scholarly journals Mechanical Properties of Concrete with Steel and Polypropylene Fibres at Elevated Temperatures

Fibers ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 9 ◽  
Author(s):  
Josipa Bošnjak ◽  
Akanshu Sharma ◽  
Kevin Grauf
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Elevated Temperature ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
High Strength ◽  
Fibre Reinforced Concrete ◽  
Explosive Spalling ◽  
Steel Fibres ◽  
Strength Concrete

Addition of steel fibres to concrete is known to have a significant positive influence on the mechanical properties of concrete. Micro polypropylene (PP) fibres are added to concrete to improve its performance under thermal loads such as in case of fire by preventing the phenomena of explosive spalling. An optimum mixture of steel and micro PP fibres added to concrete may be utilized to enhance both the mechanical and thermal behaviour of concrete. In this work, systematic investigations were carried out to study the influence of elevated temperature on the mechanical properties and physical properties of high strength concrete without and with fibres. Three different mixtures for high strength concrete were used, namely normal concrete without fibres, Steel fibre reinforced concrete and Hybrid fibre reinforced concrete having a blend of hooked end steel fibres and micro PP fibres. The specimens were tested in ambient conditions as well as after exposure to a pre-defined elevated temperature and cooling down to room temperature. For all investigated concrete mixtures the thermal degradation of following properties were investigated: compressive strength, tensile splitting strength, bending strength, fracture energy and static modulus of elasticity. This paper summarizes the findings of the tests performed.

Mechanical Properties of HPC and Numerical Simulation of Mine Shaft under 3D Load

2015 ◽  
Vol 777 ◽  
pp. 48-51
Author(s):  
Hui Cao ◽  
Lin Lin Jiang
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
Effective Strain ◽  
Earth Pressure ◽  
High Strength ◽  
Wall Structure ◽  
Concrete Wall ◽  
Mine Shaft ◽  
Strength Concrete

The mechanical properties of high-strength concrete was studied in the laboratory, and obtained a high strength concrete uniaxial compressive strength changes with curing period, found that low temperature curing C100 Poisson's ratio of concrete is 0.24, and elastic modulus reached about 52.5GPa. The test results are applied to the numerical calculation, established a separate type reinforced concrete wall, and the multiaxial loading the stress state is simulated, the research shows that it is applied to C100 reinforced concrete shaft lining under its own gravity and the surrounding soil earth pressure, the maximum effective stress are respectively 25MPa , and effective strain is 4E-4mm, structure of shaft wall failure caused by shear wall structure. Under the three state of compression, the strength of concrete is improved.

Effect of different fiber types on the mechanical properties of normal and high strength concrete at elevated temperatures

2021 ◽  
Vol 12 (1) ◽  
pp. 30
Author(s):  
Mohamed Amin ◽  
Khaled Abu el-hassan
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
Polypropylene Fiber ◽  
High Strength ◽  
Fiber Types ◽  
Strength Concrete ◽  
Compressive And Flexural Strengths ◽  
Fiber Addition

The effects of the types of fibers on mechanical properties of normal and high strength concrete under high temperature, up to 700 °C, was investigated. Three different- type fiber; "Steel Fiber (SF), Glass Fiber (GF) and Polypropylene Fiber (PPF)" are added into the concretes in five different ratios (0, 0.50, 1.00, 1.50 and 2.0%)of the volume under the following temperatures; 22, 100, 400 and 700°C. The results indicate that all the different types of fibers researched contribute to both the compressive and flexural strengths of concrete under high temperature, however, it is also found that this contribution decreases with an increase in temperature. The flexural strengths and compressive strengths for NSC and HSC mixes at 28 days under high temperature decreases as the temperature increases especially up to 400°C. Also, the best compressive and flexural strengths performance under high temperature was also those of SF. The compressive strength of the concrete incorporating SF was reduced under high temperature only, while the mixes containing PPF and GF were reduced under high temperature or with fiber addition. The optimum fiber addition ratios of the mixes containing PPF and GF are between 0.5-1.0 percent by volume. And for SF, it is 1.5% by the volume.

