskyi, and Galyna Venzhego. "Methodology for Calculating the Technical State of a Reinforced-Concrete Fragment in a Building Influenced by High Temperature." Materials Science Forum 1006 (August 2020): 166–72. http://dx.doi.org/10.4028/www.scientific.net/msf.1006.166.

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The purpose of research was to develop a methodology for testing the fire-resistant quality of a building fragment influenced by a real fire to substantiate the main calculation methodology provisions and determine the residual load-carrying ability. While testing, it was supposed to determine the technical state of reinforced-concrete structures after high-temperature exposure and further intensive extinguishment. High-temperature heating and further fire extinguishing with water leads to the surface layers’ destruction and weakening of concrete. Impact on the structures of the open air leads to destruction and delamination of weakened concrete with further exposing of reinforcement and its corrosion. The approach, implemented in LIRA-SAPR software package, makes possible to take into account the influence of changes in the temperature regime of operation on the stress-strain state of the structure. After determining the temperature fields, it is necessary to reduce the rigidity characteristics of materials and perform a calculation of strength. When using this approach in order to determine the total deformations of the structure, it is necessary to take into account the creep deformation.

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Farida, F. M., H. Hardjasaputra, A. Sofwan, and A. Surahman. "Compressive Strength Study based on Fly Ash Geopolymer Concrete at the age of 28 days under very High Temperature." Journal of Physics: Conference Series 2421, no. 1 (January 1, 2023): 012046. http://dx.doi.org/10.1088/1742-6596/2421/1/012046.

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Abstract Due to creeping process at the burning material, material’s elastic modulus and yield strength will decrease.Three fire protection system are exist in handling the fire problem: active fire protection, passive fire protection, and safety management. In correlation with material problem due to fire, passive fire protection is a strategy to counter it. This paper presents the results of fire protection by using Suralaya fly ash geopolymer concrete. Three molaritas of geopolymer concrete mixture design are 2M, 4M, and 6 M. Sodium Silicate (Na2SiO3) and Sodium Hydroxide (NaOH) are used as alkaline activator. The results of the experiment were analysed by compressive strength for the optimum values. This study found that the value of compressive strength of steam curing is higher than that of water curing, the value of geopolymer concrete compressive strength of 2M is higher than that of 4M, and the value of geopolymer concrete compressive strength of 6M is higher than that of 4M.

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28

Shi, Xin Lei, Yong Ding, Zhi Kun Yao, and Li Ping Zhou. "Experimental Research on Elastic Modulus and Compressive Strength of High-Strength Concrete after Fire." Advanced Materials Research 663 (February 2013): 144–48. http://dx.doi.org/10.4028/www.scientific.net/amr.663.144.

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Анотація:

The bottom surface of the bridge beam, which is made of C50 high-strength concrete, is heated to 800°C in fire-resistant experiment. Then the elastic modulus and strength of the concrete are measured by the rebound method and core sampling method, and the test results are used to validate the theoretical methods. The study shows that the strength and elastic modulus of concrete decrease with the increasing of temperature. The strength from the current theoretical analysis agrees well with that from the experiment. But for the elastic modulus, there is a great difference between the theoretical and experimental analysis. The strength of the concrete after fire gotten from the rebound method has a bigger error than that from the core sampling method, so that the core sampling method should be used in preference.

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Solikin, Mochamad. "Compressive Strength Development of High Strength High Volume Fly Ash Concrete by Using Local Material." Materials Science Forum 872 (September 2016): 271–75. http://dx.doi.org/10.4028/www.scientific.net/msf.872.271.

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This paper presents a research to produce high strength concrete incorporated with fly ash as cement replacement up to 50% (high volume fly ash concrete) by using local material. The research is conducted by testing the strength development of high volume fly ash concrete at the age of 14 days, 28 days and 56 days. As a control mix, the compressive strength of Ordinary Portland Cement (OPC) concrete without fly ash is used. Both concrete mixtures use low w/c. consequently, they lead to the use of 1 % superplasticizer to reach sufficient workability in the process of casting. The specimens are concrete cubes with the dimension of 15 cm x15 cm x 15 cm. The totals of 24 cubes of HVFA concrete and OPC concrete are used as specimens of testing. The compressive strength design of concrete is 45 MPa and the slump design is ± 10 cm. The result shows that the compressive strengths of OPC concrete at the age of 14 days, 28 days, and 56 days are 38 MPa, 40 MPa, and 42 MPa. Whereas the compressive strength of HVFA concrete in the same age of immersing sequence are 29 MPa, 39 MPa, and 42 MPa. The result indicates that HVFA concrete can reach the similar compressive strength as that of normal concrete especially at the age of 56 days by deploying low water cement ratio.

