1. DSc(Eng) Prof. Pavel Krivenko
Workshop «Supmat»
Brno University of Technology
19 June, 2012 Brno, Czech Republic
ALKALI ACTIVATED CEMENTS –
A STEP TOWARDS TRUE
SUSTAINABLE DEVELOPMENT
DSc(Eng) Prof. Pavel Krivenko
PhD Elena Kavalerova
PhD Vit Petranek *
PhD Jiri Zach *
SUPMAT – Podpora vzdělávání pracovníků center pokročilých stavebních materiálů
Registrační číslo CZ.1.07/2.3.00/
Tento projekt je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
V.D.Glukhovsky Scientific Research Institute for Binders and Materials.
Kiev National University of Civil Engineering and Architecture, Vozdukhoflotsky pr. 31 Kiev Ukraine
* Faculty of Civil Engineering, Brno University of Technology Veveri 331/95, , Brno, Czech Republic

2. SUSTAINABLE DEVELOPMENT: DEFINITION
The term “sustainable development” was first defined in the Brundtland Report «Our common future», published in 1987, as follows:
“sustainable development” is a long-term development, which corresponds to the needs of the present-day generation without putting at risk the possibility of future generations to satisfy their own needs and to choose their own life style.
In 1992 the term was modified into “global sustainable development” and since then it includes three cornerstones, they are:
environmental protection
social
economical development

3. ENVIRONMENTAL PROTECTION
The environmental, in particular global warming, is caused by carbon dioxide (CO2) produced during consumption of solid, liquid and gaseous fuels

4. CEMENT PRODUCTION
Cement production is the THIRD largest cause of man- made carbon dioxide emissions.
During cement manufacturing, cement is calcined to produce calcium oxide. In the process, metric ton of CO2 is released for each ton of cement produced.

5. According to different estimates, the cement industry contributes between 2.5 to 5% to global anthropogenic CO2 emissions, thus making the cement industry an important sector for CO2 -emission mitigation strategies.
In the manufacture of cement the CO2 is emitted from
the calcination process of limestone
combustion of fuels in the kiln
power generation.

6. The world consumption of cement over the last 15 years is constantly increasing in average by 3.75 % per year. The most cement consumption regions are the developing countries in which the rates of growth are 10 % per year, for example The rates of cement consumption have increased in Europe in 2006 – by 3.8 %.
P.R. China – 9 %,
India – 8.9 %,
Philippines – 8.4 %,
Mexico – 3.4 %.

7. Atmospheric CO2 concentration (ppm) and world Portland cement production (million tons) for the time frame
The carbon emissions from fossil fuel combustion and cement production in 2005 were 7.9 Gt, 28% higher than in (Kyoto Protocol Base Year).

8. The industrialization of some highly populated countries is behind the acceleration in the rate of growth of CO2 emissions.
China has now surpassed Japan and is the second largest CO2 emitter after the United States.
China might surpass the U.S. as the largest CO2 emitter by Other growing developing countries, such as India and Brazil, are also fast becoming large emitters.

9. Thus, cement production touches on a wide range of sustainability aspects

10. PERSPECTIVE WAY TO FOLLOW: ALTERNATIVE CEMENTS
There exists a class of advanced cements with high potential with regard to carbon dioxide emissions because it is a cementitious material that does not require firing for its production and in most cases it does not need to include the OPC clinker.
As to investments into production of the alternative cements, such investments are so-called «socially responsible investments» (a term «socially responsible investment» (SRI) was introduced first at the Summit in Johannesburg in 2002 and such investments are relatively low ones compared to a CO2 tax burden on the ordinary Portland cement producers.

11. ALTERNATIVE CEMENTS
50 YEARS AGO (in 1957), a class of alkali activated cements appeared in the field in Kiev (Ukraine, USSR). These cements have a high potential with regard to carbon dioxide emissions because they do not require firing for their production and in most cases they do not need to use OPC clinker.

12. THEORETICAL BACKGROUND OF ALKALI ACTIVATED CEMENTS (AAC)
In 1957 Victor Glukhovsky (Kiev, Ukraine, USSR) made a discovery that alkali metal compounds - elements of the first group of the PERIODIC TABLE (Li, Na, K, Rb, Cs) - exhibit hydraulic binding properties similar to compounds of alkaline earth metals - the elements of the second group (Mg, Ca, Sr, Ba).
Prerequisites for exposing hydraulic binding properties
“OLD” THEORY
Restricted solubility
of initial solid phase
“NEW” THEORY
High solubility of one of the constituents of initial solid phase creating an alkaline reaction in an aqueous medium

