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Article
Publication date: 18 March 2014

N. Anand, G. Arulraj and C. Aravindhan

Development of Self Compacting Concrete (SCC) is considered as one of the most significant development in the construction industry due to its numerous inherited benefits…

Abstract

Development of Self Compacting Concrete (SCC) is considered as one of the most significant development in the construction industry due to its numerous inherited benefits. With the introduction of super-plasticizers and viscosity modifying agents, it is now possible to produce concrete with high fluidity, good cohesiveness which does not require external energy for compaction. The proper understanding of the effects of elevated temperatures on the properties of SCC is necessary to ensure the safety of buildings made with SCC during fire. During the present investigation, an attempt has been made to study the stress-strain behaviour of Normal Compacting Concrete (NCC) and Self Compacting Concrete at a temperature of 900°C. A significant reduction in the Ultimate compressive strength of SCC was observed during this study. The reduction was found to be more for SCC compared to Normal compacting concrete. The reduction in the compressive strength of SCC was found to be 81.5 % for M40 concrete when exposed to 900°C.

Details

Journal of Structural Fire Engineering, vol. 5 no. 1
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 5 June 2012

A. Rahim, U. Sharma, K. Murugesan, A. Sharma and P. Arora

This paper presents results of an experimental study undertaken to optimize the residual compressive strength of heated concrete with respect to various mix design…

Abstract

This paper presents results of an experimental study undertaken to optimize the residual compressive strength of heated concrete with respect to various mix design parameters using the Taguchi method. The design of experiments (DoE) was carried out by standard L9 (34) orthogonal array (OA) of four factors with three material parameter levels. The factors considered were water-cement ratio, cement content, super-plasticizer dosage and fine aggregate content. The specimens were heated up to 200°C, 400°C, 600°C and 800°C target temperatures and were subsequently tested under axial compressive loads in cooled condition. Based on the results, the material parameter responses of optimum performance characteristics were analyzed by statistical analysis of signal to noise ratio (S/N) and analysis of variance (ANOVA) techniques to maximize the post-fire residual compressive strength of concrete. The results indicate that the best level of control factors paid their own contribution of compressive strength at various elevated temperatures. The confirmation tests corroborated the theoretical optimum test conditions.

Details

Journal of Structural Fire Engineering, vol. 3 no. 2
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 16 August 2019

Yasmin Murad, Rana Imam, Husam Abu Hajar, Dua’a Habeh, Abdullah Hammad and Zaid Shawash

The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as…

Abstract

Purpose

The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as accurate models that can predict the compressive strength of green concrete are still lacking.

Design/methodology/approach

To estimate the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, four predictive GEP models are developed. The GEP models are developed using a large and reliable database that is collected from the literature. The GEP models are validated using the collected experimental database.

Findings

The R2 is used to statistically evaluate the performance of the GEP models wherein the R2 values for the GEP models including all data are 85, 95, 80 and 95.3 percent for the models that predict the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, respectively.

Originality/value

The GEP models have high R2 values and low RMSE and MAE, which indicates that they are capable of predicting the compressive strength of green concrete with a reasonable accuracy.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 14 July 2021

Sachin B.P. and N. Suresh

The purpose of the paper is to study the effect of elevated temperature on load carrying capacity of reinforced self compacting concrete beams and the performance of…

Abstract

Purpose

The purpose of the paper is to study the effect of elevated temperature on load carrying capacity of reinforced self compacting concrete beams and the performance of deteriorated beams after retrofitting by GFRP sheets. The reinforced beams which were exposed to sustained elevated temperature and tested for flexural load-carrying capacity. Further deteriorated beams (exposed from 500°C to 800°C) were re-strengthened by adopting retrofitting with GFRP sheets.

Design/methodology/approach

The investigation includes the concrete specimens, i.e. cubes of 150 mm, cylinders of size 150 mm dia with 300 mm height and beams of 150 × 150 × 1,100 mm, reinforced with minimum tension reinforcement according to IS 456–2000. The specimens were subjected to elevated temperature from 300°C to 800°C with an interval of 100°C for 2 h. The residual compressive strength, modulus of elasticity, load at first crack of beams and load-carrying capacity of beams for 5-mm deflection were measured before and after retrofitting.

Findings

The result shows that there is a gain in residual compressive strength at 300°C and beyond which it decreases. The modulus of elasticity, load at first crack and load-carrying capacity of beams reduces continuously with an increase in temperature. The decrease in load-carrying capacity of beams is observed from 27.55% and up to 38.77% between the temperature range of 500°C–800°C and after the retrofitting of distressed beams, the load carrying capacity increases up to 24.48%.