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30

Won, Jong-Pil, Seok-Won Choi, Chan-Gi Park, and Chang-Il Jang. "High Strength Polymer-Modified Repair Cementitious Composite for Fire Protection." Polymers and Polymer Composites 15, no. 5 (July 2007): 379–88. http://dx.doi.org/10.1177/096739110701500505.

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The purpose of this study was to evaluate the mechanical performance and fire resistance of a high strength polymer-modified cementitious composite, to test its ability to repair concrete tunnel structures that are in danger of collapse due to cracks or deterioration. In particular, because existing repair materials are not fire-resistant and commercial fire-resistant materials have low strength, this study was aimed at increasing the water tightness and strength of a repair material and also making it resistant to fire. In addition, this study evaluated changes in internal temperature depending on the cover thickness of repair materials to determine the optimal cover thickness at which a high strength polymer-modified cementitious composite could protect existing concrete tunnel structures from fire. Results indicated that the high strength polymer-modified cementitious composite had superior strength and water tightness than commercial fire-resistant materials and it also provided good fire resistance. The high strength polymer-modified cementitious composite required to be applied in an optimal layer thickness of at least 40 mm to protect existing structures from fire.

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31

Britez, C., P. Castro-Borges, A. Berto, and P. Helene. "Experimental evaluation of colored HSC column in fire conditions." Revista ALCONPAT 3, no. 1 (January 30, 2013): 39–54. http://dx.doi.org/10.21041/ra.v3i1.42.

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ABSTRACTIn recent times it has been common to associate high-strength concrete with a greater susceptibility to explosive type spalling, when subjected to high temperatures. In part, this doubt is a result of some experimental programs that are carried out on small unreinforced concrete samples (specimens), which could substantially influence the structural concrete behavior in fire conditions. This paper presents an experimental program, carried out in Brazil on a high strength colored reinforced concrete column (HSCC), eight years-old, fc,8years = 140MPa, basalt coarse aggregate, cross section of 700mm x 700mm, tested under no load and with three faces exposed to standard fire curve ISO 834 for 180min (3h). The results demonstrated, in this case, that HSCC maintained integrity under experimental fire and that the iron oxide pigments can work as an excellent natural thermometer, contributing to the evaluation of the structure post-fire simulation.Keywords: High-strength concrete; fire resistance; colored concrete; column in fire; iron oxide pigment. RESUMENHa sido común asociar el concreto de alta resistencia con una mayor susceptibilidad al desprendimiento por explosión (spalling) cuando se le somete a altas temperaturas. Esta duda se debe en parte a los resultados de algunos programas experimentales que se han llevado a cabo en pequeñas probetas de concreto simple sin refuerzo, lo que puede influir sustancialmente en el comportamiento del concreto en situación de incendio. Este artículo presenta un programa experimental en Brasil donde un pilar de concreto armado colorido de alta resistencia (HCAR), con ocho años de edad, fc,8años = 140MPa, árido grueso basáltico, sección cuadrada de 700mm x 700mm, fue ensayado sin carga y con tres lados expuestos al fuego (curva ISO 834) durante 180min (3h). Los resultados demostraron en este caso que el HCAR se mantuvo íntegro y que los pigmentos de óxido de hierro pueden trabajar como excelente termómetro natural, contribuyendo en la evaluación de la estructura después de la simulación de incendio.Palabras Clave: Concreto de alta resistencia; resistencia al fuego; concreto colorido; pilar sometido al fuego; pigmento de óxido de hierro.

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32

Hooton, RD, M. Sonebi, and KH Khayat. "Testing Abrasion Resistance of High-Strength Concrete." Cement, Concrete and Aggregates 23, no. 1 (2001): 34. http://dx.doi.org/10.1520/cca10523j.

