fast setting GGBS binder - with practically no carbon footprint - presented at IBAUSIL Weimar Germany 2023

1. Quaternary Cement
low carbon rapid set GGBS cement binder

2. European Commission aims to make
the EU climate neutral by 2050
By 2030 - CO2 emissions should be reduced by at least 55 %
compared to 1990 !

7. China is estimated to produce 50 percent of world’s production, being world’s
biggest cement producer.
not all of it is consumed in China, but an increasing amount is exported
world wide

8. mandatory reduction of

9. silica and limestone are mixed and sintered together in a
kiln at 1400–1500 degrees Celsius , about 2,500 degrees
Fahrenheit.
Limestone at this temperature transforms to quick lime or
calcium oxyde reacting with silica to form tricalcium silicate
so called cement clinker.
Most of the carbon dioxide is emitted ;
After cooling this clinker is ground to a fine powder.
Gypsum is added to slow down the reaction speed.
When water is added it hardens to a rock-like material
binding fillers to make mortar or concrete
Cement production

10. Cement clinker
• cement production contributes
7% of world wide CO2 emission
mainly through decarbonation of
limestone
• 1 ton of cement clinker emits
~ 800 kg of CO2
• carbon dioxide emission tax
expected to double within next
decade
• currently ~ € 90,= per ton
• carbon dioxide emissions tripled in
last three decades to
3 billion tons /y.
• cement production consumes most
of natural resources

11. Actions
• replacing clinker amount by SCM’s – fillers
• using alternative binders like CSA cement or
geopolymers
• lowering cement amount by volume
concrete, mortar
• reduction concrete volume (3D-printing,GRC)
• improving efficiency of binder system

12. Reducing clinker content
1. Pozzolans
natural/waste materials rich in silica reactive in the presence of
lime
When water is added it reacts like cement with following
characteristics;
• slow set
• long time to build up strength
• improved flexural strength
• low ultimate compressive strength
• more durable in time
Today more pozzolan materials are derivate from industrial
waste like fly ash making it more sustainable construction
material
To provide sufficient strength they are often mixed with
Portlandcement

13. Reducing clinker content
2. GGBS Ground Granulated Blast-furnace Slag)
an aluminosilicate / cementitious material a by product from iron
making.
When water is added it reacts like cement with following
characteristics;
• slow set (needs alkali activator Portladcement ,sodium
hydroxide(NaOH)sodium silicate(Na2SiO3)
• low initial strength
• low temperature on hydration
• low alkali (reduced risk on ASR Alkali Aggregate Reaction)
• improved dense matrix (better water impermeability)
• better corrosion and sulphate resistant
• more durable in time

14. Reducing clinker content
3. Limestone
fine ground calcium carbonate an inert filler with a high surface
area to even fine particle distribution to improve compacting
4. Chemicals
Superplasticizers (SPs), also known as high range water reducers, are
additives used for making high-strength concrete or to place self-
compacting concrete
polymer dispersions, latexes and redispersible powders
In this case strength is improved in low clinker content cementitious binders
by reducing the water to cement ratio – and/or adding organic compounds to
the matrix

15. So if we can produce cement with the least materials through mixing some of the
supplementary materials—as I said, fly ash or slag with the cement—during
production, that's another way to produce cement that has the least of the effective
material that results in the larger emissions of CO₂. Canada has lots of work in this,
and they produce what we call slag cement, and there are other countries as well. But
that was since early 2000; they produced cement that has a considerable percentage
of it as slag, and it works well for different construction purposes. So, these are the two
basic ways for reducing the CO₂ emissions in cement.
That's a good question. The two key trade-
offs for the construction industry are: how
fast the cement hardens and how strong it
becomes.
SGGBS
(Special Ground Granulated Blast-furnace
Slag)
GGBS is a vitrified substance which is a
byproduct of iron production in a blast
furnace. It consists primarily of oxides
of calcium, silicon, aluminium and
magnesium.

16. Clinker production
cement in making concrete world wide most abundant
building material
• quarring, transport
• grinding, preparation
of raw materials
• cooling, grinding, mixing

17. Source:McKinsey Laying the foundation for zero-carbon cement

18. Alternatives
AACM
Alkali Activated Cementitious Materials cements
hydrating through a chemical reaction between a
crystalline aluminosilicate; fly ash , GGBS (precursor)
and an alkaline or caustic solution sodium-,
potassium hydroxides or sodium silicate(activator)
Ternary Cement
blend of limestone filler GGBS and Portlandcement
clinker
LC3 Cement
blend of limestone filler, calcined clay
and ground Portlandcement clinker
Quaternary Cement
Portland cement blended with minimal three other
materials f.i. ground limestone, GGBS, fly ash, silica fume,
calcined clay, metakaolin, gypsum, calcium aluminate etc.

