Concrete at temperatures above 1000°C

Chang, Wei-Tun; Wang, Chen-Then; Huang, Chin‐Wang; Giang, Yun-Seng

doi:10.1016/0379-7112(94)90030-2

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…There is a 0.85%-point rise in the specific volume. The calcium hydroxide and other products of cement hydration start to dehydrate, which is one factor that contributes to the concrete structure's deterioration (Chang et al, 1994).…”

Section: Compressive Strengthmentioning

confidence: 99%

Development of high-temperature heavy density dolerite concrete for 4th generation nuclear power plants

Khan

Malik²,

Yaqub³

et al. 2023

Front. Mater.

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This study examines the physical, mechanical, microstructural, and attenuation properties of high-density concrete exposed to temperatures ranging from 200°C to 1200°C. For this purpose, heavy-density concrete containing 25%, 50%, 75%, and 100% dolerite aggregates was developed and compared with three ordinary concrete mixes. Pre- and post-heated concrete specimens were evaluated for mass and density loss, compressive strength, rebound hammer, X-ray and gamma-ray attenuation, Half Value Layer (HVL), and Ten Value Layer (TVL) along with microstructural properties determined by scanning electron microscopy and Energy Dispersive X-ray. The results showed that the incorporation of 75% dolerite aggregate during pre- and post-heating yielded high compressive strength whereas low mass and density loss. The same mixture showed significant improvement in gamma ray shielding at all temperatures. The Half Value Layer and Ten Value Layer values showed a reduction in the thickness of concrete as a shield. It is recommended that dolerite heavy-density concrete is a potential radiation shield at high temperatures ranging from 200°C–1200°C in fourth-generation nuclear power plants.

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Section: Compressive Strengthmentioning

confidence: 99%

Development of high-temperature heavy density dolerite concrete for 4th generation nuclear power plants

Khan

Malik²,

Yaqub³

et al. 2023

Front. Mater.

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“…At very high temperatures, melted cement paste (high Calcium content) and aggregate (high Silicon content) may change their own relative distribution by flowing around and thus changing their relative elemental abundance near surface [11].…”

Section: Sand Particle 5mm Lp-c(dry) Hp-c(dry) Lp-c(dry) Lp-c(wet)mentioning

confidence: 99%

Effects of Laser Cleaning on Chemical Composition of Mortar Surfaces

Klemm

Sanjeevan²

2008

TOBCTJ

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Abstract:The paper presents a part of the larger study on microstructural features of mortars and their effects on laser cleaning process. It focuses on presenting the results of investigation on the influence of laser cleaning on chemical composition of mortar surfaces. The experimental results prove that the laser cleaning process leads to an increase of Si element concentration and/or decrease in Ca concentration. The observed alterations should be associated with changes in the relative distribution of melted cement paste and aggregate and therefore relative elemental abundance in the near-surface layer. Furthermore, curing and service conditions of mortars seem to have strong influence on laser cleaning process and therefore on surface quality. Exposure to freezing/thawing cycles and subsequent surface damage facilitates deeper penetration of paint and consequently affects the efficiency of cleaning. The amount of residual carbon on F/T samples tested in the course of this study was around 42% higher than on the surfaces of laboratory-cured samples.

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“…However, the elevated temperatures of a fire and the temperature gradient within the body due to concrete's low thermal conductivity can create an even greater driving force for water to evaporate out of the concrete. These detrimental affects on concrete have been studied extensively since 1930 (Ahlers 1930;Abrams 1973;Diederichs et al 1988;Chang et al 1993;Chan et al 1999;Ulm et al 1999;Phan 2000). The decrease in the strength of fire-exposed concrete has led to the inclusion of fire-endurance specifications of concrete in structural design codes.…”

Section: Introductionmentioning

confidence: 99%

Transport Properties of Fire-Exposed Concrete

Vichit-Vadakan

Kerr

2009

ACT

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Concrete has a good reputation for fire resistance because it has low thermal conductivity and is non-combustible. However, concrete loses strength when exposed to elevated temperatures as a result of damage to the pore structure and chemical degradation of the calcium silicate hydrate. Reports on strength loss due to fire exposure are ubiquitous in the literature. However, there have been limited reports on the changes in the pore structure, which greatly affects the durability of the concrete. In cases where the strength is sufficient for the structural element to remain in service, other considerations, such as the durability of the structural element comes into play. The ingress of aggressive agents is typically through means, such as water, which leads to sorptivity being a particular important transport property of the degraded concrete. The sorptivity of the concrete will depend on the age of the sample at the time of damage, the cement content, w/c of the original mix design, as well as the length of time the damaged concrete has been re-exposed to water. These properties are reported along with mechanical properties to better demonstrate the complexity in the relationship between transport properties and strength. Furthermore, sorptivity can become crucial to predicting long term durability as well as identifying potential repair mechanisms.

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Concrete at temperatures above 1000°C

Cited by 7 publications

References 10 publications

Development of high-temperature heavy density dolerite concrete for 4th generation nuclear power plants

Development of high-temperature heavy density dolerite concrete for 4th generation nuclear power plants

Effects of Laser Cleaning on Chemical Composition of Mortar Surfaces

Transport Properties of Fire-Exposed Concrete

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