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33

Davidyuk, Artem, and Igor Rumyantsev. "Quality control of high-performance concrete in high-rise construction during operation." MATEC Web of Conferences 170 (2018): 01035. http://dx.doi.org/10.1051/matecconf/201817001035.

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Анотація:

With onset of the XXI century, the demand for construction of high-rise buildings with the load-bearing framework made of high-performance cast-in-situ concrete has increased many-fold in the construction sector. Specific features of the high-performance concrete of bearing structures in the situation of real operation of high-rise buildings are continuously studied by scientists and specialists all over the world, and regulatory and methodological documents are being complemented and adjusted. High-performance concretes and structures made of them possess some specific features that should be taken into account in quality control. The methods of concrete inspection and concrete strength evaluation described in GOST 18105 “Concretes. Guidelines on Testing and Evaluation of Strength” and GOST 22690 “Concretes. Evaluation of Strength by Mechanic Non-Destructive Test Methods” were written when precast reinforced concrete was predominantly used in the construction sector and were limited to the functions of intra-factory quality control of reinforced concrete products. At present, instruments for non-destructive testing using indirect methods are usually calibrated with the help of local destructions, as a rule, a pull out or rib shear test. The said methods are in fact indirect since they indicate the force of destruction of the surface layer of a structure.

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34

Kim, Heung Youl, Hyung Jun Kim, Kyung Hoon Park, Bum Youn Cho, and Jae Sung Lee. "Fire Resistance Performance of High-Strength Concrete Columns Reinforced with Pre-Stressed Wire Ropes." Applied Mechanics and Materials 470 (December 2013): 880–83. http://dx.doi.org/10.4028/www.scientific.net/amm.470.880.

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In this study, the fire resistance performance of high-strength concrete columns was evaluated to see the influence of lateral confinement reinforcement with wire ropes for improving ductility, fire resistance reinforcement with fiber cocktail and load ratio. For this, loaded fire test was conducted under ISO834 standard fire condition. The axial ductility of the 60MPa high-strength concrete column reinforced with pre-stressed wire ropes was improved and its fire resistance performance was also improved by 23% compared with its counterpart without wire ropes. The appropriate load for the 60MPa concrete column reinforced with wire ropes was found to be 70% of design load. The fire resistance performance of the 100MPa high-strength concrete column reinforced with pre-stressed wire ropes and fiber-cocktail was improved as much as 4 times compared with that reinforced with tie bars only. The appropriate load for the 100MPa columns was found to be less than 70% of design load in order for the columns to secure required fire resistance performance.

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35

Jovan Perdhana, Bambang Wedyantadji, and Vega Aditama. "PENGGUNAAN LIMBAH ABU KAYU HALABAN SEBAGAI BAHAN TAMBAHAN SEBAGIAN SEMEN PADA CAMPURAN BETON." SONDIR 6, no. 1 (April 18, 2022): 46–55. http://dx.doi.org/10.36040/sondir.v6i1.5173.

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Halaban wood ash is the result of chemical changes from the process of burning Halaban wood with a fire of about ±1000ºC and it takes about 150 minutes to turn the wood lump cells into ash. Halaban wood ash contains silica which is a good aggregate binder and is quite high, so it has pozzolanic properties. This study aims to determine the effect of adding ash from burning halaban wood on the mechanical properties of concrete and also knowing the optimum percentage of halaban wood ash from 0%, 5%, 10%, 15% in terms of compressive strength of concrete, split tensile strength of concrete and flexural tensile strength. concrete. The method used in this study is the DOE (Design Of Experiment) method using a cylindrical specimen with a diameter of 15 cm and a height of 30 cm for testing the compressive strength of concrete, beams with a size of 15 cm x 15 cm x 62 cm for testing the flexural strength. The test object was made with 4 variations of the composition of Halaban Wood Ash as a concrete testing material, namely 0%, 5%, 10%, 15% by weight of cement. Testing of the specimens was carried out at the age of 28 days. The number of test objects as many as 64 pieces. Based on the research conducted, it is known that there is no effect in increasing the strength of concrete with the addition of halaban wood ash on the mechanical properties of concrete. This is indicated by the decrease in the results of testing the compressive strength, split tensile strength, and flexural tensile strength of normal concrete with a mixture of halaban wood ash. And the absence of the optimum percentage of Halaban wood ash from 5%, 10%, 15% in terms of the compressive strength of concrete, split tensile strength of concrete and flexural tensile strength of concrete.

