scholarly journals Mechanical properties of various concrete after high temperature exposure Mechanical property of various types of concrete after high temperature exposure is investigated. Considering compressive strength requirement for a vertical element in high rise building, concrete specimens with various design strengths of 35, 80, 100, and 150 MPa were tested. Particularly, the influence of incorporated steel fiber on fire resistance is of interest in this study. Experimental results show that the fire resistance depends on the design strength and steel fiber content. Normal strength concrete (NSC) of a design strength of 35 MPa or high performance concrete (HPC) of 80-100 MPa does not spall when exposed to 100-400 °C of temperature. However, an explosive spalling occurs at 300 °C when the HPCs contain 1 vol.% of steel fiber. Ultra-high performance concrete (UHPC) of a design strength of 150 MPa and 1.5 vol.% of steel fiber also shows dramatic spalling at 300 °C. The experimental results found in this study can contribute to a better understanding of the behaviors of HPC and UHPC under fire and the role of steel fiber on the fire resistance.

2017 ◽  
Keyword(s):  
High Temperature ◽  
Fire Resistance ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Experimental Results ◽  
Explosive Spalling ◽  
Design Strength ◽  
High Temperature Exposure ◽  
Temperature Exposure

Behavior of High Performance Steel-Fiber Concrete Exposed to High Temperature in Terms of Spalling and Permeability

2014 ◽  
Vol 629-630 ◽  
pp. 252-258 ◽  
Author(s):  
Gai Fei Peng ◽  
Xu Jie Duan ◽  
Xue Chao Yang ◽  
Ting Yu Hao
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Plain Concrete ◽  
Thermal Exposure ◽  
Explosive Spalling ◽  
Fiber Concrete ◽  
Steel Fiber Concrete ◽  
High Performance Steel

An experimental investigation was conducted on behavior of high performance steel-fiber concrete subjected to high temperature, in terms of explosive spalling and permeability. A series of concretes incorporated steel fiber at various dosages were prepared, and further processed to have a series of moisture contents. Explosive spalling tests were conducted on control plain concrete and steel fiber concrete. After explosive spalling tests, each of the specimens that didn’t encounter spalling was sawn into two pieces. Crack observations and permeability tests were conducted on the sawn surfaces. The results prove that steel fiber is efficient to avoid spalling concrete under high temperature. The permeability increases significantly after thermal exposure, while it also exhibits an ascending trend with the increase of moisture content. Therefore it is concluded that steel fiber can play a positive effect on explosive spalling of high performance concrete under high temperature, as well as on permeability after thermal exposure.

The Influence on High-Temperature Mechanical Properties of Hybrid-Fiber-Reinforced High-Performance Concrete and Microscopic Analysis

2012 ◽  
Vol 226-228 ◽  
pp. 1709-1713
Author(s):  
Lan Yan ◽  
Y.M. Xing ◽  
Ji Jun Li
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Transition Zone ◽  
High Performance ◽  
Room Temperature ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Interfacial Transition Zone ◽  
Hybrid Fiber ◽  
High Temperature Mechanical Properties

This paper investigated the high temperature mechanical properties of the hybrid fiber reinforced high performance concrete (HFHPC) and normal concrete (NC) .After being subjected to different elevated heating temperatures, two kinds of concretes have been tested for the compressive strength, splitting tensile strength and flexural strength of test specimen at room temperature and 200 °C,400 °C,600 °C,800 °C.Microstructure changes of concrete were also observed by using Scanning Electron Microscopy (SEM) after high temperature. The results show that the hybrid fiber can significantly increase mechanical properties of the concrete at room temperature and high temperature. SEM and XRD analysis shows that there is a permeable diffusion layer in the steel fiber surface because of solid state reaction in the Interfacial Transition Zone of steel fiber and concrete. This permeable diffusion layer is white, bright, serrated and mainly consist of FeSi2 and the complex hydrated calcium silicate. The compounds of this layer change the Interfacial Transition Zone structure, enhance bonding capacity of the steel fiber and matrix, and increase the high temperature mechanical properties of concrete.