13. Alkali activated cement (AAC)
DEVELOP A NEW CEMENTITIOUS MATERIAL THE HYDRATION PRODUCTS OF WHICH WOULD BE ANALOGUES TO NATURAL ZEOLITES
CaO-SiO CaO-SiO2-H2O
+H2O 
CaO-Al2O CaO-Al2O3-H2O
Ordinary Portland cement (OPC)
Al2O3-SiO R2O-Al2O3-SiO2-H2O
+ R2O + H2O 
RO-Al2O3-SiO RO-R2O-Al2O3-SiO2-H2O
Alkali activated cement (AAC)

14. TERMINOLOGY Soil cements Geopolymers Alkali activated cement F-cement
Gypsum-free Portland cement
SKJ-binder
Geocements
Alkaline cements
Glukhovsky, 1957
Davidovich, 1973
Narang, Chopra, 1983
Forss, 1983
Odler, Skalny, Brunauer 1983
Changgo, 1991
Krivenko, Skurchinskaya 1991
Krivenko, 1994

15. The most widely applied term
alkali activated cements
Published in 2006
by Taylor & Francis
www. tandf.co.uk/builtenvironment

16. EXAMPLES OF COMPOSITIONAL BUILD-UP OF AAC (REFERENCE- OPC)‏
4-8
Metallurgical
slag + R2O
Slag alkali activated
cement
10-20
5-10
2-5
1-5
< 0.6
Alkali content,
R2O, %
0% R2O-Al2O3-SiO2-H2O %
100 % RO-SiO2-H2O
Hydration product
Clay + R2O
Fly ash from heat power stations (product of coal combustion) + R2O
OPC clinker + additive (slag, ash, basalt) + Me2O
OPC
clinker + R2O
clinker
Initial solid phase
Geo-cement
Ash alkali activated
Blended alkali activated OPC
Alkali activated OPC
Cement Type
*R2O – Na2O, K2O, Li2O

17. AAC TYPES HIGH STRENGTH HIGH EARLY STRENGTH CORROSION RESISTANT
FIRE RESISTANT
HEAT RESISTANT
LOW HEAT OF HYDRATION

18. PRACTICAL APPLICATION: AAC CONCRETES
Heavy-duty road pavements. Access roads and disposal sites of chemical plants.
Binding material for radioactive waste immobilization.
2000
Inorganic adhesives and glues, protective coatings against action of corrosive environments and high temperatures
1990
Building products and structures from acid resistant concretes
High-rise building from precast- and cast-in-situ concrete
Bodies of precise machine tools
1985
Floors, landings from cast-in-situ concrete
Blocks for buildings, garages, storage houses, etc.
Moulds
1980
Building products and structures from hest resistant concretes
Floor slabs, foundation wall blocks, foundation blocks, piles
Oil well mortars and grouts
Linings of MD-pumps for Al melts
1975
Road bases from strengthened soils
1970
Tubing of anti-slide systems
Pavements from cast-in-situ concrete and precast reinforced concretes slabs
Pasture sites, disposal sites for fertilizes, silo pits from cast-in-situ and precast concrete
Foundation blocks, floor slabs, columns, beams, foundation wall blocks, etc.
Reinforced pit props, sleepers
1960
Sea breakwaters, elements of irrigation systems from cast-in-situ and precast pre-stressed concrete
Pedestrian way slabs, edges of pavement, landing field slabs
Hydraulic
Road
Agricultural
Industrial
Residential
Mining
Constructional engineering
Non- constructional engineering

19. AAM RESEARCH&DEVELOPMENT TEAM LOCATIONS

20. RILEM
(International Union of Laboratories and Experts in Construction Materials, Systems and Structures, France) (
The RILEM Technical Committee «ALKALI ACTIVATED MATERIALS» was created in 2007 to help with standardization of the AACs and AAC-based concretes around the world.
Task list for the RILEM TC « AAM» (Gent, Belgium, 2007):
standardization
recommendations on the use of aluminosilicate raw materials
recommendations on the fields of application
recommendations on testing procedures
recommendations on the manufacturing technologies
In 2012, this Committee will be transformed into two committees, one of which is a technical committee on durability testing of alkali activated materials.

21. AAC AND «BEST AVAILABLE TECHNIQUES»
Best Available Techniques (BAT) means the most effective and advanced stage in the development of activities and their methods of operation. Such BATs are suitable in principle to provide the basis for the setting of emission limit values.

22. AAC AND «BEST AVAILABLE TECHNIQUES»
BEST means most effective in achieving a high general level of protection of the environment as a whole
AVAILABLE means:
developed to a scale which allows implementation under economically and technically viable conditions;
reasonably accessible to the operator;
taking into account the costs and advantages.
The definition of "available" is of particular importance as the huge investments and long pay-back periods for process modifications make the cement industry very careful in selecting and developing new technologies.
TECHNIQUES means both technology and plant design construction, maintenance, operation and decommissioning.

