News Latter VOL_4.indd - SECAR®, solutions for refractories

No.4 | October 2012
Regional Workshop on Improving Castable
Refractories held in Visakhapatnam
Kerneos India and the Indian Ceramic Society-Vizag
chapter jointly organized a first of its kind workshop in
Visakhapatnam for the benefit of small and medium scale
refractory industries in South India on 9th August 2012.
The workshop was inaugurated by Mr. Y.S.S. Rao, former
CMD of Visakhapatnam Steel and ex MD of JSW Steel.
Delivering the inaugural address, Mr. Rao stated that
calcium aluminate cements play a very vital role in
manufacturing high quality refractory castables which
are used in various process industries like steel, cement,
glass, foundries etc. He further added that the growth of
refractory industry was linked to the growth of iron and
steel sector. Mr. Rao envisaged continuous growth in the
steel industry and in turn, growth for refractory industry
as well.
Mr. P. B. V. Krishna Rao, Vice Chairman of ICS Vizag
chapter welcomed the gathering comprising 143
delegates from 43 companies. Mr. Segi P Idicula-MD of
Kerneos India delivered the key note address. Mr. Chris
Parr-Executive Vice President of Kerneos SA, Mr. Benoit
Valdelievre-Sr. Technical Director of Kerneos SA and Dr.
Goutam Bhattacharya-Technical Developer of Kerneos
India presented papers on technology, quality and
application. The concluding session was live and vibrant
with numerous queries and interactions from participants.
Dear Friends,
Our emphasis at Kerneos is
not only to keep innovating
but also to update
our customers on the
technological innovations
in Calcium Aluminate
binders. These evolutions
and resulting value added
formulations positively impact the refractory castable
performance. In the last issue of Secar Gazette,
I had communicated to you about the Regional
Workshop we were organizing on 9th August 2012
in association with the Vizag Chapter of the Indian
Ceramic Society on “Improving Castable Refractories
with Calcium Aluminate Cements”. The event in
Vizag was attended by almost 150 participants
from refractory, steel and other industries as well
as research institutes. The quality of deliberations
and the hunger of the participants to learn more
gave us the impression that the refractory industry
is definitely poised for a makeover in their product
offerings.
Motivated by the grand success of our Vizag
event, we have now planned another Regional
Workshop in Ahmedabad on 21st February 2013
to benefit customers in the Western, Northern and
Central India. I encourage early confirmation from
participants to avoid last minute disappointment
since we have limited the audience to 150 numbers.
The world is reeling under a contracted economy
and India is no exception. While the Government
of India as well as the RBI has been working on
recovery measures, industries have turned to cost
optimization to address the shrinking margins.
Calcium Aluminate Binders from Kerneos play a
highly significant role in optimizing cost of refractory
castables and at the same time contributing to the
top end quality and performance. Please feel free to
contact us for any technical support that you may
need in this connection.
This issue of Secar Gazette covers our last Vizag
Workshop, an interesting article on “Testing
calcium aluminate cement” besides “Market Pulse”,
Technical Tips and Kerneos Corner.
Festival season is round the corner and let me
take this opportunity to Wish You and Your Family
Season’s Greetings!
Segi P. Idicula, Managing Director
Kerneos India & Middle East Operations

Market Pulse
Infrastructure Projects in India delayed
India’s infrastructure sector has been in
the doldrums for quite some time now
because of huge delays in infrastructure
projects. The finance ministry estimates
that infrastructure projects worth Rs.1.46
lakh crore have been delayed.
• In the road sector, projects have
been delayed because of land acquisition
and environmental issues. Sixteen major
highway projects worth Rs.15,000 crore
in four states have been stalled, awaiting
environmental clearances from the Ministry
of Environment and Forests (MoEF). Delays
in obtaining environmental clearance
have stalled many crucial coal production
projects.
• Delay in capacity expansion at various
ports is taking a toll on exporters and
importers. The fourth container terminal at
Jawaharlal Nehru Port Trust is delayed and
facing obstructions. The Rs.6,700 crore
project is said to have a capacity of 4.8
million containers a year.
• The South Korean steel giant Posco is
facing major roadblocks in completion of
its 12-million tonne mega steel project in
Odisha.
Government of India has planned to take
measures to boost infrastructure growth
after the record low GDP growth of 5.3%
witnessed in the January-March quarter
of 2012. Prime Minister announced the
setting up of an investment-tracking system
which will review projects periodically to
ensure that issues are quickly identified
and resolved.
