Durability of GFRP reinforcement in seawater concrete - Part I

Corrosion Science, 2018

Highlights  A large number of FRP tensile specimens were tested after exposure to SWSSC corrosive solution  Coupling of stress, corrosion and temperature significantly accelerates the degradation of FRP bars

Construction and Building Materials, 2017

Strength tests on BFRP/GFRP bars in seawater and sea sand concrete (SWSSC) environment. GFRP bars are more durable than BFRP bars in SWSSC environment. No change in Young's modulus for GFRP and BFRP bars after exposure in SWSSC solutions. Current models are conservative in predicting long-term strength of BFRP/GFRP bars.

Materials and Structures

The lower bond strength of FRP bars to concrete compared to steel bars has remained an unsolved barrier to the widespread use of FRP-reinforced concrete under extreme loading. Additionally, the degradation of the bond between FRP reinforcement and concretes in aggressive environments adds to the existing concern. In this study, an innovative anchorage system comprised of polypropylene pipe was used to strengthen the bond between seawater concrete and GFRP bars after 250 days of exposure to offshore environmental conditions. As material factors, two types of GFRP bars (sand-coated and ribbed) and two types of concrete (normal and seawater concrete) were evaluated. Four distinct environmental conditions were used to assess the samples: (i) ambient environment (control), (ii) tap water, (iii) seawater, and (iv) wet-dry cycles in seawater. According to the findings of the direct pull-out tests, the suggested anchor system strengthens the bond and shifts the failure mode from bond failur...

Construction and Building Materials, 2017

h i g h l i g h t s Shear strength tests on FRP bars in seawater and sea sand concrete (SWSSC) environment. Moisture absorption and desorption tests were carried out for BFRP/GFRP/CFRP bars. SEM images and FTIR spectroscopy were used to explain failure mechanism. Current models are conservative in predicting long-term strength of BFRP/GFRP/CFRP bars.

IOP Conference Series: Earth and Environmental Science

In Mediterranean countries seawater might become a resource for the concrete production for sustainable construction industry. Nowadays its use, since it might induce the corrosion on ordinary carbon steel bars, is prohibited for the realization of reinforced concrete structures. Within the SeaCon Project, the use of seawater as mixing water has been studied in combination with corrosion-resistant reinforcement. This paper, firstly, discusses the influence of chlorides present in the seawater on the concrete properties related to the durability. Afterwards, the corrosion resistance of austenitic (304L and XM-28) and duplex (23-04 and 22-05) stainless steels reinforcing bars, and for comparison of carbon steel, embedded in alkaline and carbonated concretes made with seawater and subjected to different environmental conditions is evaluated. Results showed that seawater accelerated the early strength of concrete, whilst the carbonation penetration, the capillary suction and water absorption were slightly affected. Corrosion tests showed that corrosion did not initiate on 304L, 23-04 and 22-05 stainless steel bars, despite the presence of chlorides since the beginning even in the most aggressive exposure conditions and when concrete was carbonated; XM-28 reinforcement showed a slight change in corrosion behaviour in carbonated concrete exposed to the harshest conditions.

Journal of Composite Materials, 2019

Conventional concrete suffers from brittle failures under mechanical behaviour, and lack of ductility results in the loss of human life and property in earthquake zones. Therefore, the degree of ductility becomes significant in seismic regions. This paper investigates the influence of poly-vinyl alcohol fibers, basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) fabrics on the ductility and mechanical performance of low (LCFA) and high (HCFA) calcium fly ash-based engineered cementitious composite concrete. The study also focuses on the mechanical behaviour of the CFRP and BFRP materials using different matrix types exposed to 3.5% seawater environment. Cyclic loading and scanning electron microscopy observations were also performed to see the effect of chloride attack on mechanical performance and ductility of the specimens. In addition, utilization of CFRP and BFRP fabrics as a retrofit material is also evaluated. Results indicated that the degree of ...

Construction and Building Materials, 2020

h i g h l i g h t s 70 Pullout bond tests with GFRP bars in conventional or seawater-mixed concrete. Detailed comparison of peak bond strength and bond-slip response. One-way ANOVA tests were conducted to compare the results. No statistically significant reduction in bond strength using seawater concrete.

2017

Although glass fibre reinforced polymer (GFRP) bars do not corrode in the same way as conventional steel reinforcement, their physical and mechanical properties are prone to degradation following exposure to a variety of aggressive environments. Despite the relatively large amount of research on durability of FRP reinforcement in concrete environments, the available design models are still not able to account for all of the most typical in-service conditions, especially the effect of sustained stress on long-term properties. Thus, there is a need to develop a reliable prediction model to estimate the rate of degradation of GFRP bars and long-term performance in real structural applications. A comprehensive test programme was carried out on 348 GFRP specimens subjected to different environments (concrete, alkali solution and tap water), different temperature levels (20, 40, 60°C) and two different levels of sustained stress. The mechanical performance of the GFRP specimens, as well a...

Materials

Fiber-reinforced polymer (FRP) composites have gained increasing recognition and application in the field of civil engineering in recent decades due to their notable mechanical properties and chemical resistance. However, FRP composites may also be affected by harsh environmental conditions (e.g., water, alkaline solutions, saline solutions, elevated temperature) and exhibit mechanical phenomena (e.g., creep rupture, fatigue, shrinkage) that could affect the performance of the FRP reinforced/strengthened concrete (FRP-RSC) elements. This paper presents the current state-of-the-art on the key environmental and mechanical conditions affecting the durability and mechanical properties of the main FRP composites used in reinforced concrete (RC) structures (i.e., Glass/vinyl-ester FRP bars and Carbon/epoxy FRP fabrics for internal and external application, respectively). The most likely sources and their effects on the physical/mechanical properties of FRP composites are highlighted herei...

Advances in Structural Engineering, 2019

In the study, mechanical properties and durability performance of confined/unconfined geopolymer concrete and ordinary concrete specimens were investigated under ambient and seawater environments. Some of the specimens were confined by carbon fiber and basalt fiber–reinforced polymer fabric materials with one layer and three layers under chloride and ambient environments to observe mechanical strength contribution and durability performances of these hybrid types of materials. These fiber-reinforced polymer fabric materials were also evaluated in terms of retrofit purposes especially in the marine structures. In addition, microstructural evaluation is also conducted using scanning electron microscope on geopolymer concrete and ordinary concrete specimens to observe the amount of deterioration in microscale due to the chloride attacks. Results indicated that confined specimens exhibited enhanced strength, ductility, and durability properties than unconfined specimens, and the degree ...