Originality/value

Better performance was observed with retrofitting by GFRP sheets when the specimens were distressed due to elevated temperatures.

Details

Journal of Structural Fire Engineering, vol. 12 no. 3
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 19 May 2021

Peerzada Mudasir and Javed Ahmed Naqash

The aim of this research is to study the role and formation of hydration products particularly crystalline portlandite Ca(OH)2 in MWCNT-reinforced concrete at 28 days…

Abstract

Purpose

The aim of this research is to study the role and formation of hydration products particularly crystalline portlandite Ca(OH)2 in MWCNT-reinforced concrete at 28 days. Concrete is the largest manufactured building material in world in which cement, sand aggregates and water cement ratio plays governing role. Water–Cement ratio decides it strength, usage, serviceability and durability. As strength of concrete depends on formation of crystalline hydrates; therefore, water–cement ratio can alter formation of hydrates also. Unfortunately, concrete is the most brittle material and to overcome brittleness of conventional concrete is tailored with some fibers. Till now, multiwalled carbon nano tubes are the most tensile and strongest materials discovered. Addition of multiwalled carbon nano tubes changes basic properties of conventional concrete. Therefore, it is important to evaluate formation of crystalline hydrates in multiwalled carbon nano tube–reinforced concrete by micro structure analysis.

Design/methodology/approach

Till now, multiwalled carbon nano tube–reinforced concrete has not been analyzed at micro structure level. To accomplish the objective, four concrete mixes with 0.45, 0.48, 0.50 and 0.55 water–cement ratio having 0.5 and 1% multiwalled carbon nano tubes incorporated by weight of cement, respectively. For hardening property analysis, compressive strength was obtained by crushing cubes; flexural strength was obtained by three-point loading; and split tensile strength was obtained by splitting cylindrical specimens. For analyzing role and formation of crystalline portlandite Ca(OH)2 hydrates, X-ray diffraction test was conducted on 75-µ dust of each mix. Scanning electron microscopy analysis was performed on fractured samples of crushed cubes of multiwalled carbon nano tube–reinforced concrete samples to check aggloremation.

Findings

It was observed multiwalled carbon nano tubes successfully enhanced compressive strength, flexural strength and split tensile strength by 8.89, 5.33 and 28.90%, respectively, in comparison to reference concrete at 0.45 water–cement ratio and 0.5% multiwalled carbon nano tubes by weight of cement. When its content was increased from 0.5 to 1% by weight of cement compressive strength, flexural strength and split tensile strength diminished by 2.04, 0.32 and 1.18%, respectively, at 0.45 water–cement ratio. With the increment of water–cement ratio, overall strength decreased in all mixes, but in multiwalled carbon nano tube–reinforced concrete mixes, strength was more than reference mixes. In reference, concrete at 0.45 water–cement ratio crystalline portlandite Ca(OH)2 crystals are of nano metre size, but in carbon nano tube–reinforced concrete mix having 0.45 water–cement ratio and 0.5% multiwalled carbon nano tubes by weight of cement, its size is much smaller than reference mix, thereby enhancing mechanical strength. In reference, concrete at 0.55 water–cement ratio size of crystalline portladite Ca(OH)2 crystals is large, but with incorporation of multiwalled carbon nano tubes, their size reduced, thereby enhancing mechanical strength of carbon nano tube–reinforced concrete having 0.55 water–cement ratio and 0.5 and 1% multiwalled carbon nano tubes by weight of cement, respectively. Also at 1% multiwalled carbon nano tubes by weight of cement, agglomeration and reduction in formation of crystalline portlandite Ca(OH)2 crystals were observed. Multiwalled carbon nano tubes effectively refine pores and restrict propagation of micro cracks and act as nucleation sites for Calcium-Silicate-Hydrate phase. Geometry of crystalline axis of fracture for portlandite Ca(OH)2 crystals is altered with incorporation of multiwalled carbon nano tubes. Crystalline portlandite Ca(OH)2 crystals and bridging effect of multiwalled carbon nano tubes is governing factor for enhancing strength of multiwalled carbon nano tube reinforced concrete.

Practical implications

Multiwalled carbon nano tube–reinforced concrete can be used to make strain sensing concrete.