Reliability Analysis of High-Strength Concrete Columns during a Fire

2014 ◽  
Vol 629-630 ◽  
pp. 273-278 ◽  
Author(s):  
Jian Zhuang Xiao ◽  
Qing Hai Xie ◽  
Yi Zhao Hou ◽  
Zhi Wei Li
Keyword(s):  
Reliability Analysis ◽  
Fire Resistance ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
Axial Loading ◽  
High Strength ◽  
Concrete Columns ◽  
Explosive Spalling ◽  
Strength Concrete ◽  
High Strength Concrete Columns

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.

scholarly journals ASSESSMENT OF MECHANICAL PROPERTIES OF HIGH STRENGTH CONCRETE (HSC) AFTER EXPOSURE TO HIGH TEMPERATURE

2018 ◽  
Vol 24 (2) ◽  
pp. 138-144 ◽  
Author(s):  
Tomasz DRZYMAŁA ◽  
Wioletta JACKIEWICZ-REK ◽  
Jerzy GAŁAJ ◽  
Ritoldas ŠUKYS
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Strength Concrete ◽  
High Performance Concrete ◽  
High Strength ◽  
Hardened Concrete ◽  
Explosive Spalling ◽  
Polypropylene Fibres ◽  
Strength Concrete ◽  
Temperature Conditions

There has been a tendency to design ever slender building construction using high strength concrete in recent years. Application of HSC is also growing in tunnel construction. One of the most important challenges is to control explosive spalling of concrete and the method recommended by Eurocode 2 (EN 1992-1-2:2008/NA:2010P) is addition of polypropylene fibres to the mix. The purpose of the research described in this paper was to evaluate the changes of mechanical properties of HSC exposed to the effect of high temperature. The tests were carried out on three types of high strength concrete: air-entrained concrete, polypropylene fibre-reinforced concrete and reference concrete having constant water/cement ratio. The properties of hardened concrete including compressive strength, tensile splitting strength, flexural strength and E-modulus were studied. The latter tests were carried out on both on concrete cured at 20 °C and concrete subjected to high-temperature conditions at 300 °C, 450 °C and 600 °C. The results enabled us to evaluate the effect of high-temperature conditions on the properties of high-performance concrete and compare the effectiveness of the two methods designed to improve the high-temperature performance of the concrete: addition of polypropylene fibres and entrainment of air.

scholarly journals Mechanical Properties of High-Performance Hybrid Fibre-Reinforced Concrete at Elevated Temperatures

2021 ◽  
Vol 13 (23) ◽  
pp. 13392
Author(s):  
Moawiah Mubarak ◽  
Raizal Saifulnaaz Muhammad Rashid ◽  
Mugahed Amran ◽  
Roman Fediuk ◽  
Nikolai Vatin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Fibre Reinforced Concrete ◽  
Explosive Spalling ◽  
Hybrid Fibre ◽  
Before And After

Deterioration of concrete’s integrity under elevated temperature requires an alteration in its composition to have better thermal stability. Fibre-reinforced concrete has shown significant improvements in concrete strength and this paper aimed to investigate the influence of steel (ST) and polypropylene (PP) fibres on the behaviour of high-performance concrete (HPC) exposed to elevated temperatures. Six mixtures were prepared and cast by adding one or two types of polypropylene fibre (54 and 9 mm) at 0.25 or 0.5% and either singly or in a hybrid combination, along with a fixed volumetric content at 1% of five-dimensional hooked steel (5DH) fibres. At the age of 28 days, samples were heated to the targeted temperature of 800 °C and cooled down naturally to the laboratory temperature. Visual inspection, flexural, split tensile and compressive strengths were examined before and after the exposure to elevated temperatures. Results exhibited that the hybridization of long and short PP fibres, along with the ST fibres, has notably improved all residual mechanical properties of HPC and kept the integrity of concrete after exposure to elevated temperatures. In addition, PP fibres can significantly prevent spalling, but ST fibres were ineffective in mitigating explosive spalling in beams specimens.

scholarly journals Effect of Moisture Content on the Behavior of High Strength Concrete at High Temperatures

2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Larissa Degliuomini Kirchhof ◽  
Rogério Cattelan Antocheves de Lima ◽  
Almir Barros da Santos Neto ◽  
Alana Costa Quispe ◽  
Luiz Carlos Pinto da Silva Filho
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
High Strength Concrete ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Strength ◽  
Experimental Program ◽  
High Moisture ◽  
Strength Concrete ◽  
Normal Strength

ABSTRACT In this paper, an experimental program was carried out to investigate the residual mechanical properties of high strength concrete and normal strength concrete, and how moisture content and temperature affect the spalling process. Three mixtures with water-cementitious material ratios, from 0.25 to 0.50, and with different saturation levels were heated in an electric furnace to elevated temperatures, from 200°C to 600°C. After heating, the specimens were cooled down to room temperature and then tested for compression and tensile strength. The results showed that high moisture content induces the spalling process and reduces considerably the mechanical properties of high strength concrete, mainly at temperatures above 400°C.

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