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Article
Publication date: 27 June 2019

Amir Hamzeh Keykha

This study aims to investigate the effect of high temperature (600°C) on the compressive strength of concrete covered with a mixture of polypropylene fiber and gypsum…

Abstract

Purpose

This study aims to investigate the effect of high temperature (600°C) on the compressive strength of concrete covered with a mixture of polypropylene fiber and gypsum plaster (PFGP).

Design/methodology/approach

To study the compressive strength of concrete specimens exposed to temperature, 16 cubic specimens (size: 150 mm × 150 mm × 150 mm) were made. After 28 days of processing and gaining the required strength of specimens, first, polypropylene fiber was mixed with gypsum plaster (CaSO4.2H2O) and then the concrete specimens were covered with this mixture. To cover the concrete specimens with the PFGP, the used PFGP thickness was 15 mm or 25 mm. The polypropylene rates mixed with the gypsum plaster were 1, 3 and 5 per cent. A total of 14 specimens, 12 of which were covered with PFGP, were exposed to high temperature in two target times of 90 and 180 min.

Findings

The results show that the PFGP as covering materials can improve the compressive strength lost because of the heating of the concrete specimens. The results also show that the presence of polypropylene fiber in gypsum plaster has the effect on the compressive strength lost because of the heating of the PFGP-covered concrete. The cover of PFGP having 3 per cent polypropylene fiber had the best effect on remained strength of the specimens.

Originality/value

The cover of PFGP having 3 per cent polypropylene fiber has the best effect on remained strength of the PFGP covered specimens exposed to temperature.

Details

Journal of Structural Fire Engineering, vol. 10 no. 4
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 22 March 2021

H.M. Iqbal Mahmud, Autri Mandal, Sudip Nag and Khalid A.M. Moinuddin

The purpose of this study is to investigate the performance of fire protective materials in protecting steel section. A new indexing system is introduced, named as fire…

Abstract

Purpose

The purpose of this study is to investigate the performance of fire protective materials in protecting steel section. A new indexing system is introduced, named as fire endurance index (FEI), which can be used to evaluate the performance of fire protective materials.

Design/methodology/approach

In this study, experiments were carried out using W4 × 13 steel section. Eight samples were prepared; one was a bare steel section without any coating material, and seven were prepared using four types of materials such as vermiculite-gypsum plaster, gypsum plaster, concrete cover and glass wool-concrete cover for fireproofing of the sections. An enclosed electric coiled furnace was used for heating the samples for a certain period. The duration of protection was determined, and the FEI of the materials was calculated. The higher the index value is, the better the performance.

Findings

The results demonstrate that the glass-wool-concrete cover offered the best performance at high temperature among the four types of materials. In the experiment with glass-wool-concrete cover, the furnace temperature reached 750°C, whereas the steel temperature reached only 100°C. The FEI of the coatings were calculated. Among the eight samples, glass wool-concrete cover also achieved the highest index value.

Research limitations/implications

The experimental work was performed using a limited number of specimens. Furthermore, the robustness of the indexing system needs to be evaluated with other materials and a wide range of heating rate and temperature. This study sets the foundation for future work.

Practical implications

The findings of this research may contribute to a better understanding of the performance of the materials used as fire protective coatings. This might be helpful for the researchers and practitioners in their design and implementation of legislation of fire safety codes.

Social implications

Understanding the performance of the fire protective coatings will help in evaluating the fire resistance capabilities of the materials to use for the structural steel members, which may protect collapses and disasters of buildings.

Originality/value

This paper deals with the performance of four types of materials, that can be used as fire protective coatings for structural steel members. Furthermore, the FEI explicitly indicated their performance with numerical values. In this study, the heating of the specimens was performed using a non-standard fire curve based on the concept that naturally occurring incidents of fire do not follow the standard fire curves.

Details

Journal of Structural Fire Engineering, vol. 12 no. 2
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 3 September 2019

Mariyana Aida Ab Kadir, Mohammad Iqbal Khiyon, Abdul Rahman Mohd. Sam, Ahmad Beng Hong Kueh, Nor Hasanah Abdul Shukor Lim, Muhammad Najmi Mohamad Ali Mastor, Nurizaty Zuhan and Roslli Noor Mohamed

The purpose of this paper is to examine the mechanical properties, material composition of spent garnet as a sand replacement in high-strength concrete at room and…

Abstract

Purpose

The purpose of this paper is to examine the mechanical properties, material composition of spent garnet as a sand replacement in high-strength concrete at room and elevated temperatures. Bonding of the concrete containing spent garnet and reinforcing rebar is investigated. Moreover, the optimum thickness of concrete cover subjected to elevated temperatures is investigated.

Design/methodology/approach

First, the plain spent garnet was physically, chemically and thermally studied. Then, a series of concrete specimens with 0, 20, 40, 60, 80 and 100 per cent of spent garnet were prepared to determine the optimum percentage of spent garnet. Finally, the physical and mechanical behaviours of concrete specimens and effects of cover thickness on steel rebar when subjected to elevated temperature of 200°C, 400°C, 600°C and 800°C for 1 h were studied. It was observed that spent garnet was thermally stable compared to river sand.