The Prime Minister said, “The government
alone cannot invest this amount. Therefore,
importance is being given to public-private
partnership.
New National Steel Policy
In view of changed economic environment,
both globally as well as domestically,
Ministry of Steel has initiated the process
of drafting the New National Steel Policy
in place of existing National Steel Policy
2005. An Apex Committee, headed
by Secretary, Ministry of Steel and
consisting of representatives of Planning
Commission, Ministries/ Departments of
Central Government and concerned State
Governments has been constituted for
monitoring the process of formulation
of the New National Steel Policy. Four
Task Forces have been constituted under
the Chairmanship of eminent experts to
study, analyze, consult and formulate
draft policy documents in different aspects
of the subject. These task forces are
currently in various stages of discussion
and consultation with the stakeholders
and experts in the industry to identify all
the relevant issues and come up with the
policy prescriptions. A final view on the
New National Steel Policy will be taken on
receipt of reports.
The new steel policy will be put in place
in six months to facilitate rapid growth of
the domestic steel sector by ensuring faster
capacity addition. “A Steel Ministry panel,
constituted to frame the new Steel Policy
will finalise the draft in two months,”as
informed by Joint Secretary Steel during
Steel Summit held at New Delhi in
March’12.
Tech Edge
The shelf life guarantees for
Secar ® 68V and Secar ® 70V
were established at 6 months
based on initial testing of
laboratory, pilot scale and
full production batches.
Further to more extensive
testing conducted over
extended time periods and
coupled with improvements
to the packaging used, the
shelf life for Secar ® 68V and
Secar ® 70V is extended to
9 months. However, the
storage condition should be
appropriate, as explained in
the product data sheet - in
common with all hydraulic
binders, SECAR ® 68V and
Secar ® 70V must be stored
in shrink wrapped condition
on pallet, as supplied, in dry
conditions under a covered
storage area.
During the test program,
the products were packed
in standard bags and on a
shrink wrapped pallet with 5
layers. Samples were stored
in a warehouse in Singapore
(high ambient temperature
and humidity) and sacks
returned to KDCC (Kerneos
Development Centre,
China) each month for
testing. The products were
well packed and stocked
according to best practice
(on pallet, off the ground,
with shrink wrapped film in
a ‘dry’ warehouse). After a
bag was removed the plastic
film of the pellet was closed
to avoid exposure of bags to
the air.
The mortar and application
test of flow, setting and
strength (6h and 24h)
showed that there was
less than 5% change in
properties from time zero to
9 to 12 month storage. This
variation is almost within
the normal variation of the
test method.
Kerneos Corner
Environmental Clearance for
Kerneos India Project
Following the acquisition of a
piece of land of 8.3 hectares in
February 2012, Kerneos was
granted in August 2012 the
Environmental Clearance for the
project by the state environment
authorities. This is a key milestone
in the construction of the new
Kerneos plant in India, scheduled
to start operation by the end of
2014.
This green field sintering unit of
30,000 tons per year capacity
dedicated to the manufacture
of calcium aluminate cements
for refractory applications will
be established in the area of
Visakhapatnam city in Andhra
Pradesh and will produce a
range of high quality products
specifically designed for the
Indian market needs.
Regional Workshop in
Ahmedabad in February, 2013
Kerneos is organizing a regional
workshop on Calcium Aluminate
Cement based Castable Technology
and its Application in Ahmedabad,
Gujarat on Thursday, 21st February,
2013 in association with the Indian
Ceramic Society Gujarat Chapter.
Prime objective is to share information
on the latest castable technology
and main focus will be the Refractory
manufacturing industries in Western,
Northern and Central India.

TESTING CALCIUM ALUMINATE CEMENT
G. Bhattacharya*, B. Valdelièvre* and C. Parr.
*Kerneos, Kolkata, India
INTRODUCTION
Cement tests, if required, need to be done carefully
to ensure accuracy of the results. Often neat
cements are used for testing without a suitable
temperature control. Neat cement tests generally
give higher variability than standard sand mortar
tests. This is because of the difficulty of nucleation
of calcium aluminate hydrates in absence of
nucleating surfaces for the neat cement paste.
Also, cement hydration is temperature dependent
and the setting shows anomalous nature between
~24°-28°C, making temperature control essential
for cement testing. Besides, appropriate choice of
ambient temperature (20°C) is essential to ensure
that the test does not bring additional variability.
Moreover, there is no direct correlation between
cement and castable setting, particularly for
deflocculated castables, which are influenced by
additives and other bond phase materials.