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36

Ou, Man Li, Wei Jun Cao, and Long Min Jiang. "Study on the Mechanical Property of Concrete Materials under High Temperature (Fire)." Applied Mechanics and Materials 166-169 (May 2012): 3018–22. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.3018.

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Анотація:

The performance of concrete materials under high temperature is more complex than that under room temperature. This paper, by analyzing the mechanical property of concrete materials under high temperature(fire), probes into the changing law of the concrete materials' compressive strength under different temperatures (16 °C-800 °C) and different static placing time and makes a comparison on the concrete materials' strength between natural cooling and water cooling; illustrates the relationships of concrete materials' compressive strength and temperature, holding time and cooling and other factors under high temperature(fire).

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37

Aulia, Teuku Budi, Muttaqin Muttaqin, Mochammad Afifuddin, and Zahra Amalia. "Analysis of Post-Combustion High-Strength Concrete Compressive Strength Using Polypropylene Fibers." MEDIA KOMUNIKASI TEKNIK SIPIL 26, no. 1 (July 30, 2020): 118–27. http://dx.doi.org/10.14710/mkts.v26i1.28262.

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High-strength concrete is vulnerable to high temperatures due to its high density. The use of polypropylene fibers could prevent structure explosion by forming canals due to melted fibers during fire, thus release its thermal stress. This study aims to determine the effect of polypropylene fibers on compressive strength of high-strength concrete after combustion at 400ºC for five hours. High-strength concrete was made by w/c-ratio 0.3 with cement amount 550 kg/m3 and added with silica fume 8% and superplasticizer 4% by cement weight. The variations of polypropylene fibers were 0%, 0.2% and 0.4% of concrete volume. The compression test was carried out on standard cylinders Ø15/30 cm of combustion and without combustion specimens at 7 and 28 days. The results showed that compressive strength of high-strength concretes without using polypropylene fibers decreased in post-combustion compared with specimens without combustion, i.e., 0.81% at 7 days and 23.42% at 28 days. Conversely, the use of polypropylene fibers can increase post-combustion compressive strength with a maximum value resulted in adding 0.2% which are 25.52% and 10.44% at 7 and 28 days respectively. It can be concluded that the use of polypropylene fibers is effective to prevent reduction of high-strength concrete compressive strength that are burned at high temperatures.

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38

Sovová, Kateřina, Karel Mikulica, Adam Hubáček, and Karel Dvořák. "Behavior of High Strength Concrete at High Temperatures." Solid State Phenomena 276 (June 2018): 259–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.276.259.

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Concrete is considered as a non-combustible building material. However, at High-Performance Concrete (HPC) is due to its dense structure more likely to occur in explosive spalling. This results in lost of load bearing capacity function of concrete. This paper deals with design, production and testing of the cement-based concrete with the use of different fibers (polypropylene fibers and cellulose fibers). It also assesses the influence of high temperature on strength, visual changes of specimens, changes of surface and degradation of testing specimens due to heat loads according to normative heat curve and also according to hydrocarbon curve.

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39

Zende, Aijaz, A. Kulkarni, and Aslam Hutagi. "Behavior of Reinforced Concrete Subjected to High Temperatures-A Review." Journal of Structural Fire Engineering 4, no. 4 (December 1, 2013): 281–95. http://dx.doi.org/10.1260/2040-2317.4.4.281.

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This paper reviews the research carried on effects of fire on the mechanical and thermal properties on concrete. Fire in the structure causes higher temperature at the concrete surface, which causes a reduction in compressive strength, modulus of elasticity of concrete. Though concrete is a poorer conductor than steel, sustained high temperature at the surface leads to progressive heating of the inner layers of concrete. This leads to exposing reinforcing bars to higher temperature; which causes a reduction in the yield stress, ductility and tensile strength of steel. This paper also focuses on the concrete cover, the reinforcement bars in a concrete structure are protected against fire only by the concrete cover layer thus higher is the cover more is the resistance and vice a versa. Effects of temperature on the thermal conductivity of concrete is also discussed in detail.

