Abstract:
Due to their excellent mechanical properties and easy application Carbon Fibre
Reinforced Polymers (CFRP) are being successfully used to repair and renewing old
and damaged civil engineering infrastructures. In particular, the method of
strengthening concrete members with externally bonding of CFRP laminates has
become increasingly popular. In fact, extensive research has shown that this technique
can lead to a substantial improvement in the flexural and shear strength capacities of
the member repaired. In such applications, materials involved will be exposed to
outdoor environmental conditions, including humidity, water from rain, saline-water,
ground water and high alkalinity solutions due to chemical composition of the concrete
itself, as well as solar ultraviolet radiation. Thus, it is of great relevancy to study the
durability of the materials involved, namely epoxy adhesives and CFRP laminates, as
well as, the integrity of the entire system, when subjected to those environmental
factors.
This work is part of a much larger research study that is being made to predict the longterm
behaviour of several commercial CFRP laminate/adhesive systems used in the
rehabilitation of concrete structures. In the whole project it is recognized that the
durability of these solutions depends, not only on the durability of the composite
materials but also on the performance of the systems used to bond them to the
concrete. The present document provides details about the part of the investigation
concerning the durability of CFRP laminates.
This paper describes the study carried out to investigate the environmental and
accelerated ageing effects on three types of commercially available CFRP laminates.
The changes in CFRP laminates properties after exposure up to 18 months under
different environmental conditions - immersion in demineralised water, saline and
alkaline solutions at room temperature, 40 ºC and 60 ºC, as well as under constant
humidity condensation atmosphere at 40 ºC – are reported and discussed. The results
of tests performed in accelerated weathering chambers – with ultraviolet radiation – are
also included.
Results obtained offer valuable information about the progression of material
degradation under different ageing conditions (some of them accelerated), which can
be used, not only to characterize the behaviour of CFRP laminates, but also for a better
understanding of the degradation mechanisms involved, which is a base for the design
of service life-prediction models.
