| 1. |
- Hamid, S., et al.
(författare)
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Material performance and cost effectiveness of seawater-mixed rubberized concrete
- 2021
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Ingår i: Case Studies in Construction Materials. - : Elsevier BV. - 2214-5095. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- The combined use of seawater and recycled tire aggregate (RTA) in concrete is potentially a way forward towards sustainable construction. It can help control harvesting of natural aggregates, manage waste tires, mitigate freshwater consumption and desalinationimpacts. The current paper aims at investigating the material performance and cost effectiveness of concrete mixed with seawater and RTA. The paper consists of two parts. The first part studies the characteristics (fresh and hardened) of concrete mixed with seawater and RTA. Thirteen concrete mixtures, varying in mixing water (seawater/freshwater) as well as fine and coarse aggregates (at 0%, 5%, 10%, and 20% replacement levels), were investigated. An extensive experimental program was conducted to compare the thirteen mixtures in terms of physical properties, workability, strength, water absorption, and chloride permeability. The second part of the paper performs a life cycle cost analysis (LCCA) for a 20-story building over a 100-year analysis period to verify the cost effectiveness of a proposed sustainable concrete that combines seawater, RTA (at 5% replacement level), and glass fiber-reinforced polymer (GFRP) reinforcement. A sensitivity analysis was performed to investigate the effect of the discount rate on the LCCA results.
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| 2. |
- Shrestha, K. C., et al.
(författare)
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Effect of Surface Roughening on Concrete/TRM Bond
- 2017
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Ingår i: Proceedings of International Structural Engineering and Construction.
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Konferensbidrag (refereegranskat)abstract
- Textile reinforced mortar (TRM) is applied on the concrete surface with the aim of strengthening reinforced concrete structures. The performance of the strengthened structural system is directly related to the bond between the existing concrete substrate and the freshly applied TRM layer. This paper presents the results of an experimental study carried out to investigate the significance of concrete surface preparation, performed prior to strengthening, on the bonding behavior of the TRM system. For this purpose, concrete slabs of size (500 mm × 500 mm × 100 mm) were prepared and strengthened using a 10-mm thick TRM layer. After that, the bond performance of the strengthening layer with the concrete slab was assessed using the pull-off test. Three different levels of surface roughening were considered before strengthening: (i) no roughening (regarded as the reference), (ii) low roughening level, and (iii) high roughening level. Two types of textile materials are used in strengthening systems: carbon and polyparaphenylene benzobisoxazole (PBO). A total number of 72 pull-off tests were performed, of which the results were analyzed to examine the significance of the test variables. Results revealed that as the concrete surface is more roughened before strengthening, the bond between concrete substrate and TRM layer becomes stronger. Moreover, the PBO-TRM systems exhibit more desirable bonding behavior compared to the carbon-TRM counterpart.
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| 3. |
- Younis, Adel, 1990-, et al.
(författare)
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A Perspective on Seawater/FRP Reinforcement in Concrete Structures
- 2017
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Ingår i: Resilient Structures and Sustainable Construction. - 9780996043748
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Konferensbidrag (refereegranskat)abstract
- Predictions show that more than half of the world population will lack sufficient freshwater by 2025. Yet, the construction industry uses a considerable amount of freshwater to produce concrete. To save resources of fresh water, using seawater seems to be a valid potential alternative that can replace freshwater for mixing concrete. This paper presents a short review performed on existing literature related to the usage of seawater in concrete structures. As a summary of the work presented: (a) It is noticeable that the current literature, generally, reports little or no negative effect of seawater on the characteristics of plain concrete, both in the short and in the long term; (b) steel corrosion caused by the presence of chloride appears to be the sole reason for not accepting the use of seawater in concrete preparation; (c) Fiber reinforced polymer (FRP) is discussed as a promising alternative to steel for seawater- concrete reinforcement, owing to their light weight, high tensile strength, and adequate corrosion resistance; and (d) A future outlook for using seawater accompanied by FRP reinforcement in concrete structures is discussed in terms of achieving sustainability goals.
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| 4. |
- Younis, Adel, 1990-, et al.