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40

Chen, Bo, Yue Bo Cai, Jian Tong Ding, and Yao Jian. "Crack Resistance Evaluating of HSC Based on Thermal Stress Testing." Advanced Materials Research 168-170 (December 2010): 716–20. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.716.

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In order to evaluate the crack resistance of high strength fly ash concrete, concretes with different contents of silica fume and fly ash were compared with same strength grade by adjusting water to binder ratio. Compared with the concrete with 5% silica fume plus 35% fly ash，concrete with 40% fly ash has same mechanical properties and tensile strain as well as lower drying shrinkage. Complex crack resistance of high strength fly ash concretes were evaluated by Temperature Stress Testing Machine (TSTM). The results show that fly ash concretes have outstanding crack resistance because of higher allowable temperature differential and lower cracking temperature.

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41

Vincent, Thomas, and Togay Ozbakkloglu. "An Experimental Study on the Compressive Behavior of CFRP-Confined High- and Ultra High-Strength Concrete." Advanced Materials Research 671-674 (March 2013): 1860–64. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.1860.

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It is well established that external confinement of concrete with fiber reinforced polymer (FRP) sheets results in significant improvements on the axial compressive behavior of concrete. This understanding has led to a large number of experimental studies being conducted over the last two decades. However, the majority of these studies have focused on normal strength concretes (NSC) with compressive strengths lower than 55 MPa, and studies on higher strength concretes have been very limited. This paper presents the results of an experimental study on the compressive behavior of FRP confined high- and ultra high-strength concrete (HSC and UHSC) with average compressive strengths of 65 and 100 MPa. A total of 29 specimens were tested under axial compression to investigate the influence of key parameters such as concrete strength and method of confinement. All specimens were cylindrical, confined with carbon FRP and were 305 mm in height and 152 mm in diameter. Results obtained from the laboratory testing were graphically presented in the form of axial stress-strain relationships and key experimental outcomes are discussed. The results of this experimental study indicate that above a certain confinement threshold, FRP-confined HSC and UHSC exhibit highly ductile behavior. The results also indicate that FRP-wrapped specimens perform similar to concrete-filled FRP tube (CFFT) specimens at ultimate condition, however notable differences are evident at the transition region when comparing stress-strain curves.

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42

Yu, Shui Jun, Yu Long Wang, Ben Jie Duan, Jun Wei Zhou, Fei Yang, Xu Ge Wang, and Dong Lin Liang. "Fireproof Performance of Foam Concrete Insulation Board." Advanced Materials Research 250-253 (May 2011): 474–79. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.474.

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Foam concrete is used in building energy-saving insulation works, to study its fire performance is very important for further enhancing the fire performance of buildings. Under simulated fire conditions, by determining the compressive strength of foam concrete at different densities, different calcination time and different water content, this experiment studies the effect of these conditions on the fire performance of foam concrete. The results show that in case of fire, the compressive strength loss rate of foam concrete increases with the decreasing of density; to calcine the foam concrete standard specimens whose density are 300kg/m3 and 800kg/m3, their strength loss rates are 66.3% and 25.5%, the compressive strength of foam concrete in the same density increases with the calcination time decreasing, water content has different effects on different densities of foam concrete in the fire security. The foam concrete is non-flammable, but its compressive strength decreases due to the fire of combustible materials and high-temperature calcination.

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43

Kurtoglu, Ahmet, and Derya Bakbak. "New model for compressive strength loss of lightweight concrete exposed to elevated temperatures." Thermal Science 23, Suppl. 1 (2019): 285–93. http://dx.doi.org/10.2298/tsci181030042k.

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This study proposes a new model for the residual compressive strength of structural lightweight concrete after exposure to elevated temperatures up to 1000?C. For this purpose, a database of residual compressive strengths of fire exposed lightweight concrete was compiled from the literature. Database consisted a total number of 289 data points, used for generating training and testing datasets. Symbolic regression was carried out to generate formulations by accounting for various input parameters such as heating rate, cooling regime, target temperature, water content, aggregate type, and aggregate content. Afterwards, predictions of proposed formulation is compared to experimental results. Statistical evaluations verify that the prediction performance of proposed model is quite high.

