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Trial and BASF Product Recognised in International Journal of Electrochemical Science

July 22, 2012

DUBAI, UAE, July 23, 2012 /PRNewswire/ –

– American University of Sharjah study rates BASF’s Rheocrete 222+ top steel corrosion
inhibitor

The American University of Sharjah (AUS), a nationally and internationally accredited
educational institution in the United Arab Emirates (UAE), has conducted a trial to test
the effectiveness of corrosion inhibitors used in steel-reinforced concrete in
construction. Rheocrete 222+, a combined waterproofer and organic corrosion inhibitor from
BASF Construction Chemicals, received top honours. The trial, after stringent review, has
been accepted for publication in the International Journal of Electrochemical Science. For
BASF, this is industry recognition at a high level for a product that has proven itself in
projects around the globe for over two decades.

See full trial, Reduction of Corrosion Process in Steel Bars Using Inhibitors

http://www.electrochemsci.org/papers/vol7/7076472.pdf

Says David Bowerman of BASF Construction Chemicals’ Admixture Systems Division: “This
trial by AUS puts the theory around corrosion inhibitors to the test and provides insight
into the performance of different formulae. The results speak for themselves with regard
to the capabilities of Rheocrete 222+, underlining the effectiveness of the product but
also highlighting the advantages of organic corrosion inhibitors over inorganic solutions
- which is particularly relevant to construction in the UAE region.

“Ground water and chlorides corrode the steel in reinforced concrete, weakening
structures. Unless precautions are taken at design stage, structures are likely to require
extensive repair to keep them in service. In the Middle East, concrete frequently fails to
meet its design life in the hot, humid, salt laden atmosphere. Corrosion inhibitors can
reduce the lifecycle costs of structures in aggressive environments and enhance their
design life. However, the effectiveness of corrosion inhibitors can vary, so selecting the
right product is vital.”

The AUS trial: Reduction of Corrosion Process in Steel Bars Using Inhibitors

Corrosion inhibitors act in a number of ways to retard or delay the corrosion
mechanism: in simple terms, they form a chemical inhibition film on the steel
reinforcement at either the anode or cathode, or both. Three commercial inhibitors were
used in the AUS study: a Calcium Nitrate Inhibitor (CNI), an anodic corrosion inhibitor
(ACI), and the RHEOCRETE 222+ corrosion inhibitor, which is a dual formulation.

A corrosion cell comprising four concrete beams was constructed. Three beams made use
of different corrosion inhibitor admixtures and the forth was a control beam with no
addition of admixture. Super plasticizer was added to maintain approximate 100mm slump for
the four mixes.

The performance of admixtures against corrosion was highest for RHEOCRETE 222+ than
others. The same findings were achieved from the corrosion mass loss which was calculated
theoretically using Faraday law. Visual observation of the broken samples also confirmed
these findings.

These results can be further tested using Life 365 (http://www.life-365.org), a
free and independent computerised corrosion modelling program that shows the effectiveness
of Rheocrete 222+ and demonstrates the reduction in life-cycle costs resulting from its
use.

Organic corrosion inhibitors win hands down

Ideally, in construction, contractors want a corrosion inhibitor that is
environmentally friendly, is capable of slowing down chloride penetration through the
capillary pores of the concrete, will reduce permeability of concrete, and will form a
protective corrosion resistant film around the steel reinforcement. Also, since dosing
admixtures like these into a concrete mix can adversely affect workability, initial slump
and setting time — and mitigating these effects can additionally affect strength
development and concrete-steel bond strength — a product that does not produce these
effects is highly desirable.

There are two key types of corrosion inhibitor to choose from: organic and inorganic.
Inorganic corrosion inhibitors (typically nitrate based) act as a passivator,
counteracting the damaging action of chloride ions on steel through the presence of
nitrate ions. However, they also act as an accelerator when dosed into fresh concrete,
increasing slump loss and reducing setting time. A big disadvantage is that, if
underdosed, inorganic corrosion inhibitors can accelerate localised corrosion. Unlike
organic inhibitors, which have a fixed dosage, to work efficiently calcium nitrate based
admixtures require knowledge of the likely chloride content of the concrete throughout the
lifespan of the structure. This is almost impossible to determine.