(författare)
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Effect of using multiple fabric plies on the tensile behaviour of carbon textile reinforced mortar
- 2020
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Ingår i: Proceedings of the 8th Euro-American Congress (REHABEND 2020). ; , s. 2255-2261
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Konferensbidrag (refereegranskat)abstract
- Recently, textile reinforced mortar (TRM) has emerged as a viable strengthening material for reinforced concrete (RC) and masonry structures. Understanding the TRM tensile behaviour is important to achieve an accurate design for TRM strengthening systems. This paper investigates the tensile properties of carbon-TRM composite with multiple fabric plies. Twenty TRM specimens (410 × 50 mm), which varied in the number of fabric plies (one/two/three/four), were prepared and tested in accordance with AC 434 provisions (clevis-grip mechanism). The results revealed a significance of the number of fabric plies on the tensile capacity as well as the failure behaviour of the TRM composite. The failure mode had changed from ductile fabric slippage (associated with up to 3 fabric plies) to brittle fabric delamination in carbon-TRM specimens when using 4 layers of fabric. As expected, the TRM tensile capacity had proportionally increased with the number of fabric plies. The effect of the number of fabric plies was less significant (within 20%), though, on the ultimate tensile stresses of the impregnated fabric. The results verified the established bilinear trend for TRM tensile stress-strain relationship that indicates two sequential phases, namely, noncracked/stiff and cracked-section phases. However, the TRM cracked tensile modulus had somewhat increased with an increase in the number of fabric plies. © 2020, University of Cantabria - Building Technology R&D Group. All rights reserved.
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| 5. |
- Younis, Adel, 1990-, et al.
(författare)
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Effects of Using Seawater and Recycled Coarse Aggregates on Plain Concrete Characteristics
- 2020
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Ingår i: International Conference on Civil Infrastructure and Construction (CIC 2020). - : Qatar University Press. ; , s. 794-800, s. 794-800
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Konferensbidrag (refereegranskat)abstract
- Using seawater and/or recycled coarse aggregates (RCA) for concrete mixing is deemed advantageous from a sustainability perspective. This paper reports on the results of an experimental study on fresh and hardened properties of concrete mixed with seawater and RCA. Three concrete mixtures were investigated, namely, Mix A (traditional concrete), Mix B (concrete made with seawater), and Mix C (concrete made with seawater and RCA). It was concluded that the use of seawater and/or RCA had a notable effect on fresh concrete properties. Mix B concrete showed a slightly lower strength performance than that of Mix A (<15%), whereas the strength of Mix C concrete had a significant drop (~30%) compared to the reference (Mix A). The permeability performance of hardened concrete for Mixes A and B was similar, whereas Mix C concrete showed 60% increase in water absorption and 100% increase in chloride permeability as compared to Mix A.
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| 6. |
- Younis, Adel, 1990-, et al.
(författare)
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Long-Term Cost Performance of Corrosion-Resistant Reinforcements in Structural Concrete
- 2020
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Ingår i: International Conference on Civil Infrastructure and Construction (CIC 2020). - : Qatar University Press. ; , s. 801-805, s. 801-805
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Konferensbidrag (refereegranskat)abstract
- Corrosion, which leads to the premature deterioration of reinforced concrete (RC) structures, is increasingly an issue of global concern. Accordingly, corrosion-resistant materials have emerged as alternative reinforcement solutions in concrete structures. Yet, the high initial cost of such materials may mitigate their potential use. This paper reports on the results of two life-cycle-cost-analysis (LCCA) studies that aim at verifying the long-term cost performance of corrosion-resistant reinforcements in structural concrete. The first study conducted a 100-year-based LCCA study to evaluate the relative cost savings of structural concrete that combines seawater, recycled coarse aggregates, and glass fiber-reinforced polymer (GFRP) reinforcement in high-rise buildings as compared to a traditional reinforced concrete (i.e., freshwater-mixed, natural-aggregate, black-steel- reinforced). In the second study, a life-cycle-cost comparison was established among four reinforcement alternatives, viz., conventional steel, epoxy-coated steel, stainless steel, and GFRP for a RC water chlorination tank considering a 100-year study period. The results of these two studies suggest that the use of corrosion-resistant reinforcement (especially GFRP) in structural concrete may potentially lead to significant cost savings in the long term: the net present cost of GFRP-RC structures was generally 40–50% lower than that reinforced with black steel.
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| 7. |
- Younis, Adel, 1990-, et al.
(författare)
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Shear strength of recycled-aggregate concrete beams with glass-FRP stirrups
- 2022
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Ingår i: Composites Part C: Open Access. - : Elsevier BV. - 2666-6820. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The combined use of recycled concrete aggregate (RCA) and glass fiber reinforced polymer (GFRP) reinforcement in reinforced concrete (RC) structures is deemed plausible to achieve sustainable construction. This paper aims to examine the effect of such a combination (RCA + GFRP reinforcement) on the shear behavior of RC beams. Six medium-scale RC beams (150 × 260 × 2200 mm) critical in shear were tested under three-point loading until failure. The test variables were the aggregate type (natural/recycled) and the shear reinforcement (steel/GFRP/none). The failure modes, cracking patterns, load-carrying capacities, deformational and strain characteristics were analyzed and compared among the tested specimens. It was found that using 100% RCA in the concrete mix reduced the shear strength of RC beams (by 12% on average). Minor effects were observed on the shear strength of the beam specimens (∼2%) with altering the transverse reinforcement (GFRP versus steel). Theoretical load-carrying capacities of the tested beams were obtained as per contemporary design guides and compared with the experimental results.
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