JEC COMPOSITES MAGAZINE - Issue #106 - July 2016 - 56

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dimensional tolerance, surface finish
and ease of moulding, resin infusion
was selected as the preferred process for
the floors. ACCIONA developed the
process of infusing 20cm thick floors. As
manufacturing needed to be fast, a resin
system with low viscosity, long pot life
and low exotherm, which was also capable
of meeting the desired chemical and
mechanical properties, was developed by
Huntsman Advanced Materials.

Optimising processes
In order to achieve low weight, low maintenance, a smooth surface, chemical resistance
and aesthetics, metal fasteners were not a
preferred solution to join the pultruded
CFRP tubes with the GFRP tubes. A new
system needed to be designed that could
not only meet the criteria but also should
meet the complex structural and geometric
requirements at a cost that could fit within
the proposed budget. A structural design
for optimum material utilisation, low-cost
moulds, a fast process independent of labour
skill and capable of reproducing the parts
with the same quality was a must.
Carbon and glass fibre hybrid stiffeners were
designed and developed meeting all the before-mentioned requirements and produced
using the user-friendly and low-exotherm
resin solution developed by Huntsman
Advanced Materials.
The project also required the production
of slip-free, low-weight (<25kg), chemically- and mechanically-resistant GFRP
stairs that would not exceed a thickness
of 20cm. Composites produced by resin
transfer moulding (RTM) using a resin
from Huntsman Advanced Materials
were identified as providing the optimum
solution.

Adhesives played their part
In keeping with the design concept and
performance aims, adhesives were selected by Acciona to bond the lighthouse's
composite components together. Araldite®
adhesives were chosen in preference to
mechanical fastenings, which would detract from the look and add unnecessary
weight to the final structure.

Araldite® industrial adhesives have been
used extensively in the construction sector
for decades, primarily for applications
such as crack injection, bonding old
concrete to new, segment bonding and
concrete strengthening, where they are
specified for a combination of performance characteristics including high
mechanical strength, high chemical and
water resistance and their effectiveness
even in adverse weather conditions.
They are recognised for working across
a range of substrates with formulations
developed to cover the bonding of dissimilar materials such as metals from mild or
galvanised steel, to aluminium, brass and
ferrite, as well as most modern plastics,
ceramics, glass, rubber and wood.
Variations in formulations deliver a precise product profile matched to a specific
process, assembly or manufacturing need
with variables such as pot life, sag resistance, cure time, gap filling and shrinkage
taken into account.

achieved using innovative materials, form
factors and processing technologies. It
is also a great example of cross-industry
collaboration in action. It just goes to
show that when companies share research,
technologies and ideas, success in innovation is inevitable.

High-performance structural adhesives
also tend to be the complementary material
of choice for many structural composite
applications. When adhesive and composite
systems are used in combination, they deliver excellent mechanical performance capabilities to structures and save time, money
and process complexity. Adhesive bonding
enables the most efficient use of composites,
maximising their long-term potential while
optimising manufacturing methods with
easy handling and processing.

Opening new markets
and applications

Cost and production time savings
Combining a long pot life with fast curing,
and thixotropic properties that facilitated
easy application on the tower's vertical
surfaces, the Araldite® epoxy-based structural adhesive specified for this project
delivered significant cost and production
time savings. This adhesive also added to
the strength of the composite structure
and contributed to its lightweight and
aesthetic appeal.
The lighthouse project focuses on short
and efficient manufacturing cycle times
of CFRP and GFRP composites. This was

56 jec composites magazine / No106 July 2016

Fast and easy installation
Before the lighthouse was commissioned,
final tests had been conducted to ensure it
met load and wind requirements.
In comparison to concrete builds that
typically require 28 days to be fully cured
and an additional 21 days to install, the
all-composite lighthouse was fabricated
off-site while the site preparation was
taking place and was installed in less than
20 days.
Due to its advantageous size-to-weight
ratio - 20 metric tons for the 35m tower -
a lightweight crane installed the structure
in less than six hours.

With inherent properties such as low
weight, high strength-to-weight ratio, better
chemical resistance and low maintenance,
composites present versatile opportunities
in the construction and civil engineering
industries. In meeting strict architectural, strength and service life expectancy
requirements, this vertical tower structure
reflects how new markets are opening up in
rapidly growing countries and applications
with extreme environments.
The technologies developed and proven for
the lighthouse project are currently under
consideration in numerous other projects
including towers for wind energy, columns
for bridges and mobile antennas.
Other partners involved in this project
working with Acciona Infraestructuras
S.A. and Huntsman Advanced Materials
included Autoridad Portuaria de Valencia,
Siegrist & Moreno S.L, Aimplas, Dow,
Saertex and Owens Corning. n
More information:
www.huntsman.com

http://www.huntsman.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #106 - July 2016