The advantage of dual action organic corrosion inhibitors is that they can diffuse
through the concrete and form a corrosion inhibiting layer on the metal surface. They also
reduce the porosity and permeability of the concrete to water and chlorides.

Rheocrete 222+ is the only product in the AUS test that combines two forms of
protection: a hydrophobic pore-blocking waterproofer and an organic inhibitor which forms
a corrosion-resistant protective film on the reinforcing steel. The inhibiting action is
anodic, reducing the dissolution of iron, and cathodic, acting as a barrier to oxygen and
moisture.

Optimising the benefits of Rheocrete 222+

Says Bowerman: “It’s the unique formula of the Rheocrete 222+ that makes it so
effective. The findings of the AUS trial describe its action concisely: ‘The Rheocrete
222+ admixture is a combination of amines and esters in a water medium. The ester
component acts by lining the pores of the cement matrix, slowing the rate at which
chlorides and moisture enter the concrete. The amines adsorb onto the reinforcing steel to
provide an additional barrier to corrosion by forming a protective film. This film slows
the corrosion process once it begins by preventing chlorides from reacting with the
reinforcing steel, and by depriving the corrosion process of moisture’. Dual-action
inhibitors also reduce deterioration caused by ingress of sulfates as a consequence of the
concrete’s reduced permeability.”

Rheocrete 222+ has a 20-year international track record – it was first widely used in
the USA but is now also available in the Middle East for over 10 years. The product is
also sold in Asia/Pacific and Europe. It’s been used in a number of high profile
construction projects, including construction at the Khalifa Port and Industrial Zone;
construction and repair of bridges, culverts and roads in Oman; at Jebel Ali Power Station
K; Halul Port and Doha West Sewage Treatment projects in Qatar; the Emirates Twin Towers;
and more.

But best practice goes hand in hand with quality outcomes. Notes Bowerman: “The use of
fully-compacted, properly cured concrete will ensure maximum durability of concrete –
putting a high-quality admixture into low-quality concrete will not get you the results
you need. BASF has a full range of systems and solutions to meet specific needs.

“In addition to Rheocrete 222+ we recommend assessment of BASF’s Smart Dynamic
Concrete technology which uses the RheoMATRIX viscosity-modifying admixture along with a
superplasticiser from our Glenium range (formulated from polycarboxylic ether polymers
produced in-house by BASF) which will assist you to achieve the specifications required
for your application. Curing compounds from our Masterkure range will furthermore ensure
full hydration of the concrete and minimise the risk of cracking.”

Concludes Bowerman: “When it comes to corrosion, prevention is better than cure. While
corrosion inhibition solutions may initially cost more, the value in terms of greater
durability, lower lifecycle costs and extended design life, more than make up for it.”

About BASF

BASF is the world’s leading chemical company: The Chemical Company. Its portfolio
ranges from chemicals, plastics, performance products and crop protection products to oil
and gas. We combine economic success, social responsibility and environmental protection.
Through science and innovation we enable our customers in almost all industries to meet
the current and future needs of society. Our products and system solutions contribute to
conserving resources, ensuring healthy food and nutrition and helping to improve the
quality of life. We have summed up this contribution in our corporate purpose: We create
chemistry for a sustainable future. BASF posted sales of about EUR73.5 billion in 2011 and
had more than 111,000 employees as of the end of the year. BASF shares are traded on the
stock exchanges in Frankfurt (BAS), London (BFA) and Zurich (AN). Further information on
BASF is available on the Internet at http://www.basf.com.

About BASF Construction Chemicals

BASF’s Construction Chemicals division is the leading supplier of chemical systems and
formulations for the construction industry. Continuous innovation and tailor-made
solutions ensure its customers are more successful. Its product portfolio comprises
admixture systems, cement additives, solutions for underground construction, repair
systems and performance grouts, expansion control systems, waterproofing solutions and
sealants, flooring systems, tile fixing systems, wall systems and solutions for wood
protection. The division operates production sites and sales centers in more than 60
countries and achieved sales of about EUR2.2 billion with approximately 7,000 employees in
2011.

        Karen Gallacher-Smythe
        Phone: +971-50-459-4713
        karen.gallacher@basf.com
        BASF FZE
        PO Box 61309, Jubail, Dubai
        United Arab Emirates

SOURCE BASF FZE


Source: PR Newswire