| 1. |
- Ebead, Usama, et al.
(författare)
-
Pull-off characterization of FRCM/Concrete interface
- 2019
-
Ingår i: Composites Part B. - : Elsevier. - 1359-8368 .- 1879-1069. ; 165, s. 545-553
-
Tidskriftsartikel (refereegranskat)abstract
- Fabric-reinforced cementitious matrix (FRCM) composites are usually surface-applied for strengthening reinforced concrete (RC) structures. The efficacy of the FRCM strengthening systems is dependent on the FRCM/concrete bond performance. This paper reports on the experimental results of FRCM/concrete bond characterization through pull-off tests. Six FRCM-strengthened RC slabs (500mm×500mm×100 mm) were prepared and enabled conducting 72 FRCM/concrete pull-off tests. The parameters investigated included: (a) FRCM material (carbon or polyparaphenylene benzobisoxazole (PBO)); (b) level of substrate roughness (no/low/high roughening); and (c) specimen’s test age (7, 28, 56, and 84 days). All FRCM systems were single-plied. The study revealed a significance of the surface preparation and test age of specimens on the FRCM/concrete pull-off strength. High-roughness specimens showed an average of 74% pull-off strength increase compared to those without roughening. Also, specimens tested at Day 84 showed 54% strength increase compared to those tested at Day 7, on average. PBO-FRCM system showed slightly higher pull-off strength than that of the carbon counterpart. The specimens showed two distinctive failure types at the (i) fabric/mortar interface and (ii) concrete/matrix interface: the latter was more prominent in carbon-FRCM. Nonetheless, the failure mode was most dependent on the fabric geometry and the substrate roughness. Based on a statistical analysis of the tested specimens, prediction models were proposed for the FRCM/concrete pull-off strength and failure mode.
|
|
| 2. |
- Shrestha, Kshitij C., et al.
(författare)
-
Effect of surface roughening on concrete/trm bond
- 2017
-
Ingår i: Proceedings of International Structural Engineering and Construction. - : ISEC Press. - 2644-108X. - 9780996043748 ; , s. 1-6
-
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.
|
|
| 3. |
- Younis, Adel, et al.
(författare)
-
A perspective on seawater/frp reinforcement in concrete structures
- 2017
-
Ingår i: ISEC 2017 - 9th International Structural Engineering and Construction Conference. - : ISEC Press. - 2644-108X. ; , s. 1-6
-
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.
|
|
| 4. |
- Younis, Adel, et al.
(författare)
-
A study on the bond behavior of different FRCM systems
- 2018
-
Ingår i: International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018). - : EDP Sciences.
-
Konferensbidrag (refereegranskat)abstract
- Fabric-reinforced cementitous matrix (FRCM) composites are usually applied on the concrete surface for the purpose of strengthening reinforced concrete structures. However, the efficiency of FRCM strengthening is notably affected by the bond between the FRCM system and concrete substrate. In view of that, the current paper presents the results of a preliminary experimental study carried out to investigate the bond characteristics between FRCM composites and concrete. Six number of specimens, each consisted of a 150-mm concrete cube with a double-shear connection to an FRCM system, were subjected to direct-shear loading test. The parameters investigated include (a) FRCM material (carbon, polyparaphenylene benzobisoxazole (PBO), and glass); and (b) Bond length (75 mm or 100 mm). The FRCM systems typically included a single layer of fabric with the associated mortar, and the bond width was uniformly taken as 100 mm. The test results revealed that the bond capacity is enhanced with an increase in the FRCM bonded length. The PBO-FRCM showed the highest bond capacity between FRCM composite and concrete substrate among the three systems. The modes of failure observed in carbon-, PBO-, and glass-FRCM bond tests are fabric delamination, FRCM mortar/concrete debonding, and fabric rapture, respectively. The PBOand glass-FRCM bond tests thus exhibited a more brittle behavior at failure than that of the carbon-FRCM counterpart.
|
|
| 5. |
- Younis, Adel, et al.
