On the thermal spalling mechanism of reactive powder concrete exposed to high temperature: Numerical and experimental studies

Ju, Yang; Liu, Jinhui; Liu, Hongbin; Tian, Kaipei; Ge, Zhishun

doi:10.1016/j.ijheatmasstransfer.2016.03.033

Cited by 41 publications

(8 citation statements)

References 59 publications

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“…Unlike the ambient temperature studies, it cannot be ignored in high-temperature conditions [62]. Tensile strength resists the crack propagation and, furthermore, it safeguards concrete against build-up vapor pressure at high temperature and resists fire-induced spalling [63,64,65]. The evolution of split-tensile strength of SRPC, PRPC, and HRPC with high temperature is shown in Figure 6a.…”

Section: Test Results and Discussionmentioning

confidence: 99%

Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete

et al. 2019

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This study was aimed to investigate the effect of steel, polypropylene (PP), and hybrid (steel + PP) fibers on high-temperature mechanical properties of reactive powder concrete (RPC). The mechanical properties considered are cubic compressive strength, axial or prismatic compressive strength, split-tensile strength, flexural strength, elastic modulus, peak strain, and stress-strain behavior. The strength recession due to high temperature was investigated at micro level by scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, mercury intrusion porosity, thermogravimetric, and differential scanning calorimetry analyses. The high-temperature tests were carried out at target temperatures of 120, 300, 500, 700, and 900 °C. The hot-state compressive strength of RPC started to decrease at 120 °C; however, a partial recovery at 300 °C and a gradual decrease above 300 °C were observed. The degradation of split-tensile strength, flexural strength, and elastic modulus were gradual with increasing temperature despite the effect of different fibers. Whereas, the peak strain was gradually increasing up to 700 °C. However, after 700 °C, it remained unchanged. Steel fiber reinforced RPC (SRPC) and hybrid fiber reinforced RPC (HRPC) showed a ductile behavior. PP fiber reinforced RPC (PRPC) showed a quite brittle behavior up to 300 °C; however, further heating made the microstructure porous and it became ductile too. Overall the performance of SRPC and HRPC were superior to PRPC because of higher modulus of elasticity, higher strength, and better fire resistance of steel fibers. Fiber reinforced RPC was found to have better fire resistance than traditional types of concrete based on comparative studies with the provisions of design codes and earlier research. The constitutive equations developed can be utilized in computer programs for structural design of RPC structures exposed to fire.

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Section: Test Results and Discussionmentioning

confidence: 99%

Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete

et al. 2019

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“…Aging in reinforced concrete (RC) structures occurs due to a combination of physical [ 1 , 2 , 3 ], thermal [ 4 , 5 ], chemical [ 6 , 7 , 8 , 9 ] and mechanical [ 10 ] effects. The aging mechanisms may include cracking due to temperature variations [ 11 ], creep and shrinkage [ 12 ], the alkali–silica reactivity (ASR) of concrete [ 13 , 14 , 15 ] and the corrosion of reinforcing bars (rebar) [ 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Impact of Laboratory-Accelerated Aging Methods to Study Alkali–Silica Reaction and Reinforcement Corrosion on the Properties of Concrete

Attar¹,

Gencturk

Aryan

et al. 2020

Materials

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This study focuses on two separate investigations of the main aging mechanisms: alkali–silica reactivity (ASR) and the corrosion of reinforcing steel (rebar) concrete, both of which may result in a premature failure to meet the serviceability or strength requirements of a concrete structure. However, these processes occur very slowly, spanning decades. The impact of direct chemical additives to fresh concrete to accelerate ASR and the corrosion of reinforcing steel on the fresh and hardened properties of the ensuing material are investigated to inform the potential use of chemicals in large-scale studies. The deterioration of reinforced concrete (RC) is determined by means of expansion, cracking, bulk diffusivity and surface resistivity measurements, and compressive, split tensile and flexural strength tests. The results indicate that the addition of sodium hydroxide and calcium chloride can effectively accelerate the crack formation and propagation in concrete due to ASR and the corrosion of rebar, respectively. The ASR-induced cracks maintained a constant crack width from 0.05 mm to 0.1 mm over the measurement period regardless of the intensity of aging acceleration. Adding 4% chloride by weight of cement for accelerating rebar corrosion resulted in an average crack that was 82% larger than in the case of ASR accelerated with the addition of sodium hydroxide. The addition of alkali resulted in an increase in early-age (7-day) strength. At a total alkali loading of 2.98 kg/m3, 3.84 kg/m3 and 5.57 kg/m3, the 28-day compressive strength of concrete decreased by 3%, 10% and 24%, respectively. Similarly, a higher early-age strength and a lower later-age strength was observed for the concrete in the presence of corrosive calcium chloride. The results from this research are expected to inform future studies on the long-term performance of RC structures under accelerated ASR and corrosion.

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“…Xotta et al [20] investigated the effects of the porosities of aggregate and cement paste on the internal stresses of heated concrete under slow and fast heating conditions at a meso-level. Based on the experiments and by analyzing the thermal stress development, Ju et al [21] modeled the spalling process of reactive powder concrete specimens exposed to slow heating with a heating rate of 4.8 o C/min.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of heating rate effect on spalling of high-performance concrete under high temperature conditions

Zhao

Zheng

Peng

et al. 2017

Construction and Building Materials

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High-performance concrete (HPC) is vulnerable to spalling under high temperature conditions and it has been found that the heating rate can exert a tremendous effect on spalling of HPC. To prevent HPC from spalling, the heating rate effect should be understood.However, quantitative analyses are still lacking and the heating rate effect has not been well interpreted so far. In this paper, a numerical analysis of the heating rate effect on spalling of HPC is presented. Based on the experimental results reported in the literature, the spalling behavior of cubic HPC specimens under fire heating and slow heating with a heating rate of 5 o C/min is modeled. With a meso-level thermo-chemo-hydro-mechanical analysis, the temperature gradient induced thermal stress and the mechanical effect of build-up vapor pressure are investigated. The results show that, at different heating rates, the spalling mechanisms are different. Finally, possible manners and mechanisms of spalling are discussed.

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On the thermal spalling mechanism of reactive powder concrete exposed to high temperature: Numerical and experimental studies

Cited by 41 publications

References 59 publications

Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete

Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete

Impact of Laboratory-Accelerated Aging Methods to Study Alkali–Silica Reaction and Reinforcement Corrosion on the Properties of Concrete

Numerical analysis of heating rate effect on spalling of high-performance concrete under high temperature conditions

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