Originality/value

Change in geometry and size of axis of fracture of crystalline portladite Ca(OH)2 crystals with incorporation of multiwalled carbon nano tubes.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 22 October 2020

Angelo De Luca, Linda Chen and Koorosh Gharehbaghi

Due to the high demand of concrete, significant volume of natural resources is required, including virgin aggregates. Many studies have shown that the production of…

Abstract

Purpose

Due to the high demand of concrete, significant volume of natural resources is required, including virgin aggregates. Many studies have shown that the production of concrete has one of the highest CO2 levels. Although efforts are in place to recycle, enormous effects on landfill and the wider environment remain. Research has suggested the importance of reusing construction and demolition waste such as aggregate for use in recycled concrete. However, robust construction and demolition waste reduction strategies are required. There have been numerous researches on the use of recycled concrete and its management in the construction industry. This paper further consolidates this position.

Design/methodology/approach

This paper exhibits the barriers and benefits of using recycled aggregates for construction industry. This is achieved via reviewing the current construction and demolition waste reduction strategies used mainly in three countries: the UK, Australia and Japan. These countries were selected since they seemingly have similar construction industry and environment. Subsequently, evolving barriers and benefits of using recycled aggregates for construction industry are also reviewed and discussed. And to support such focus, robust construction and demolition waste reduction strategies will be advocated.

Findings

The findings are summarized as follows. The recycling construction and demolition waste could have a positive net benefit compared to the procurement and production of virgin aggregate materials with the same properties. This is not only financially beneficial but also environmentally viable, as fewer resources would be required to produce the same aggregate material. There are effective ways to achieve a high recycle rate target, as demonstrated by Japan. The implementation of a similar recycling process could be implemented globally to achieve a more effective recycle rate through the help of governments at all levels. By creating awareness about the financial and environmental benefits of using recycled aggregate products, large recycling companies can be also enticed to follow suit.

Practical implications

The findings from this paper can ultimately support the construction industry to further consolidate and advocate the use of recycled aggregates.

Originality/value

To achieve the research aim, this paper reviews some of the main sustainability factors of recycled aggregates (including coarse and fine aggregates) and provides comparison to virgin aggregates.

Details

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

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Article
Publication date: 11 July 2019

Gopalakrishnan Rajagopalan

The durability of concrete structures, especially built-in corrosive environments, starts to deteriorate after 20–30 years, even though they have been designed for more…

Abstract

Purpose

The durability of concrete structures, especially built-in corrosive environments, starts to deteriorate after 20–30 years, even though they have been designed for more than 60 years of service life. The durability of concrete depends on its resistance against a corrosive environment. Inorganic Polymer concrete, or geopolymer concrete, has been emerging as a new engineering material with the potential to form an alternative to conventional concrete for the construction industry. The purpose of this paper is to conduct the investigation on corrosion of the geopolymer materials prepared using GGBS blended with low calcium fly ash in different percentages and sodium hydroxide, sodium silicate as activators and cured in ambient conditions (25±5°C).

Design/methodology/approach

GGBS was replaced by fly ash at different levels from 0 to 50 percent in a constant concentration of 12M. The main parameters of this study are the evaluation of strength characteristics of geopolymer concrete and resistance against corrosion by conducting accelerated corrosion test (Florida method).

Findings

From the test results it is observed that the strength of the geopolymer concrete with GGBS in ambient curing performs well compared to geopolymer concrete with GGBS blended with fly ash. The GPCE sample (40 percent replacement of fly ash to GGBS) shows better results and the resistance against corrosion was good, compared to all other mixes.

Research limitations/implications

The outcomes of this investigation will be useful for the researchers and the construction industry.

Practical implications

This paper results that optimum percentage of fly ash should be blended with GGBS against the corrosion attack. This investigation indicates that GGBS without the combination of fly ash can be utilized in a normal environment. These findings will definitely be useful for the ready-mix concrete manufacturers and the construction Industry.

Social implications

Disposal of industrial wastes causes pollution to the environment. Industrial wastes are utilized for the production of geopolymer concrete, which is the alternative material for the construction industry.

Originality/value

From the observation of the previous literature, till now there was no investigation on geopolymer concrete for corrosion under ambient curing conditions, as such this investigation could be considered as the new investigation.

Details

Engineering, Construction and Architectural Management, vol. 26 no. 8
Type: Research Article
ISSN: 0969-9988

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Article
Publication date: 13 March 2017

Swapnil K. Shirsath and Subhash C. Yaragal

This study reports the performance of thermally deteriorated concrete with and without fibres. Attempts have been made to find the suitable performance of steel…

Abstract

Purpose

This study reports the performance of thermally deteriorated concrete with and without fibres. Attempts have been made to find the suitable performance of steel polypropylene (PP) hybrid fibre combination that could significantly enhance the performance of mechanical properties at elevated temperatures.