Fire-Damage or Freeze-Thaw of Strengthening Concrete Using Ultra High Performance Concrete

2009 ◽  
Vol 79-82 ◽  
pp. 2047-2050 ◽  
Author(s):  
Min Gin Lee ◽  
Yi Shuo Huang
Keyword(s):  
High Temperature ◽  
High Performance ◽  
High Performance Concrete ◽  
Fire Damage ◽  
Ultra High Performance Concrete ◽  
Freeze Thaw ◽  
Concrete Members ◽  
Repair Materials ◽  
Environmental Durability ◽  
Temperature Exposure

There are some reinforced concrete structures exposed to severe environmental conditions might require maintenance or strengthening. Many of these severe circumstances are the result of extreme climate conditions such as low temperature, freeze–thaw action, fire attack, and exposure to deicing salts. Because of this, the environmental durability of both the repair materials and methods used in rehabilitation applications are of utmost importance. A small fire can reach 250°C, while a common blaze can easily produce temperatures of around 800°C. In major conflagrations the temperature can even reach 1100°C. At this level, the heat affects most materials, provoking the spontaneous combustion of some of them and affecting the resistance of others. However, very little research has been performed in evaluating the environmental durability of strengthening materials for concrete members. Very little work has been done on the effects of freeze–thaw cycling on bonding and repair materials. In this study, ultra high performance concrete (UHPC) was used to investigate the effect of strengthening concrete members by fire-damage test or freeze-thaw test. The results show that the mechanical properties of UHPC possess high strength, toughness, and freeze-thaw resistance. The CFRP (carbon fiber reinforced plates) wrapping specimens exposed at 300 °C showed totally failure with the deterioration of the adhesive. The UHPC with bonding 10 mm thickness specimens exposed at 400 °C and duration of 1 hour still in good shape. The UHPC with 1-cm or 2-cm thickness on strengthening concrete members could be obtained specific retrofit effects. The performance of UHPC specimens is better than those of CFRP wrapping specimens during high temperature exposure. The results of slant shear tests show that the bond strength of PC/PC, UHPC/PC and UHPC/UHPC decreased significantly after 600 freeze–thaw cycles or high temperature exposure.

The Mechanism of Explosive Spalling and Measures to Resistant Spalling of Concrete Exposed to High Temperature by Incorporating Fibers: A Review

2010 ◽  
Vol 168-170 ◽  
pp. 773-777 ◽  
Author(s):  
Juan Yang ◽  
Gai Fei Peng
Keyword(s):  
High Strength Concrete ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Polypropylene Fiber ◽  
High Strength ◽  
Hybrid Fiber ◽  
Explosive Spalling ◽  
Preliminary Study ◽  
Experimental Researches

Many experimental researches have been conducted on explosive spalling performance of concrete of high-strength / high performance concrete (HSC/HPC). This paper summarizes two main explosive spalling mechanisms (Vapor pressure build-up mechanism and Thermal stress mechanism) of concrete at elevated temperature, and also presents the measures to resistant the explosive spalling, i.e. by incorporating fibers (polypropylene fiber(PPF), steel fiber(SF) and hybrid fiber of the first two). Finally, the further studies of both the mechanism and the measures are proposed. Also, the preliminary study of ultra high-strength concrete (UHSC) on fire-resistance are mentioned.

scholarly journals Effect of Exposure to High Temperature on the Mechanical Properties of SIFRCCs

2020 ◽  
Vol 10 (6) ◽  
pp. 2142
Author(s):  
Seungwon Kim ◽  
Topendra Oli ◽  
Cheolwoo Park
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Flexural Strength ◽  
Fire Resistance ◽  
Fiber Reinforced ◽  
High Temperature Exposure ◽  
Organic Fiber ◽  
Compressive And Flexural Strengths ◽  
Temperature Exposure ◽  
Concrete Model

Many researchers have studied explosion prevention and fire resistance of high-strength concrete mixed with organic fiber and steel fibers. The fire resistance of high-performance fiber reinforced cement composites is desirable in terms of physical and mechanical properties. However, the use of a polymer as an alternative to organic fiber has not been clearly studied. In this study, a slurry infiltration method was used to obtain slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs) specimens. Powder polymer was used instead of organic fibers during mixing of the slurry. The compressive and flexural strengths of the specimens after 1 hr of high temperature exposure according to the KS F 2257 (ISO 834) standard fire-temperature curve were measured. The addition of the polymer before and after high temperature (about 945 °C) exposure affected the strength of the SIFRCCs. The compressive and flexural strengths were decreased after exposure to high temperature in comparison with SIFRCCs without polymer because polymer create capillary pores due to melting and burning when exposure to high temperature. This minimizes the vapor pressure inside the concrete model and reduces the failure of the concrete model. The experimental results showed that the flexural strength at a high temperature for 1.0 % polymer content was the highest at 53.8 MPa. The flexural strength was reduced by 40~50% when compared to the flexural strength before high temperature exposure and comparing to SIFRCCs without polymer, the compressive strength in 1.5% polymer is lower, owing to voids that are created in the SIFRCCs after exposure to a high temperature.

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