(författare)
-
Bond and shear-strengthening performance of FRCM composites
- 2019
-
Ingår i: Proceedings of International Structural Engineering and Construction. - : ISEC Press. - 2644-108X. - 9780996043762 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- This paper is aimed at studying the bond and shear-strengthening performance of fabric reinforced cementitious matrix (FRCM) systems. Three FRCM systems were compared, namely, polyparaphenylene benzobisoxazole (PBO)-FRCM, Carbon-FRCM, and Glass-FRCM. At first, six double-shear specimens were tested to investigate the FRCM/concrete bond, with the test variables including the fabric type and the bond length. After that, seven shear-critical reinforced concrete (RC) beams were tested under three-point loading, considering the fabric type and strengthening configuration (full/intermittent) as the test variables. As for the double-shear test results, the failure observed was fabric/matrix debonding in carbon-FRCM, matrix/concrete debonding in PBO-FRCM, and fabric rapture in glass-FRCM. The FRCM/concrete bond increased with the bonded length, and the PBO-FRCM showed the highest bond to concrete. Regarding the RC beam tests, the FRCM-strengthened beams showed the same failure mode that is debonding at the FRCM/concrete interface. Nonetheless, FRCM had successfully strengthened the beams in shear: an average gain of 57% in the load carrying capacity was achieved as compared to the non-strengthened reference. Indeed, the full-length strengthening resulted in a better structural improvement compared to the intermittent-strengthening configuration. Amongst the three systems, carbon-FRCM systems were the most efficient in shear-strengthening RC beams.
|
|
| 6. |
- Younis, Adel, et al.
(författare)
-
Bond characteristics of different FRCM systems
- 2018
-
Ingår i: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 175, s. 610-620
-
Tidskriftsartikel (refereegranskat)abstract
- Fabric-reinforced cementitious matrix (FRCM) composites are usually applied on the concrete surface for the purpose of strengthening reinforced concrete structures. The efficiency of FRCM as a strengthening material is notably affected by the bond between the FRCM and concrete. In view of that, this paper reports on the results of an experimental study to investigate the bond characteristics between FRCM and concrete. Eighteen specimens with different lengths were prepared and subjected to double-shear test. The parameters investigated included (a) fabric type (carbon, polyparaphenylene benzobisoxazole (PBO), and glass); (b) bond length (75, 100, 125, 150, and 200 mm); and (c) number of fabric plies (single or double). The modes of failure observed in carbon-, PBO-, and glass-FRCM bond tests are fabric/matrix debonding, FRCM mortar/concrete debonding, and fabric rapture, respectively. The PBO- and glass-FRCM bond failure was more brittle than that of the carbon-FRCM counterpart. Among the three systems, the PBO-FRCM showed the highest FRCM/concrete bond. The bond capacity and the mode of failure were prone to the number of fabric plies and indeed bond length. Theoretically-predicted values for the FRCM bond capacity were obtained based on a proposed analytical model, and showed a reasonable agreement with the experimental results.
|
|
| 7. |
- Younis, Adel, et al.
(författare)
-
Characterization and application of FRCM as a strengthening material for shear-critical RC beams
- 2018
-
Ingår i: International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018). - : EDP Sciences. ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the effectiveness of fabric reinforced cementitious matrix (FRCM) systems in shear-strengthening of reinforced concrete beams. Three types of FRCM systems were considered, namely, polyparaphenylene benzobisoxazole (PBO)-FRCM, Carbon-FRCM, and Glass-FRCM. At first, tensile characterization test was performed on 15 FRCM coupons with the aim of identifying the tensile properties of the FRCM systems adopted. After that, seven shear-critical RC beams were tested under three-point loading, with the consideration of two test parameters: (a) FRCM material (glass/carbon/PBO); and (b) strengthening configuration (full/intermittent). The study results revealed the use of FRCM as a strengthening material to achieve a considerable improvement in the structural capacity of shear-critical RC beams. The average gain in the shear capacity of the FRCM-strengthened beams was 57%. The beam specimens strengthened with carbon-FRCM showed the highest improvement as compared to those strengthened with glass-and PBO-FRCM systems. As intuitively expected, the shear capacity improvement achieved with the full-length strengthening systems was generally higher than that with the intermittent counterparts.
|
|
| 8. |
- Younis, Adel, et al.