Last year during a technical meeting, a customer
told us that when he tested a calcium aluminate
cement, he found its results were completely
unsatisfactory and they were almost deciding not
to use the cement. However, when they tested the
cement in one of their products, it gave excellent
results and the tests on bulk production lots were
equally good. Often the answer lies in testing
calcium aluminate cement appropriately.
Despite these major issues on testing cements
properly, there is almost a consensus among
castable manufacturers of India that cement needs
to be tested regularly. Cement is considered too
important a raw material to be left completely
untested. The key objective is of course to monitor
quality of the cement lot. Some even think that
they should be able to correlate cement properties
with those of castables. For cements there is no
universally accepted test method. In this article, a
few key factors of cement tests, which influence
the results, will be discussed.
SET TIME TEST - NEAT PASTE VS. MORTAR
Neat paste test has been popular in India for long,
which was followed in many parts of the world
earlier. However, this test was updated to mortar
test. Set time and exo peak time variations of
Secar 71, a 70% alumina cement are compared
by mortar (Figure 1a and b) and neat paste tests
(Figure 1c and d) at 20°C using seven random
samples. The set time tests were conducted using
an automatic Vicat needle, which is programmed
to fall at specified intervals, ensuring high accuracy
of the results. AFNOR (EN 14647) sand was used to
make the mortar and ratio of sand: cement: water
was 6:2:1. Neat cement test results with both Vicat
and exo peak showed higher variation than those
with the mortar, indicating high inherent variability
of the neat cement test, which can be explained
Setting (mins)
Setting (mins)
250
200
150
100
50
0
400
350
300
250
200
150
100
50
0
210
198
190
Initial set
195
200
190
200
1 2 3 4 5 6 7
250
190
278
Time (hrs)
4.57
4.88
4.45 4.5 4.5
a) b)
Initial set
200
310
375
200
1 2 3 4 5 6 7
Time (hrs)
c) d)
6
5
4
3
2
1
0
20
18
16
14
12
10
8
6
4
2
0
Exo max
4.21
5.05
1 2 3 4 5 6 7
9.85
11.5
Exo max
10.8
6.6
8.7
18.8
1 2 3 4 5 6 7
Figure 1: Variation of a) initial set time and b) exo peak time in a set of random Secar 71
samples using AFNOR mortar test and those (c and d respectively) with neat paste test
by the mechanism of cement hydration reaction
(Figure 2).
hydrates
ionic concentration
1 2 3
time
exotherme
Figure 2: Mechanism of cement hydration
reaction
The first step includes dissolution of cement
particles in water leading to rapid increase of
ionic concentration, little hydrate formation and
no temperature increase. The second step is
nucleation, when ionic concentration starts to
decrease slowly, hydrates start to appear and again
no temperature increase is observed. The final
stage is massive precipitation of hydrates which
shows rapid drop in ionic concentration, increase
in hydrates and exothermic peak.
Nucleation of cements with large amount of
Figure 3: Presence of nodules in Secar 71
neat paste sample (w/c=0.27) after washing
between initial and final setting (from
Lafarge laboratories in 1960s)
calcium aluminate (CA) phase (such as Secar 71)
is difficult as it takes place homogeneously from
solution and presence of nucleation sites help
reducing nucleation time. Pure CA nucleation
takes 13-20h. Difficult nucleation of Secar 71 leads
to nodules which are often visible (Figure 3). C 12
A 7
,
fine fillers such as sand and lithium ions generate
nucleation sites decreasing set time. The cements
with more C 12
A 7
are found to be more regular in
neat cement test than those with less C 12
A 7
, as
shown in the conductivity plots of several samples
7.5

mS/cm
Time minutes
350
300
250
200
150
100
50
AFNOR MORTAR
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
Temperature°C
Figure 5: Initial set time of a 70% alumina
cement as a function of ambient temperature
Temperature°C
2,8
2,6
2,4
2,2
2
1,8
1,8
A
10 min
120 min
1,4
0 60 120 180 240 300 360 420 480 540 600 660
Time (min)
Figure 4: Variation of conductivity of
two calcium aluminate cements (random
samples) – A & B as a function of time; A
has more C 12
A 7
than B.
of two cements – A with more C 12
A 7
than B
(Figure 4).