Findings

Mechanical properties were found to be optimal for concrete with 40% spent garnet replacement. Physically, spent garnet concrete changed colour to brown at 400°C, and to whitish grey at 600°C. The residual compressive strength of spent garnet concrete was also found slightly higher than that for control specimens. At various high temperatures, the reduction in ultimate tensile stress for steel bar inside concrete cover of 30 mm was the lowest compared to that of 20 mm.

Research limitations/implications

Spalling effect it not considered in this study.

Practical implications

The optimum concrete cover is important issues in reinforced concrete design. This can be used as a guideline by structural designers when using a different type of concrete material in the construction.

Social implications

Utilization of the waste spent garnet reduces usage of natural aggregates in concrete production and enhances its performance at elevated temperatures. Natural aggregates are normally taken from sand and rock. The new innovation in concrete perhaps can produce light concrete, reduce the cost of concrete production and at the same time also mitigates environmental problems affect from waste material such as minimizing disposal area.

Originality/value

Utilization of spent garnet in ordinary Portland cement (OPC) concrete at high temperature is a new innovation. It shows that the concrete cover of the concrete element reduced as compared to the OPC concrete. Reduce in weight concrete however the strength of concrete is similar to conventional concrete. This study at elevated temperature has never been performed by any previous researcher.

Details

Journal of Structural Fire Engineering, vol. 10 no. 4
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 16 August 2019

Virendra Kumar

This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated…

Abstract

Purpose

This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated temperatures.

Design/methodology/approach

The test variables included temperature of exposure, spacing of transverse confining reinforcement and pre-damage level. An experimental program was designed and carried out involving testing of hoop confined concrete cylindrical specimens exposed to elevated temperatures ranging from room temperature to 900 °C.

Findings

The test results indicate that the residual strength, strain corresponding to the peak stress and the post-peak strains of confined concrete are not affected significantly up to an exposure temperature of 300 °C. However, the peak confined stress falls and the corresponding strain increase considerably in the temperature range of 600 to 900 °C. It is shown that an increase in the degree of confinement reinforcement results in an increased residual strength and deformability of pre-damaged confined concrete.

Research limitations/implications

It is applicable in finding the residual strength and strain of the pre-damaged confined concrete in uni-axial compression after exposure to elevated temperature.

Practical implications

The practical implications is that the test result is applicable in finding the residual strengths of pre-damaged confined concrete under uni-axial compression after exposure to elevated temperature.

Social implications

The main aim of the present investigation is to provide experimental data on the residual behaviour of pre-damaged confined concrete subjected to high temperatures.

Originality/value

The results of this study may be useful for developing the guidelines for designing the confinement reinforcement of reinforced concrete columns against the combined actions of earthquake and fire, as well as for designing the retrofitting schemes after these sequential disasters.

Details

Journal of Structural Fire Engineering, vol. 11 no. 1
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 1 January 1990

Roel van Es

Discusses the properties of concrete and the process of carbonationwhich can lead to corrosion and its ultimate destruction. Outlines theconditions which lead to…

Abstract

Discusses the properties of concrete and the process of carbonation which can lead to corrosion and its ultimate destruction. Outlines the conditions which lead to carbonation, detailing design faults which facilitate the process, and suggests preventatives which can protect the surface. Examines the results of carbonation, the forming of distressed concrete and mentions tests which can be performed to check the health of the structure. Assesses the impact of additional factors leading to corrosion and offers advice on remedial actions.

Details

Structural Survey, vol. 8 no. 1
Type: Research Article
ISSN: 0263-080X

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Article
Publication date: 1 April 1983

H. McArthur

About 26,000 Airey Houses were erected during the post war years (1946–55) as part of the house building programme of that period. The Airey House is essentially a…

Abstract

About 26,000 Airey Houses were erected during the post war years (1946–55) as part of the house building programme of that period. The Airey House is essentially a prefabricated concrete structure which was erected on site to form a box. This box was erected upon a concrete raft which acted as the foundation and floor of the dwelling. The basic box was formed from several framed ‘goal posts’ to which thin concrete cladding panels were fastened to the upright columns by copper wire. The vertical loading from the first floor and roof is taken on the vertical columns but may also be shared with the concrete cladding panels (see Figure 1).

Details

Structural Survey, vol. 1 no. 4
Type: Research Article
ISSN: 0263-080X

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Article
Publication date: 3 February 2020

Utino Worabo Woju and A.S. Balu

Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design…

Abstract

Purpose

Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design and construction techniques, but the environmental factors are difficult to control. Hence, mostly in practice, the environmental factors are not considered in the analysis and design appropriately; however, their impact on the performance of the structures is significant along with the design life. It is in this light that this paper aims to perform the time-dependent performance analysis of reinforced concrete structures majorly considering environmental factors.

Design/methodology/approach

To achieve the intended objective, a simply supported reinforced concrete beam was designed and detailed as per the Euro Code (EC2). The time-dependent design parameters, corrosion parameters, creep and shrinkage were identified through thorough literature review. The common empirical equations were modified to consider the identified parameters, and finally, the time-dependent performance of reinforced concrete beam was performed.