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44

JERÔNIMO, V. A., A. C. PICCININI, B. V. SILVA, D. S. S. GODINHO, A. M. BERNARDIN, and A. VARGAS. "Influence of concrete admixture on the bond strength of reinforced concrete submitted to high temperature." Revista IBRACON de Estruturas e Materiais 13, no. 2 (April 2020): 212–21. http://dx.doi.org/10.1590/s1983-41952020000200003.

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Abstract High temperatures can affect the macro and micro structural properties of reinforced concrete. This work aimed to analyze the bond strength behavior after high temperature exposure of two classes of concrete, the conventional 30 MPa and the high compressive strength 65 MPa concrete. The pullout test proposed by RILEM CEB / FIP RC6 (1983) was used for the evaluation of the compressive strength and modulus of elasticity. The influence of temperature on the physical-mechanical properties of concrete samples under a simulated fire situation was also studied for the evaluation of the resistant capacity in a post-fire situation. In addition to the analysis at 28 days, samples of the 30 MPa (group I) and 65 MPa (group II) classes were also investigated at 90 days exposed to room (23 °C), 400 °C and 800 °C temperatures. The bond strength curve was similar to that of compressive strength, where, at 400 °C, there was no statistical difference regarding room temperature and, at 800 °C, there was significant loss of strength in all cases. At 90 days age there was a loss of bond strength of 51 and 40 % for groups I and II, respectively. At 800°C the reductions were above 50 % in compressive strength and above 80 % in the modulus of elasticity, for both groups. These results show the structural impairment under high temperature. Comparing the test 28 and 90 days ages, there was no significant influence of age on the bond and compressive strength of the concretes.

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45

Wei, Ya, Francis T. K. Au, Jing Li, and Neil C. M. Tsang. "Experimental and numerical investigation of post-tensioned concrete flat slabs in fire." Journal of Structural Fire Engineering 7, no. 1 (March 14, 2016): 2–18. http://dx.doi.org/10.1108/jsfe-03-2016-001.

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Анотація:

Purpose This paper aims to understand the structural fire performance of two-way post-tensioned flat slabs, particularly their deformations and load-carrying mechanisms in fire, and to explore the behaviour of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons in fire. Design/methodology/approach Four tests of post-tensioned high-strength self-compacting concrete flat slabs were conducted under fire conditions. Numerical modelling using the commercial package ABAQUS was conducted to help interpret the test results. Findings Two of the specimens with lower moisture contents demonstrated excellent fire resistance performance, while the others with slightly higher moisture contents experienced severe concrete spalling. Originality/value The test results were discussed in respect of thermal profiles, deflections, crack patterns and concrete spalling. The performance of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons under fire conditions was better understood.

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46

Wedatalla, Afaf M. O., Yanmin Jia, and Abubaker A. M. Ahmed. "Curing Effects on High-Strength Concrete Properties." Advances in Civil Engineering 2019 (March 6, 2019): 1–14. http://dx.doi.org/10.1155/2019/1683292.

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Анотація:

This study was conducted to investigate the impact of hot and dry environments under different curing conditions on the properties of high-strength concrete. The concrete samples were prepared at a room temperature of 20°C and cured under different curing conditions. Some specimens underwent standard curing from 24 h after casting until the day of testing. Some specimens underwent steam curing in a dry oven at 30°C and 50°C after casting until the day of testing. Other specimens were cured for 3, 7, 21, and 28 days in water and then placed in a dry oven at 30°C and 50°C and tested at the age of 28 days, except for the specimens that were cured for 28 days, which were tested at the age of 31 days, to study the effect of curing period on the strength of concrete exposed to dry and hot environments after moist curing. The effects of hot and dry environments on high-strength concrete with different water/binder ratios (0.30, 0.35, and 0.40), using (30%) fly ash for all mixes, and (0%, 5%, and 10%) silica fume with the binder (450, 480, and 520 kg), respectively, were separately investigated, and the effects of curing under different conditions were evaluated by measuring the compressive strength, flexural strength, microhardness, and chloride diffusion and by assessing the concretes’ microstructure. The relationships between these properties were presented. A good agreement was noted between the concrete compressive strength and concrete properties at different temperatures, curing periods, and curing methods.

