Introduction

GFRP composite materials are well-known for their high strength-to-weight-ratio and non-corrosive properties. Water facilities and other waterside concrete structures have to withstand severe environment during their life cycle. This is why municipalities and the construction industry spend billions of dollars every year to rehabilitate deteriorated bridges, water treatment plants, and other marine concrete members. The primary cause for the deterioration of the concrete members has been identified as the corrosion of steel reinforcement.

Because GFRP bars are corrosion-resistant, one very attractive area of their application is waterside reinforced concrete structures. This blog post will discuss the case study, “Design and Performance of Reinforced Concrete Water Chlorination Tank Totally Reinforced with GFRP Bars”, and highlight the application of GFRP bars in RC water tanks and wastewater treatment plants (WWTPs).

The project, located in Thetford Mines, Quebec, Canada, is the world’s’ first RC water facility reinforced with GFRP bars. The component of the project reinforced with GFRP bars were the foundation, vertical walls, and cover slabs.

Challenges

RC water tanks have to sustain uniquely different environments in which corrosion poses serious threats. This is why concrete tanks deteriorate faster than any other structure as a result of direct and permanent exposure to aggressive chemical environments. Structural engineers have tried a number of techniques to minimize the intensity of harsh environmental elements on water tanks. The above-mentioned project clearly demonstrated the true potential of GFRP rebar in building corrosion-free concrete members.

Objectives

The objective behind using GFRP bars in this particular project was to eliminate corrosion related issues and build a sustainable and maintenance-free water chlorination tank as it is considered one of the most important components in the city’s new water treatment plant.

Findings

The construction stages of the tank, from foundation and walls to cover slabs, were completed on time and with no precautions about the concrete casting and installation of GFRP rebar. GFRP bars are ¼ the weight of steel. The property of GFRP bars of being lightweight allows engineers to carry out handling and installation of reinforcement with great ease. Construction details, leakage test results, and strain data obtained under conditions concluded that:

• GFRP rebar played a critical role in overcoming the corrosion related problems in the water facility.
• GFRP bars offered ease of installation with no obstacles throughout the water tank’s construction process.
• The performance of water tank was incredible in terms of withstanding applied loads and leakage during the test, while the components of tank reinforced with GFRP bars demonstrated normal performance in terms of cracking and strain during the first 10 months of real service conditions.
• It was the first time GFRP bars were used to construct RC tank for a water treatment plant.
• Excellent in-practice results will encourage the civil engineering community to use GFRP bars increasingly in building water tanks in Canada and across North America.
• GFRP bars extend the life of RC structures to 100 or more years without any major maintenance and repair.

Conclusion

The waterside RC infrastructure has been deteriorating for many years largely due to the inability of steel to withstand harsh environment and heavy loads. The deteriorating water facilities is a large-scale national problem that has been widely reported. Because of their many advantageous characteristics, GFRP bars offer a new and promising solution for a variety of civil construction problems. GFRP’s strengths mesh with the shortcomings of several conventional materials, making advanced composites a material of the 21st Century.