Findings

Findings indicate that attention has to be paid to appropriate consideration of the environmental effect on reinforced concrete structures. In that, the time-dependent performance of reinforced concrete beam significantly decreases with time due to corrosion of reinforcement steel, creep and shrinkage.

Originality/value

However, the Euro code, Ethiopian code and Indian code threat the exposure condition of reinforced concrete by providing corresponding concrete cover that retards the corrosion initiation time but does not eliminate environmental effects. The results of this study clearly indicate that the capacity of reinforced concrete structure degrades with time due to corrosion and creep, whereas the action on the structure due to shrinkage increases. Therefore, appropriate remedial measures have to be taken to control the defects of structures due to the environmental factors to overcome the early failure of the structure.

Details

Journal of Engineering, Design and Technology , vol. 18 no. 5
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 27 May 2014

Christos Zeris, George Batis, Vassilios Mouloudakis and John Marakis

This paper aims to present results of an experimental investigation on a series of scaled reinforced concrete column elements which were subjected to chloride exposure…

Abstract

Purpose

This paper aims to present results of an experimental investigation on a series of scaled reinforced concrete column elements which were subjected to chloride exposure under accelerated conditions under a concurrent service axial load, over a period. In the presence of an axial load, directed microcracks of increasing density and width are introduced in the concrete mass, depending on the axial load level. Such cracks are believed to enhance the intrusion rate of chlorides in the concrete, relative to what is obtained in the normally performed unloaded specimen tests.

Design/methodology/approach

Eighteen column specimens were tested over two chloride exposure periods, of duration up to a maximum of six months. Three different service axial load levels were considered, namely, none, 22 per cent and 43 per cent of the normalized axial load capacity of the columns.

Findings

The results indicate that the specimens loaded to the higher axial load, which closely resembles actual service situation of such type of elements, exhibited up to ten times faster rates of induced current flow under a constant applied voltage of 500 mV, compared to the unloaded and less loaded specimens.

Practical implications

It is proven that the presence of axial load influences the rate of chloride ingress in columns and, therefore, should be taken into account in estimating the concrete cover of such elements in durability design.

Originality/value

The influence of axial loading on corrosion rate has not been considered in published experimental and analytical studies of chloride ingression. These studies have typically so far considered the accelerated corrosion of unloaded column specimens.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 July 1992

Adel El‐Kurdey and Ashraf Y. Hosny

The corrosion of reinforcing steel is considered the most critical problem for the durability of reinforced concrete structures. This study shows the experimental results…

Abstract

The corrosion of reinforcing steel is considered the most critical problem for the durability of reinforced concrete structures. This study shows the experimental results of the corrosion of steel bars in mortar, using an accelerated test. The results indicate that increasing water/cement ratios accelerate the corrosion of reinforcing steel. In addition, increasing curing times decrease steel corrosion rates. The results also show that the cover to bar diameter ratio plays a significant role in determining the corrosion intensity. For the same cover thickness, the corrosion intensity increases as the steel bar diameter increases.

Details

Anti-Corrosion Methods and Materials, vol. 39 no. 7
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 27 September 2021

Radhia Chabbi, Noureddine Ferhoune and Fouzia Bouabdallah

This research aims to study the materials that compose older reinforced concrete bridges which are damaged and degrading to explain the mechanisms and origins of various…

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Abstract

Purpose

This research aims to study the materials that compose older reinforced concrete bridges which are damaged and degrading to explain the mechanisms and origins of various disorders. Therefore, this work will contribute to providing answers on the capacity of nondestructive evaluation method during the diagnosis. In addition to the characterization of affected structures, it will aim to provide effective solutions for different serious pathologies.

Design/methodology/approach

In this context, two bridges located on NH16 and NH21, respectively, were studied in Annaba city (north-east Algeria), specifically in El-Hadjar municipality located in the central industrial zone of Pont-Bouchet. This study makes it possible to make conclusions from the in-depth diagnosis based on disorders exposition causes and mechanical characteristics evolution by non-destructive testing (NDT) tools. Furthermore, solutions are proposed, including conservation maintenance of these degraded structures.

Findings

All degradations can be the result of several factors: either human (poor design) or chemical (surface water, wastewater and groundwater quality (acidic or basic)). In addition to other natural causes (geological formations, flood phenomena or climate), NDT tools play a major role in the evaluating mechanical performance of degraded structures (resistance and hardness).

Research limitations/implications

The NDT techniques can be transmitted to civil engineering experts because their training is limited regarding mechanical and structural construction.

Practical implications

NDT tools are the most suitable for in-situ assessing, and the concrete constructions health state, so far from financial problems.

Social implications

Degraded bridge diagnosis by NDT testing is necessary for a thorough safety evaluation (mechanical performance, strength and deformability), to protect human lives and design durability.

Originality/value

This is an original paper which contains new information at different scales and from special fields, based on an evaluation using NDT tools on real degraded structures. It can be used to improve the knowledge of materials employed in a bridge without performing expensive direct tests or the need for destroying it.

Details

International Journal of Building Pathology and Adaptation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2398-4708

Keywords

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