Long-Term Performance of RC Members Externally Strengthened by FRP Exposed to Different Environments

Abstract

Environmental conditions in the Gulf region are considered to be very aggressive to most structures. The main objective of the paper is to study the performance of RC elements (beams and slabs) strengthened by externally bonded FRP using carbon fiber-reinforced polymer (CFRP) sheets and strips and exposed to different environmental conditions. Six exposure conditions were used in the investigation to represent the Gulf region various environments. The exposure conditions used are laboratory, site, high temperature and humidity, cyclic drinking water, cyclic sea water and being embedded in Sabkha soil. The results presented in this paper are a part of a 36-month study program to evaluate the performance of different strengthened RC elements. This paper includes the 18-month test results after exposing the specimens to different environmental conditions. Comparison of the test results with the virgin elements (i.e. at 28 days of age and not exposed to the different environments) is carried out to quantify the change in performance of the elements. The performance of the structural elements is evaluated by measuring various deformations such as deflections, concrete strain, reinforcing steel strain and strain in the CFRP sheets and strips. Also, the mode of failure is reported. It was found that beams and slabs strengthened with CFRP strips were greatly affected by the exposure conditions compared with those strengthened by CFRP sheets. Sabkha soil and sea water were found to be the most aggressive environments.

Experimental Investigation and Modeling of the Thermal Effect on the Mechanical Properties of Polyethylene-Terephthalate FRP Laminates

“…Because retrofitting applications often integrate FRP systems into the external face of weakened structures, FRPs are usually exposed to open and potentially harsh environments (Al-Tamimi et al 2015;El-Dieb et al 2012;El-Hassan and El Maaddawy 2019). Temperature exposure is of particular interest because the utilized polymeric materials generally exhibit strong temperature dependence through their mechanical properties with limited temperature increases (approximately 25°C-75°C) (Hawileh et al 2009(Hawileh et al , 2015a and significant so ft ening beyond their glass transition temperature (T g ) (60°C-110°C) (Ou et al 2016;Reis et al 2012).…”

Recent developments in experimental and computational studies of hygrothermal effects on the bond between FRP and concrete

“…While specimen preconditioning in an environmental chamber before loading has been the traditional approach utilized by many researchers, [85][86][87][88][89] it has been shown that such an approach underestimates the deterioration of FRP-concrete under hygrothermal conditioning. Ren et al 90 coupled FTs with a dead load to study the durability of beams (in flexure) subjected to FT-cycles under a sustained load.…”

Effects of salt solution on mechanical behaviors of aramid fiber–reinforced polymer (AFRP) sheets and AFRP-to-concrete joints

“…In terms of the failure modes, salt fog cycles and immersion in salt water were associated with failure at the interface of concrete and adhesive, differing from failure in the concrete near-surface substrate of the reference beams, regardless of types of strengthening materials. EI-Dieb et al (2012) conducted research on the long-term (6 and 18 months) performance of reinforced concrete beams and slabs externally strengthened by CFRP exposed to sea water or sabkha soil condition. For the sea water exposure, the specimens were exposed to cycles of immersion in the sea water for 2 weeks followed by 2 weeks of natural drying.…”