19. cement standard
call for 2 day strength

20. hybride cements
• nowadays developed hybride cements reduce
carbon footprint by replacing the content of ground cement clinker
by often less reactive materials SCM’s, like ground steel slag ,
limestone , calcined clays etc.
• this has however a big impact on setting times and / or early
strength development of the binder.
• In practice the binder content is kept at the same volume
• modification is needed to guarantee a stable binder to overcome
slow hydration and loss of early strength

21. GGBS
Ground
Granulated
Blast-furnace
Slag

22. Ground Granulated Blast-furnace Slag
iron
steel
making
decomposition
limestone
cooling
grinding

23. different production

24. Carbon emissions ;
• from the manufacturing
of 1 ton of cement cement ~800 kg.
• from the manufacturing
of 1 ton GGBS is ~35kg.
slow hydration
low heat release on hydration
not favorable to use in precast factories
or winter concreting

25. PORTLAND SLAG CEMENT
CEM II / B-S EN 197-1:2011
CEM II/B-S 32,5 N
CEM II/B-S
42,5 N
CEM II/B-S
52,5 N
compressive
strength
Mpa Mpa Mpa
2 days - ≥ 10,0 ≥ 20,0
7 days > 16,0
28 days ≥ 32,5 ≥ 42,5 ≥ 52,5

26. Low Carbon cement
Portland cement blended with two other materials f.i. ground limestone, GGBS, fly ash, silica
fume, calcined clay, metakaolin etc.
Ternary cement
Quaternary Cement
Portland cement blended with minimal three other materials f.i. ground limestone, GGBS,
fly ash, silica fume, calcined clay, metakaolin, gypsum, calcium aluminate etc.
generally these binders are latent hydraulic and generate a lower initial strength
modified to garantee a stable binder overcome slow hydration and loss of early strength

27. testing cement free binder
tested were two different types of GGBS
with addition of calcium sulfate

28. Table 1. Data for regular GGBS-RG used in this study.
Table 1. Data for regular GGBS-RG used in this study.
Table 1. Data for regular GGBS-RG used in this study.
Chemical Compound
SiO2 35,40%
Al2O3 11,20%
Fe2O3 0,70%
Na2O 0,50%
CaO 42,50%
MgO 8,10%
TiO2 0,50%
SO 10,00%
Physical Characteristics
D50 11 μm
Blaine 4500 gr/cm2
Density 2,865 g/cm3
GGBS-RG

29. Table 2. Data for GGBS-XF used in this study.
Chemical Compound
SiO2 1,92%
Al2O3 24,21%
Fe2O3 0,72%
Na2O 0,06%
CaO 45,46%
MgO 5,69%
TiO2 0,50%
SO 1,92%
CaF2 4,57%
Physical Characteristics
D50 9,6 μm
Blaine 6500 cm/gr
Density 2,965 g/cm3
GGBS-XF

30. Table 2. Data for GGBS-XF used in this study.
Chemical Compound
SiO2 1,92%
Al2O3 24,21%
Fe2O3 0,72%
Na2O 0,06%
CaO 45,46%
MgO 5,69%
TiO2 0,50%
SO 1,92%
CaF2 4,57%
Physical Characteristics
D50 9,6 μm
Blaine 6500 cm/gr
Density 2,965 g/cm3
GGBS-XF

31. Table 2. Data for GGBS-XF used in this study.
Chemical Compound
SiO2 1,92%
Al2O3 24,21%
Fe2O3 0,72%
Na2O 0,06%
CaO 45,46%
MgO 5,69%
TiO2 0,50%
SO 1,92%
CaF2 4,57%
Physical Characteristics
D50 9,6 μm
Blaine 6500 cm/gr
Density 2,965 g/cm3
GGBS-XF

32. Anhydrous Calcium Sulfate
Chemical Compound
SiO2 0,20%
Al2O3 0,15%
Fe2O3 0,10%
K2O 0,01%
Ca(OH)2 0,90%
MgO 0,10%
TiO2 0,50%
CaSO4 96,80%
CaF2 1,74%
Physical Characteristics
D50
10 μm
Blaine 6750 cm/gr
Density 2,965 g/cm3

33. XRD analysis
XRD analysis show both types of GGBS are mainly crystalline.
GGBS XF showed a content around double amount of Al2O3
and significant lower amount of SiO2
CaO content is slightly higher.
Markable ; contains calcium fluoride

34. Experimental
all compositions tested included both types of GGBS.
To facilitate the usage 1% of citric acid as set retarder was added
extreme fineness leads to a significant increase of water demand
for this reason 0,45% by weight of a super plasticizing agent is
used
Testing various different ratio of these three constituents
following formulation was chosen to be tested further.

35. Set min initial final Temp C. Time
GGBS-RG 440 gr >1440 x x x
water 176 ml after 2 days no strength was noticed
GGBS-XF 440 gr 03:30 04:30 30,7 06:40 min
water 176 ml
GGBS-RG 220 gr 10:00 21:00 45 01:53:10 H
GGBS-XF 220 gr
water 176 ml
Initial Experiment

36. Strength Testing
Strength testing was done at 24 hours, 2 and 7 days on
40x40x160mm prims confectioned in compliance with EN 196-1
Methods of testing cement — Part 1: Determination of strength.
Mentioned formulation was mixed with 1350 gr.
CEN Standard sand EN-196-1 Normsand mixed according standard

37. GGBS-RG 140 gr
GGBS-XF 200 gr
Anhydrite 100 gr
Normsand 1350 gr
water 180 ml
Mortar test
Note: a higher water/cement ratio was used.