VARIATION OF SET TIME AS A FUNCTION OF
TEMPERATURE – ANOMALOUS SETTING
Cement hydration reaction is temperature
dependent. It is generally expected that with
T°C
50
45
40
35
30
25
20
15
10
5
0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5
Time hours
42°C
35°C
32°C
28°C
25°C
20°C
12°C
8°C
Figure 6: Variation of exo peak temperature
a 70% alumina cement as a function of
ambient test temperature
increase in ambient temperature the reaction
will be rapid and set time will decrease. Calcium
aluminate setting as a function of time is not
very simple. Figure 5 shows that setting time of
a 70% alumina cement decreases from 5°C to
20°C, remains almost stable up to ~24°C and then
increases till 30°C, which is followed by a rapid
B
Increase of solubility
decrease of supersaturation
28°C
Acceleration of
nucleation by temperature
°
Figure 7: Evolution of nucleation time of
CAH 10
and AH 3
with temperature
drop above this temperature. The exo profiles
and the peak temperatures times also reveal the
similar behavior of the calcium aluminate cement
(Figure 6). This unexpected increase of set time
or anomalous setting from ~24°C to 28-30°C is
common in pure calcium aluminate cements and
is absent or less prominent with 80% aluminacontaining
cements which may contain additives
and alumina. The anomalous setting may be
explained by an increase in solubility of CAH 10
,
which forms predominantly below 28°C. Increased
solubility leads to a decrease in supersaturation
and therefore, difficulty in nucleation. Above 28°C,
(C 2
AH 8
+AH 3
) form preferentially, as the nucleation
of AH 3
becomes quicker due to thermal activation
and the solubility of AH 3
does not change with
increase in temperature (Figure 7).
CORRELATION BETWEEN CEMENT AND CASTABLE
SET TIME AT DIFFERENT TEMPERATURE
PTT (min)
3500
3000
2500
2000
1500
1000
500
0
PTT (min) Cement (AFNOR)
PTT (min) low cement castable
20 23 25 28 30 32 35 38 42 45
Ambient temperature (°C)
Figure 8: Variation of PTT (min) of cement
and a low cement castable with this cement
as a function of ambient temperature
The cement set time may not be easily correlated
with those of castables made from this cement. For
conventional castables this relation may be relatively
simple, although the nature of aggregates may
bring some difference or variability, particularly for
those aggregates which bring soluble ions such
as alkalis. The AFNOR sand is non reactive. The
workability and setting reactions of deflocculated
castables are influenced by fine fillers and additives
and they behave quite differently from the
cements, as a function of ambient temperature
(Figure 8). Deflocculated castables do not show
anomalous setting and their set times decrease
steadily with increase in ambient temperature.
CONCLUSION
Cement setting test, although quite popular
among the users, does not bring a major
value due to major flaws in the test commonly
practiced using neat cement without appropriate
temperature control. Neat cement test often gives
wide variability, particularly for CA-rich cements
due to the difficulty to nucleate, which is an
essential step just before precipitation of calcium
aluminate hydrates. Nucleating surface generators
help. Standard sand is often used for this purpose
to make a mortar, which gives regularity in setting
and is used widely all over the world. Also, it is
important to choose the appropriate temperature
of testing the setting of cement, as cement shows
anomalous setting from ~24°C to ~28°C. 20°C
may be considered as an appropriate temperature
and is often used for testing calcium aluminate
cement in most parts of the world and mentioned
in major international standards (e.g. EN 14647). It
is also essential to note that there is no simple 1:1
correlation between cement and castable setting,
particularly for deflocculated castables which are
influenced by additives and other bond phase
components. Considering all these aspects of
cement tests, as all modern castable manufacturers
in the world have adopted, it may be better for local
manufacturers to stop testing cement and rely on
the advance process and quality control systems of
Secar products, which may be demonstrated with
quality data. It may be easier and more effective
for castable manufacturers to perform application
tests of calcium aluminate cement in standard
castable composition.
Kerneos India Business section is
now available on our website. Please
visit www.secar.net for access to
technical papers, brochures, product
data sheets of Indian as well as
international products, all editions
of Secar Gazette, FAQ etc.
For more details mail : goutam.bhattacharya@kerneos.com
Kolkata Office : KERNEOS INDIA
3B – Shristi Bldg / 3rd Floor, 12, Ho Chi Minh Sarani, Kolkata 700 071, Tel: +91 33 3052 2315/16 Fax: +91 33 3052 2681
Head Office : KERNEOS S.A
8 Rue Des Graviers, 92521 Neuilly Sur Seine Cedex, France, Tel: +33 1 46 37 90 00 Fax: +33 1 46 37 92 00