Introduction to an Effective Concrete Setting Accelerator – Yara NitCal

Concrete and Calcium Nitrate
Introduction to an effective setting accelerator
Dr.-Ing. Wolfram Franke
Yara Industrial
Application Development
Yara Technology Center
Wolfram.Franke@yara.com
www.yara.com

4/09/2014 Page 2W.Franke
 General demand for non-
corrosive accelerator
– Setting Accelerators are required
to improve performance and
productivity
– Chloride-based accelerators
cause severe corrosion damage
 Yara* performs systematic
research on possible industrial
applications for calcium nitrate
– In 1992 Norsk Hydro approached
SINTEF, Trondheim/Norway, to
start in-depth research of
possible concreting applications
* formerly Norsk Hydro
Why Calcium Nitrate?

What brought the breakthrough ?
 A unique project involving CN was the construction of the “Troll” oil/gas
platform in the North Sea (construction 1991-1994)
 Slip formation led to the need for a plasticizer - Productivity went down:
– A non-corrosive accelerator was needed
Troll: the largest movable structure on Earth

 Calcium Nitrate (CN) as a molecule
– Setting: Calcium speeds up the early hydration stage
– Strength enhancement and Corrosion inhibition: Calcium reduces porosity
– Corrosion Inhibition: Nitrate oxidizes dissolved rebar iron and forms a
protective layer around rebar, comparable to the effect of Nitrite
 CN benefits over comparable alternatives
– CN does not corrode reinforcement, unlike Calcium Chloride
– CN does not provoke alkali aggregate reactions, unlike Sodium Nitrate or
Sodium Nitrite
– CN is environmental friendly, unlike Calcium Nitrite
What does Calcium Nitrate do ?

 CN is a setting accelerator
– Start of setting is shifted forward
in time
– The reactions intensity within
setting is not affected (no
hardening accelerator)
 Efficiency depends strongly on
type of cement
– CEM I 52.5, CEM II-V, CEM II-L
benefit over full temperature range
– CEM I 42.5 benefits on low
temperatures only
Calcium Nitrate as a setting accelerator
©H.Justnes
15
2 0
2 5
30
35
4 0
4 5
50
55
60
0 3 6 9 12 15 18 2 1 24
temperatureindegC
time of experiment in h
Temperature development
(cement paste, w/c= 0 .4 5, 2 0 deg C)
CEM II A-V 42.5 R
CEM II A-V 42.5 R
+ 1CN
CEM I 52.5 N
"white"
CEM I 52.5 N
"white" + 1CN

4/09/2014 Page 6W.Franke 4/09/2014 Page 6
HESQ: Product and Application
development for high quality concrete
production

 CN as water-free molecule is
difficult to obtain and handle
– Strong oxidizer with challenging
REACH classification
– Not available on the market
 CN needs are provided as
specialized products with improved
handling and storage properties
– Liquids:
• CN solutions with different
concentrations
– Solids:
• Calcium-Ammonium-Nitrate
(free flowing granule)
• Calcium-Potassium-Nitrate
(free flowing granule)
• CN tetra hydrate
(wet powder)
How to get Calcium Nitrate ?
0 % 20 % 4 0 % 60 % 8 0 % 10 0 %
CN 45% old
CN 45% new
CN 50 % old
CN 50 % new
NitCal
NitCal/K
CN Tetrahydrate
Composition of CN products
Ca(NO3)2 NH4NO3 or KNO3
Crystal Water Free Water
??
?

 Market support
 Coordination of external R&D
 Customer communication
 Workshops and technical meetings on NitCal
 Concept development
 Screening tests, pre-testing
 (ISO certified production)
 Certified testing
 Expertise
 Market Support
 Special projects on Lignosulphonate and NitCal
 Durability testing
 Corrosion Inhibition, Models, Simulation
Market Support, Research and Development to
ensure high quality concrete production
University of
California
UCLA

 The recommended CN dosages depend strongly on
– Cement type used, the “antifreeze” feature in particular demands prior testing
– Purpose of dosage
 CN dosages refer to CN active contents
– important when blends, hydrates and solutions are used!
Which dosages are recommended ?
0 1 2 3 4 5
Setting Accelerator
(reduce setting time up to 50%)
Counteraction of Plasticiser
(reduce setting time by 4h at +20°C)
Antifreeze
(reduce setting time by up to 3h at +5°C)
Strength enhancement
(additional 10% of compressive strength)
Corrosion Inhibitor
(increasing duration to corrosion start by 20%)
dosage as % of cement weightcharacteristic up to
(Given recommendations need to be proven in pre-tests with the local cement)

Thank you for your attention!
Yara Porsgrunn Plant

• Yara disclaims all responsibility and liability for any expenses, losses,
damages and costs incurred as a result of relying on or using the
information contained in this document. Yara reserves the right to adjust and
revise this document at any time.
• Any forward-looking statement made by Yara in this document is based only
on information currently available to Yara and speaks only as of the date on
which it is made. Yara undertakes no obligation to publicly update any
forward-looking statement.
• No rights, including, but not limited to, intellectual property rights, in respect
of this document are granted to any recipient unless specifically stated.
• ©Yara International ASA. All rights reserved.
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Introduction to an Effective Concrete Setting Accelerator – Yara NitCal

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Introduction to an Effective Concrete Setting Accelerator – Yara NitCal