(författare)
-
Cost effectiveness of reinforcement alternatives for a concrete water chlorination tank
- 2020
-
Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 27, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- Reinforced concrete tanks in water/wastewater treatment plants are susceptible to severe corrosion due to aggressive exposure conditions resulting from the application of certain treatment chemicals and methods. Non-corrosive materials, such as stainless steel or fiber reinforced polymer (FRP), may be attractive alternative reinforcement options for such concrete structures. However, the high initial cost of such materials imposes constraints on their use, although such thinking ignores improvements in long-term concrete durability. The current paper addresses the use of non-corrosive reinforcement in a concrete water chlorination tank using life-cycle cost analysis (LCCA) that aims to evaluate the cost effectiveness of different reinforcement alternatives. A comparison was established between four concrete reinforcing materials, namely, black steel, epoxy coated steel, stainless steel, and glass-FRP (GFRP) through a 100-year analysis period. The results of this study suggest that the use of non-corrosive reinforcement helps achieve a considerable long-term cost saving. LCCA showed that GFRP becomes more economical than black steel in 35 years following construction. The net present cost (NPC) obtained for the GFRP-reinforced concrete was approximately 43% lower than that of the black steel reinforced concrete. The use of stainless steel also had a potential advantage but was less cost-effective than GFRP, with a 50-year payback period and an NPC 25% lower than that of the conventional design. Epoxy coated steel also showed a long-term cost benefit when compared to black steel, with approximately 11% reduction in NPC and 15-year extension in the service life. Sensitivity analyses were performed to assess the effects of the analysis period, discount rate, construction costs, concrete strength, and the use of supplementary cementitious materials on the LCCA outcomes.
|
|
| 9. |
- Younis, Adel, et al.
(författare)
-
Different FRCM systems for shear-strengthening of reinforced concrete beams
- 2017
-
Ingår i: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 153, s. 514-526
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of an extensive experimental study on the efficacy of different fabric-reinforced cementitous matrix (FRCM) systems for the strengthening of reinforced concrete (RC) beams, which are critical in shear. Three types of FRCM systems were assessed; namely, Carbon–FRCM, polyparaphenylene benzobisoxazole (PBO)-FRCM, and Glass–FRCM. Tensile characterization tests were carried out on fifteen (15) FRCM coupons with the purpose of identifying the tensile properties of the FRCM systems. In the core part of this study, sixteen (16) shear-critical RC beam specimens were tested under three-point loading for assessing the effect of FRCM stiffness/type, FRCM configuration, and FRCM anchorage on the load and deformational capacities of the strengthened beams. As for the study results, the average enhancement of the load carrying capacity achieved by FRCM strengthening with respect to the reference specimen is 51%. Continuous strengthening significantly improved all aspects of structural performance of the strengthened beams compared to those of the intermittent counterpart. The effect of FRCM configuration appeared to be significantly related to the amount and the orientation of the effectual fabric within the FRCM system. Moreover, the effect of the FRCM anchorage used in this study was observed to be insignificant on the load carrying capacity of the strengthened beams. Theoretically-predicted values for load carrying capacity were obtained, and showed a reasonable agreement with the experimental results.
|
|
| 10. |
- Younis, Adel, et al.
(författare)
-
FRCM shear strengthening for concrete beams
- 2017
-
Ingår i: ISEC 2017 - 9th International Structural Engineering and Construction Conference. - : ISEC Press. - 2644-108X. - 9780996043748
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental study carried out to examine the efficacy of Fabric-Reinforced Cementitious Matrix (FRCM) in strengthening RC beams susceptible to shear failure. In this paper, seven shear-critical RC beams, of 2,500 mm in length, 150 mm in width, and 330 mm in depth, were tested under three-point loading until failure. Two main test variables were considered, which are: A) Strengthening material: carbon, polyparaphenylene benzobisoxazole (PBO), or glass FRCM, and b) Strengthening application pattern: A single full-length FRCM plate or a set of intermittent and spaced FRCM strips were applied along the critical shear zone. The test results confirmed the efficacy of FRCM strengthening in improving the load capacity of shear-critical RC beams. The FRCM-strengthening contributed to increases in the load capacity ranged between 31% and 100% compared to the reference specimen. The full-length strengthened specimens generally showed a better strength enhancement compared to the intermittent counterparts when using the same FRCM material. Such intuitive observation assures the importance of the amount of strengthening material applied in the critical shear zone. Besides, specimens utilizing carbon fibers in its FRCM strengthening material showed the highest strength enhancement among the three systems.
|
|
