Explosive spalling and residual mechanical properties of fiber-toughened high-performance concrete subjected to high temperatures

2006 ◽  
Vol 36 (4) ◽  
pp. 723-727 ◽  
Author(s):  
Gai-Fei Peng ◽  
Wen-Wu Yang ◽  
Jie Zhao ◽  
Ye-Feng Liu ◽  
Song-Hua Bian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Explosive Spalling ◽  
Residual Mechanical Properties

scholarly journals Mechanical Properties of Ultra-High Performance Concrete before and after Exposure to High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 770 ◽  
Author(s):  
How-Ji Chen ◽  
Yi-Lin Yu ◽  
Chao-Wei Tang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Silicon Powder ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Splitting Strength ◽  
Experimental Group

Compared with ordinary concrete, ultra-high performance concrete (UHPC) has excellent toughness and better impact resistance. Under high temperatures, the microstructure and mechanical properties of UHPC may seriously deteriorate. As such, we first explored the properties of UHPC with a designed 28-day compressive strength of 120 MPa or higher in the fresh mix phase, and measured its hardened mechanical properties at seven days. The test variables included: the type of cementing material and the mixing ratio (silica ash, ultra-fine silicon powder), the type of fiber (steel fiber, polypropylene fiber), and the fiber content (volume percentage). In addition to the UHPC of the experimental group, pure concrete was used as the control group in the experiment; no fiber or supplementary cementitious materials (silica ash, ultra-fine silicon powder) were added to enable comparison and discussion and analysis. Then, the UHPC-1 specimens of the experimental group were selected for further compressive, flexural, and splitting strength tests and SEM observations after exposure to different target temperatures in an electric furnace. The test results show that at room temperature, the 56-day compressive strength of the UHPC-1 mix was 155.8 MPa, which is higher than the >150 MPa general compressive strength requirement for ultra-high-performance concrete. The residual compressive strength, flexural strength, and splitting strength of the UHPC-1 specimen after exposure to 300, 400, and 500 °C did not decrease significantly, and even increased due to the drying effect of heating. However, when the temperature was 600 °C, spalling occurred, so the residual mechanical strength rapidly declined. SEM observations confirmed that polypropylene fibers melted at high temperatures, thereby forming other channels that helped to reduce the internal vapor pressure of the UHPC and maintain a certain residual strength.

Thermal properties of jute fiber concrete at high temperature

2016 ◽  
Vol 7 (3) ◽  
pp. 182-192 ◽  
Author(s):  
Mitsuo Ozawa ◽  
Gyu-Yong Kim ◽  
Gyeong-Choel Choe ◽  
Min-Ho Yoon ◽  
Ryoichi Sato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
High Temperatures ◽  
High Performance Concrete ◽  
Synthetic Fiber ◽  
Jute Fiber ◽  
Explosive Spalling ◽  
Content Type ◽  
Fiber Addition

Purpose The behavior of high-performance concrete (HPC) at high temperatures is very complex and also affects the global behavior of heated HPC-based structures. Researchers have also reported how various types of fibers affected the mechanical properties of cement-based materials at high temperatures. This study aims to discuss the effects of high temperatures on the compressive strength and elastic modulus of HPC with polypropylene (PP) and jute fiber. Design/methodology/approach Adding synthetic fiber (especially the PP type) to HPC is a widely used and effective method of preventing explosive spalling. Although researchers have experimentally determined the permeability of heated PP-fiber-reinforced HPC, few studies have investigated how adding natural fiber such as jute to this type of concrete might prevent spalling. In this study, the effects of high temperatures on the compressive strength and elastic modulus of HPC with PP and jute fiber (jute fiber addition ratio: 0.075 vol.%; length: 12 mm; PP fiber addition ratio: 0.075 vol.%; length: 12 mm) were experimentally investigated. Findings The work was intended to clarify the influence of elevated temperatures ranging from 20°C to 500°C on the material mechanical properties of HPC at 80 MPa. HSC with jute fiber showed a compressive strength loss of about 40 per cent at 100°C before recovering to full strength between 200°C and 300°C. Originality/value The elastic modulus of high-strength concrete decreased by 10-40 per cent between 100°C and 300°C. At 500°C, the elastic modulus was only 30 per cent of the room temperature value. The thermal expansion strain of all specimens was 0.006 at 500°C.

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 Mechanical Properties and Anti-Spalling Behavior of Ultra-High Performance Concrete with Recycled and Industrial Steel Fibers

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 783 ◽  
Author(s):  
Juan Yang ◽  
Gai-Fei Peng ◽  
Guo-Shuang Shui ◽  
Gui Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fracture Energy ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Ultra High Performance Concrete ◽  
Explosive Spalling ◽  
Recycled Steel

Experimental investigations on the mechanical properties of ultra-high performance concrete (UHPC) incorporating two types of recycled steel fiber processed from waste tires and three types of industrial steel fiber were carried out for comparison. Mechanical properties of UHPC include compressive strength, splitting tensile strength, fracture energy, and elastic modulus. Their explosive spalling behaviors under high temperatures were also investigated. The results show that all types of steel fiber exhibit a beneficial effect on the mechanical properties and the anti-spalling behavior of UHPC, except that recycled steel fiber with rubber attached (RSFR) has a slightly negative effect on the compressive strength of UHPC. Compared to industrial steel fibers, recycled steel fibers have a more significant influence on improving the splitting tensile strength and fracture energy of UHPC, and the improvement of RSFR was much higher than that of recycled steel fiber without rubber (RSF). UHPC that incorporates industrial hooked-end steel fiber (35 mm in length and 0.55 mm in diameter) exhibits the best resistance to explosive spalling, and the second is the RSF reinforced UHPC. The positive relationship between the fracture energy and the anti-spalling behavior of steel fiber reinforced UHPC can be presented. These results suggest that recycled steel fiber can be a toughening material and substitute for industrial steel fibers to be used in ultra-high performance concrete, especially RSFR.

scholarly journals Flexural Behavior of Ultra-High-Performance Fiber-Reinforced Concrete Beams after Exposure to High Temperatures

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5400
Author(s):  
How-Ji Chen ◽  
Chien-Chuan Chen ◽  
Hung-Shan Lin ◽  
Shu-Ken Lin ◽  
Chao-Wei Tang
Keyword(s):  
High Temperatures ◽  
High Performance ◽  
Room Temperature ◽  
High Performance Concrete ◽  
Point Load ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Beam Specimen ◽  
Explosive Spalling

Due to the dense structure of ultra-high-performance concrete (UHPC), it is prone to explosive spalling at high temperatures. In this paper, flexural testing of UHPC and high-strength concrete (HSC) beams was carried out at room temperature and after being subjected to different levels of thermal exposure (300–500 °C). The cross-section of the beam specimen was 150 (width) × 200 (depth) mm, and its length was 1500 mm. The flexural and shear design of the beam specimens were carried out in accordance with the ACI 318M-14 code. All of the beams were singly reinforced with two #4 rebars (minimum reinforcement ratio) as a longitudinal tensile reinforcement at the bottom of the specimen and at an effective depth of 165 mm. The flexural load was applied using the three-point load method. The results show that, at room temperature and after being subjected to different thermal exposures, compared with the HSC specimens, the stiffness of the UHPC specimens in the post-cracking stage was relatively larger and the deflection under a given load was smaller. Moreover, whether at room temperature or after exposure to different thermal exposures, the ductility of the UHPC specimens was better than that of the HSC specimens.

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