38. 24 hours 2 days 7 days
Flex Comp Flex Comp Flex Comp
MPa 3.44 16,2 2,34 32,08 5,91 40,92
Mortar test results

39. Shrinkage / Expansion
In order to measure the shrinkage or expansion of the mixtures as
mentioned were placed into 40x40x160mm prisms according to
EN196-1.
prisms were connected to a micrometer, which digitally measured the
linear length change every hour, and followed for 7 days and after.
results up to 7 days show a relative small reduction of volume.

40. precipitation of ettringite
contributes in improving early strength and
accelerates drying and setting times

41. AFt (ettringite)
3CaO . Al2O3 . 2CaSO4 . 32H2O
AFm (mono sulfo aluminate)
3CaO . Al2O3 . CaSO4 . 12H2O 4CaO . Al2O3 . 19H2O
This formation improves the early strength and accelerates drying of the
binder.
As this chemical reaction takes place expansion occurs compensating
drying shrinkage.
Solutions in the presence of lime, alumina, calcium
sulfate complex hydrates are formed ;
precipitation of ettringite

42. Crystaline
C12A7
Amorphous Calcium Aluminate Cement
one of the best precursors in forming
AFt and AFm phase
(3 x more reactive calcium aluminate)
on hydration of main phase C12A7 (Mayenite)
Alumina ions are released quickly
reacting instantly with available sulphate

43. Amorphous Calcium Aluminate Cement
one of the best precursors in forming AFt and AFm phase – 3 x more
reactive calcium aluminate
hydration of main phase C12A7 (Mayenite) reacts
quickly with available sulphate to form
ettringite and mono calcium aluminate;
• account for high initial strength
• high density
• positive expansion, compensation of shrinkage
• bound excess water accelerate drying

44. Crystaline C11A7 · CaF2
C11A7 · CaF2 compound is isostructural with C12A7
forming a complete solid solution
Tests are ongoing to investigate the effect of combing amorphous
calcium aluminate and crystaline GGBS-XF and calcium sulfate
Results are to be published at a later stage
Amorphous Calcium Aluminate C12A7

45. FINDINGS
• regular GGBS marked RG showed no initial reactivity on its own,
and clearly needs some form of activation.
• results found in this empirical study show that regarding strength
development the fine ground special form of GGBS marked XF
achieved a relative high flexural and compressive strength.
• blending the two types lead to more than satisfying results
• addition of sulphate helps in a improving the early strength
development
• formation of ettringite crystals lead to a minimal expansion i.e.
reduction of shrinkage.
• small retardation in set times was noticed.

46. • XRD analysis of fine GGBS-XF showed presence of calcium
fluoride it is expected this contributed to activating the regular
slag used.
• C11A7.C phase is expected to have the most impact on hydration
performance of type XF.
• grinding this type to a finer particle size further boosted the
reactivity.
• it did increase the water consumption!
• pore structure and pore size were only marginally effected, and
strength development was satisfactory.

47. CONCLUSION
In conclusion, data shows that the optimum blends are the GGBS RG and XF
types combined with anhydrous sulfate.
GGBS can be activated by Type XF. Depending on the requirements the
addition can be varied and depends largely on the chemistry of the slag
available.
GGBS XF + calcium sulphate outperforms in all areas, achieving the highest
compressive and flexural strengths, and the most stable shrinkage
compensation. This is confirmed by the amount of ettringite formed found in
XRD analysis.
The research showed that fineness has a significant impact on result, which
can only in part be compensated by increasing the dosage.
In all cases it is essential to find the right equilibrium of all components in the
matrix.
Effects aimed to be achieved depend to a large extend to the type of raw
materials being used.

48. practical use
• Cement fiber panels
• GRC
• Pre-fabricated concrete
• 3D printing
• Winter concreting
• Dry-Mix
• Volumetric concrete

49. demolding of prefabricated concrete
• fast setting reactive binder
• no heating molds
• no increase ambient temperature
• high initial strength

50. demolding of prefabricated concrete
3d
3 D printing
• fast setting
• low alkali
• no volume hange
• high initial strength

51. • fast setting reactive binder
• working at low ambient
temperatures
• no addition of accelerators
• high initial strength
winter concreting

52. drymix
• stable reactive binder
• low carbon footprint
• reduction binder content
• fast setting
• initial strength
• compensation of shrinkage
• low alkalinity
• high density

53. VOLUMETRIC CONCRETE
• fast setting binder
• low carbon footprint
• reduction binder content
• high initial strength
• compensation of shrinkage
• low alkalinity
• high density