23. AAC AND «BEST AVAILABLE TECHNIQUES»
Determination of BAT with regard to cement production includes consideration of costs/benefits and cement specific items as follows:
Use of «low waste» technology
Recovery and recycling of own process waste or of waste generated elsewhere
Technological advances and changes in scientific knowledge and understanding.
Nature, volume, effects of emissions concerned.
Length of time needed to introduce BAT.
Process energy efficiency.

24. BENEFITS
Proofs have been collected that in solving the environmental & energy saving problems the alkali activated cements are highly advantageous over Portland cements

25. DURABILITY Cement Type Early strength Durability Chemical resistance
Portland cement ++ +
Blended cement
+++
High alumina cement
High sulfate cement
Sulfoaluminate cement
Alkali activated cement
(+) - low, (++) - medium, (+++) -high

26. Stoichiometric formula
DURABILITY
Cement
Hydration products
Solubility, kg/cub m
Mineral
Stoichiometric formula
Slag AAC
CSH(B)
Xonotlite
Riversideite
Plombierite
Gyrolite
Calcite
Hydrogarnet
Na-Ca hydrosilicate
Thomsonite
Hydronepheline
Natrolite
Analcime
5CaO SiO2 nH2O
6CaO 6SiO2 H2O
5CaO 6SiO2 3H2O
5CaO 6SiO2 10.5H2O
2CaO 3SiO2 2.5H2O
CaCO3
3CaO Al2O3 1.5SiO3 3H2O
(Na,Ca) SiO4 nH2O
(Na,Ca) Si2O3 Al2O3 6H2O
Na2O Al2O3 2SiO2 2H2O
Na2O Al2O3 3SiO2 2H2O
Na2O Al2O3 4SiO2 2H2O
0.05
0.035
0.050
0.051
0.014
0.02
OPC
Calcium hydroxide
C2SH2
Tetracalcium hydroaluminate
Tricalcium hydroaluminate
Hydrosulfoaluminate
Ca(OH)2
2CaO SiO2 nH2O
5CaO 6SiO2 nH2O
4CaO Al2O3 13H2O
3CaO Al2O3 6H2O
3CaO Al2O3 3CaSO4 .31H2O
1.3
1.4
1.08
0.56
high

27. ENVIRONMENTAL BENEFITS OF THE AAC PRODUCTION
CONSERVATION OF NATURAL RESOURCES
This is in line with the requirements of global sustainable development.
PROTECTION OF AIR, GROUNDWATER AND SOIL
Waste materials diverted from landfills will not generate harmful gaseous emissions or liquid effluents thus reducing the risk of contamination.
GREENHOUSE GAS REDUCTION
The AAC production does not require burning thus contributing a lot in energy saving.

28. Brand of cement (Strength class)*
Energy saving
Brand of cement (Strength class)*
OPC
Slag OPC
Slag ACC
Specific fuel, kg
300
400
500
600 -
280
291
345
140
163
194 40 45 50 55
Electric energy, KW∙h
150
100 41 56
* Strength class (or compressive strength at 28 days age in kgf/cm2), according to Ukrainian standards for cement.

29. THE AAC PRODUCTION SCHEME
1 – blending bed for slag; 2 – blending bed for clinker (if any); 3 – dust collector; 4 – belt conveyer; 5 – vertical roller mill; 6 – bag filter; 7 – metering equipment for admixture; 8 – heat generator for drying; 9 – elevator; 10 – silos for cement constituents; 11 – bunker for additives and alkaline activator; 12 – mixer for dry cement constituents; 13 – ready product storage silo; 14 – packer for bags; 15 – palletizer.

30. OPC PRODUCTION SCHEMES

31. SOCIO-ECONOMIC BENEFITS
Reduction of Disposal Fees
Since only moderate investments are needed, the AAC plants can recover adequate wastes at the lower costs than would be required for landfilling.
Investments in Clean Technologies
Substituting materials derived from waste streams usually reduce the production cost in cement manufacturing, thus strengthening the position of the industry particularly with regard to imports from countries with less stringent environmental legislation. It will also facilitate the industry’s development of technologies to further clean up atmospheric emissions. Thus, the AAC production meets a requirement as to «CLOSED CYCLE ECONOMIES» of the future.

32. CONCLUSIONS
The alkali activated cements can be produced using the BAT.
The alkali activated cements with their high environmental potential are a vital alternative to the existing Portland cements;
The alkali activated cements being low energy- consuming cements, are highly advantageous materials in terms of global sustainable development (sustainability);
The alkali activated cements fall successfully within the CO2 emissions trading scheme under the Clean Development Mechanism (Certified Emissions Reductions) under the Kyoto Protocol;
The alkali activated cements can be considered as cements without omitting CO2.

33. Thank you for attention!