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International Concrete Abstracts Portal

Showing 1-5 of 26 Abstracts search results

Document: 

23-311

Date: 

September 1, 2024

Author(s):

Sathya Thukkaram and Arun Kumar Ammasi

Publication:

Materials Journal

Volume:

121

Issue:

5

Abstract:

Lightweight concrete (LWC) finds wide-ranging applications inthe construction industry due to its reduced dead load, good fireresistance, and low thermal and acoustic conductivity. Lightweightgeopolymer concrete (LWGC) is an emerging type ofconcrete that is garnering attention in the construction industryfor its sustainable and eco-friendly properties. LWGC is producedusing geopolymer binders instead of cement, thereby reducing thecarbon footprint associated with conventional concrete production.However, the absence of standard codes for geopolymer concreterestricts its widespread application. To address this limitation,an investigation focused on developing a new mixture design forLWGC by modifying the existing ACI 211.2-98 provisions has beencarried out. In this study, crucial parameters of LWGC, such asalkaline-binder ratio (A/B), molarity, silicate/hydroxide ratio, andcuring temperature, were established using machine learning techniques. As a result, a simple and efficient method for determining the mixture proportions for LWGC has been proposed.

DOI:

10.14359/51742040


Document: 

21-077

Date: 

September 1, 2022

Author(s):

Abbas Rezaeian, Amir Daghari, and Venkatesh Kodur

Publication:

Materials Journal

Volume:

119

Issue:

5

Abstract:

This paper presents the results of an experimental study on the comparative response of polypropylene (PP) fiber-incorporated reinforced concrete (RC) beams under fire conditions. Five fullscale RC beam specimens, made with different batch mixtures comprising normal plain concrete (NPC) and fiber-reinforced concrete (FRC), were tested to assess their spalling performance and structural behavior under fire conditions. The main variables in the experiments were the amount and length of PP fibers. Deflections, temperatures, and spalling in the beams were monitored during fire exposure. FRC beams’ flexural failure occurs after 151 minutes at heating temperatures beyond 850°C, when deflections exceed span/20. When the concrete contains PP fibers (that is, FRC beams), the gamut of fire-induced spalling in RC beams gets reduced, increasing the fire resistance from 147 to 171 minutes (approximately 17%). Furthermore, test results show that adding 2 to 3 kg/m3 of PP fibers effectively releases the pore pressure through tensile cracking and reduces the amount of spalling in the FRC beams.

DOI:

10.14359/51735947


Document: 

21-360

Date: 

September 1, 2022

Author(s):

F. Dabbaghi, A. Tanhadoust, M. L. Nehdi, M. Dehestani, H. Yousefpour, and H.-T. Thai

Publication:

Materials Journal

Volume:

119

Issue:

5

Abstract:

Structural lightweight-aggregate concrete (LWAC) has gained a broad range of applications in the construction industry owing to its reduced dead load and enhanced fire resistance. In this study, the potential of using lightweight expanded clay aggregates as a partial replacement for fine and coarse natural aggregates was experimentally and numerically examined. Testing was performed on cylindrical specimens made of normalweight and lightweight concrete incorporating microsilica as a partial replacement for cement to determine the associated stress-strain behavior. Subsequently, three-point bending testing was conducted on reinforced concrete beams to evaluate their structural behavior. Four levels of temperature were considered: 25°C (ambient temperature), and 250, 500, and 750°C (elevated temperatures). The finite element method through Abaqus software was deployed to numerically investigate the behavior at elevated temperatures through a comprehensive parametric study. The experimental and numerical results indicate that under high-temperature exposure, LWAC outperforms its normal counterpart in terms of strength, stiffness, and Young’s modulus. It is also noticeable that LWAC beams retained their load-bearing capacity better than normal weight aggregate concrete (NWAC) after reaching the peak load.

DOI:

10.14359/51736093


Document: 

21-029

Date: 

September 1, 2021

Author(s):

Camila Simonetti, Bernardo Fonseca Tutikian, and Luiz Carlos Pinto da Silva Filho

Publication:

Materials Journal

Volume:

118

Issue:

5

Abstract:

The possibility of incorporating scrap tire residue into concrete has already been consolidated in previous studies, but there is a knowledge gap about how concrete made with recycled tire materials behaves when exposed to high temperatures. This study aims to investigate the performance of precast concrete panels made with scrap tire residues when exposed to fire when using recycled steel fiber and recycled rubber aggregates separately. The experimental design consisted of fire resistance tests. Real-scale panels were exposed to the standard fire curve based on ISO 834, measuring the temperatures on the panel surfaces. The recycled steel fiber-reinforced concrete and those containing 5% recycled rubber aggregate presented similar behavior when compared to the conventional concrete on thermal insulation, integrity, and structural stability. The concrete made with 10% recycled rubber aggregate registered the occurrence of explosive spalling and worse thermal insulation and integrity.

DOI:

10.14359/51732983


Document: 

19-080

Date: 

March 1, 2020

Author(s):

Kangkang Tang

Publication:

Materials Journal

Volume:

117

Issue:

2

Abstract:

Steel fiber-reinforced concrete (SFRC) can be an ideal substitute for conventional steel reinforcement in railway tunnel lining construction due to its high strength and good fire resistance. On the other hand, it is still not clear whether discontinuous steel fibers can pick up and transfer stray current and lead to similar corrosive attack as that occurs in conventional steel reinforcement. These were evaluated through voltammetry tests and electrochemical impedance spectroscopy (EIS) before and after simulated railway stray direct current (DC) and alternating current (AC) interferences. In addition to instrumental methods in electrochemistry, numerical modeling based on the boundary element method (BEM) modeling indicates that discrete steel fibers can pick up and transfer stray currents. This was validated by the electrochemical investigations conducted using both aqueous and solid (mortar) electrolytes. It can be concluded that steel fibers have high corrosion resistance to stray AC and DC interferences even with the presence of a small amount of NaCl in the electrolyte.

DOI:

10.14359/51720303


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