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47

Razak, Siti Nooriza Abd, Nasir Shafiq, Laurent Guillaumat, Syed Ahmad Farhan, and Vicky Kumar Lohana. "Fire-Exposed Fly-Ash-Based Geopolymer Concrete: Effects of Burning Temperature on Mechanical and Microstructural Properties." Materials 15, no. 5 (March 3, 2022): 1884. http://dx.doi.org/10.3390/ma15051884.

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Анотація:

Geopolymer concrete possesses superior fire resistance compared to ordinary Portland cement (OPC)-based concrete; however, there are concerns regarding its vulnerability when exposed to real fire events. In the present study, the fire resistance of fly-ash-based geopolymer concrete was evaluated relative to that of OPC-based concrete. Concrete specimens of standard strength grades of 20, 40, and 60 MPa were exposed to fire at 500 and 1200 °C for 2 h to simulate real fire events. Visual observation was performed, mass loss and residual compressive strength were measured, and scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted. OPC-based concrete suffered major cracks accompanied with spalling for the high-strength specimen, while geopolymer concrete experienced minor cracks with no spalling. Mass losses of the geopolymer concrete—of 1.69% and 4%, after the exposure to fire at 500 and 1200 °C, respectively—were lower than those of the OPC-based concrete. More than 50% of the residual compressive strength for low- and medium-strength geopolymer concrete, after the exposure to fire at 1200 °C, was maintained. After the exposure to fire at 500 °C, the residual compressive strength of the geopolymer concrete increased from 13 to 45%, while the OPC-based concrete was not able to sustain its compressive strength. SEM images showed that the matrix of the geopolymer concrete, after the exposure to fire, was denser than that of the OPC-based concrete, while the FTIR spectra of the geopolymer concrete showed a minor shift in wavelength. Hence, our findings indicate that fly-ash-based geopolymer concrete has an excellent fire resistance as compared to OPC-based concrete.

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48

Kodur, V. K. R., and R. McGrath. "Effect of silica fume and lateral confinement on fire endurance of high strength concrete columns." Canadian Journal of Civil Engineering 33, no. 1 (January 1, 2006): 93–102. http://dx.doi.org/10.1139/l05-089.

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Анотація:

Fire represents one of the most severe environmental conditions, and therefore should be properly accounted for in the design of structural members. The increased use of high strength concrete (HSC) in buildings has raised concerns regarding the behaviour of such concrete in fire. In particular, spalling at elevated temperatures, as identified in studies by a number of laboratories, is a main concern. In this paper, results from experimental studies on the fire resistance of HSC columns are presented. A comparison is made of the fire resistance performance of HSC columns with and without silica fume and with different confinement configurations. The effect of silica fume and the effect of confinement on the fire performance of HSC columns will be discussed. The results show that the fire endurance of HSC columns with higher silica fume content is lower and the reduced tie spacing and the provision of cross-ties are beneficial in minimizing the spalling in HSC.Key words: fire resistance, high strength concrete, reinforced concrete columns, spalling.

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49

Bickley, J. A., J. Ryell, C. Rogers, and R. D. Hooton. "Some characteristics of high-strength structural concrete." Canadian Journal of Civil Engineering 18, no. 5 (October 1, 1991): 885–89. http://dx.doi.org/10.1139/l91-107.

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The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of some silica fume concretes after long exposure to low humidity, the determinations being made on standard test cylinders. Tests were, therefore, made at ages of 1 year and 2 years on specimens drilled from columns in the structure. This technical note gives details of the laboratory examination and testing of these specimens. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticizers.

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50

Ali, F., A. Nadjai, P. Glackin, Gordon Silcock, and A. Abu-tair. "Structural Performance Of High Strength Concrete Columns In Fire." Fire Safety Science 7 (2003): 1001–12. http://dx.doi.org/10.3801/iafss.fss.7-1001.

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