JEC COMPOSITES MAGAZINE - Issue #106 - July 2016 - 46

review

Ageing of fibre-reinforced polymers
for construction applications
The use of fibre-reinforced polymer (FRP) composites in construction has proved to be an effective solution to repair and/or upgrade existing
buildings or infrastructure systems. While the
technical and economic advantages of using FRP
materials to strengthen and upgrade buildings
and bridges are universally recognized, there are
still serious concerns about the durability of such
materials, which considerably differ from the parent systems used in aerospace and automotive
applications.

By
PROF. MARIAENRICA FRIGIONE, PHD
ASSOCIATE PROFESSOR IN MATERIAL SCIENCE AND TECHNOLOGY,
UNIVERSITY OF SALENTO

T

he recent and enthusiastic introduction of fibre-reinforced
polymers (FRP) as a reinforcement for buildings - to
restore and renew the built infrastructures or to improve
the strength and/or the stiffness of structural elements under
different loading conditions - results from a favourable combination of suitable properties and manufacturing/installation
capabilities. Compared to traditional building materials such as
steel and concrete, polymer composites offer a high strength/
weight ratio, good resistance to fatigue, excellent chemical and
corrosion resistance, ease of installation and cost-effectiveness.
A wider choice of materials is available and product anisotropy
can be tailored to any specific application. However, since the
use of composite reinforcements in infrastructures is a relatively
novel repair method, information on the long-term behaviour/
performance of FRP subjected to weathering, the so-called "durability", is still scarce. Environmental factors can have a crucial
effect on the performance of FRP in service. The existing data

46 jec composites magazine / No106 July 2016

on the durability of these materials in this specific field are not
well documented and often contradictory. The environmental
conditions that the materials can encounter during their application and service life are neither constant nor predictable and
depend on several parameters such as the latitude, the season,
the distance from sea, the local weather, etc. This hampers
the enormous potential of composites in structural building
construction applications, since the acceptable lifetime of the
products employed in this field should be in the order of 50-100
years [Uomoto, 2003; Karbhari, 2005].

Peculiarities of the FRP materials
used in construction
It is generally accepted that polymer composites are very
durable materials, particularly those designed for aeronautical
applications. However, the FRP materials used in civil engineering applications significantly differ from those developed in the
aerospace industry during the past 40 years.
Generally speaking, the durability of FRP composites depends
on the chemical nature of the base materials, on the conditions
in which the matrix resin sets and hardens, on the process used
to manufacture and to apply the composite, and on the in-service environmental conditions. FRP materials are composed
of polymeric thermosetting resins (mainly epoxy but also vinyl
ester and polyester resins) and
fibres. The fibres most commonly used in FRP for structural
reinforcement are based on
carbon, glass or aramid. But the
main differences from the parent
high-performance FRP systems
employed in the more demanding aerospace and automotive
industries arise when comparing
the fabrication procedures. In
the construction industry, they
are closely related to the specific application, involving large
surfaces to be strengthened by an
FRP often formed in the field (i.e.
in situ), without the possibility to
effectively control the manufactu- Preparation of carbon-based fabric
wet lay-up applications. (Photo
ring and processing procedures as for
kindly supplied by SIKA ITALIA
well as the environmental
Company, Italy)
Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #106 - July 2016