Design/methodology/approach

In this experimental investigation, concrete cubes of 100 mm in size of various compositions were cast and water-cured for 28 days, and later exposed to elevated temperatures of either 200 or 400°C or 600 and or 800°C with a retention period of 2 h. The properties like change in colour and percentage weight loss were evaluated. Ultrasonic Pulse Velocity test was used to obtain qualitative information of strength variation. Residual strength of thermally deteriorated concrete specimen was measured by destructive testing.

Findings

Steel fibre volume fraction of 1 per cent improves the compressive strength of concrete in the temperature range of 400 to 800°C. The addition of steel fibre and PP fibre (Mix 3) improves the splitting strength of the concrete at elevated temperature range of 400 to 600°C.

Originality/value

Performance enhancement is observed with hybrid fibres for temperature endurance of concrete.

Details

Journal of Structural Fire Engineering, vol. 8 no. 1
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 25 June 2019

Sachin B.P. and N. Suresh

The present experimental investigation attempts to study the behaviour of hybrid fibre-reinforced self-compacting concrete (HFSCC) subjected to elevated temperature. The…

Abstract

Purpose

The present experimental investigation attempts to study the behaviour of hybrid fibre-reinforced self-compacting concrete (HFSCC) subjected to elevated temperature. The purpose of this study is to find out the performance of hybrid fibres of 0.5 per cent by volume of concrete (out of which 75 per cent are steel fibres and 25 per cent, polypropylene fibres). Reinforced beams were casted and tested for the flexural load-carrying capacity, and comparisons were made with the load-carrying capacity of reinforced beams without the inclusion of fibres.

Design/methodology/approach

The study includes 60 concrete cubes of 150 mm and 60 beams of 150 × 150 × 1,100 mm reinforced with minimum tension reinforcement according to IS 456-2000. The specimens were subjected to elevated temperature from 100°C to 500°C with an interval of 100°C for 2 h. The residual compressive strength and the load-carrying capacity of beams for 5-mm deflection were measured. Parameters such as load at first crack, width and length of cracks developed on the beam during the application of load were also studied.

Findings

The result shows that for self-compacting concrete without fibres (SCCWOF), there is a gain in compressive strength between 200°C and 300°C, beyond which the strength decreases. For HFSCC, the gain in strength is between 300°C and 400°C, and thereafter the strength gets reduced. The load-carrying capacity of beams reduces with an increase in temperature. An increase in load-carrying capacity (up to 40.7 per cent) for HFSCC beams is observed when compared to SCCWOF beams at 500°C.

Originality/value

Better performance was observed with the usage of fibres when the specimens were subjected to elevated temperatures.

Details

Journal of Structural Fire Engineering, vol. 10 no. 3
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 6 August 2018

Mounira Chadli, Mellas Mekki and Bouzidi Mezghiche

Reactive powder concretes (RPCs) are new concretes characterized by a particle diameter not exceeding 600 µm and very high compressive and tensile strengths. This paper…

Abstract

Purpose

Reactive powder concretes (RPCs) are new concretes characterized by a particle diameter not exceeding 600 µm and very high compressive and tensile strengths. This paper aims to the development and study of the physico-mechanical, elastic properties and durability of an ultra-high performance concrete from materials existing on the Algerian market.

Design/methodology/approach

Three mineral additions such as granulated slag, quartz powder and silica fume are incorporated into the cement with 15, 23 and 25 per cent, respectively, in addition to use two different values of steel fiber volume fraction (2 and 2.5 per cent). The results show that the incorporation of 2.5 per cent metal fibers in the formulation of the RPC gives a high compressive strengths of 143.5 MPa at 60 days. The relationship between the relative value and the longitudinal elasto-instantaneous deformations of the RPC to a linear characteristic throughout the relative stress ranges. Also, the modulus of elasticity developed for a fiber-reinforced reactive concrete is greater than that of the unbound fiber.

Findings

Results from the current study concluded that the presence of the mineral additions improves the durability of the concretes compared with that not adjuvanted by mineral additions.

Originality/value

It can be possible to manufacture fiber-reinforced reactive powder concretes (RPCFs) with compressive strength exceeding 140 MPa, with an adequate plasticity, despite the simplicity of means and materials and the incorporation of different percentage of metal fiber on the mechanical strength of concretes and its influence on behavior with respect to aggressive environment were achieved.

Details

World Journal of Engineering, vol. 15 no. 4
Type: Research Article
ISSN: 1708-5284

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