1. 1 V.D.Glukhovsky Scientific Research Institute for Binders and Materials, Kiev National University of Civil Engineering and Architecture, Vozdukhoflotsky pr., 31 Kiev 03680 Ukraine e-mail: pavlo.kryvenko@gmail.com Letni Skola SUPMAT 17-23 June 2013 Brno, Czech Republic

2. 2 1.Fly ash- containing cementitious materials. 2.Methods of activation of fly ash. 3.Specific features of different types of alkaline activation of fly ash: - pure alkaline activation; - mixed sodium/calcium activation. 4. Studies on alkali activated fly ashes modified with Ca-containing additives (1-10% by mass). 5.Conclusions.CONTENTS

3. 3 By the beginning of the XXI century a worldwide cement production has reached 1.7 billion tons. Portland cement is a highly energy consuming material: 1 ton of it requires 700…1300 Mcal of heat power and 90…130 kWh of electric power. Atmospheric pollution: during production of 1 ton of portland cement clinker 900 kg of CO 2 and other greenhouse gases are released, constituting 5…7% of the total worldwide emissions. “Global Sustainable Development Concept” requires, among many other things, to preserve natural resources, whereas 1 ton of portland cement requires 4…5 tons of natural raw materials. CEMENT PRODUCTION AND GLOBAL SUSTAINABLE DEVELOPMENT

4. 4 METHODS OF HOW TO REDUCE ENVIRONMENTAL IMPACT OF CEMENT PRODUCTION Use of alternative fuels Alternative raw materials for OPC clinker production HIGH-VOLUME REPLACEMENT BLENDED CEMENTS Low energy- consuming clinkers (belite PC, etc.) Others To substitute OPC clinker with supplementary materials Pozzolanic waste materials are the most commonly used supplementary materials

5. 5 FLY ASH- CONTAINING CEMENTS FLY ASH Class CClass F CaO < 10% S+A+F > 70% no any hydraulic activity in standard conditions CaO > 10% S+A+F < 50% increased content of sulfates weakly reacts with water in standard conditions EN 197 includes TWO types of cements containing fly ash: portland fly ash cement CEM II (21…35% of fly ash) pozzolanic cement CEM IV (36…55% of fly ash).

6. 6 HYDRATION OF FLY ASH- CONTAINING CEMENTS In fact, the fly ash content in the cement composition does not usually exceed 30 %, because of low level of activation (the main problem is low rate of hardening) Peculiarities of hydration of fly ash-containing cements are generally attributed to a pozzolanic reaction: Ca(OH) 2 is bound by amorphous silica and alumina with the formation of additional amounts of calcium silicate or alumosilicate hydrates. Advantages: the lower heat evolution; improved chemical and corrosion resistance; decreased leachability and improved resistance to efflorescence; reduced environmental impact and improved sustainability. Disadvantages: the lower rate of hardening and low initial strength; the lower mechanical strength (in case of increased fly ash content); durability problems due to increased content of sulfates (in fluidized ashes); sensitivity to overdosage of fly ash.

7. 7 METHODS OF ACTIVATION OF FLY ASH (FA) ACTIVATION OF FLY ASH CHEMICALMECHANICALTHERMAL alkalinesulfate alkaline earth alkaline-alkaline earth alkali ash-containing OPC (Types II and IV), ash lime-binder (C-A-S-H) ash-containing sulfate cement, silica-modified (C-A-S*-s-H) alkali activated fly ash cements (N-C-A-S-H) geocements/ fly ash-based geopolymers (N-A-S-H) sulfates alonesulfate-silica ash-containing sulfate cement (C-A-S-s-H)

8. 8 FLY ASH CONTENT OF DIFFERENT CEMENTS 0102030405060708090 Max fly ash content, % OPC type II OPC type IV FA-sulfate-silica cement Alkaline-alkaline earth activated cement Alkali activated cement

9. 9 Limit of R 2 O content in OPC CaO, % Na 2 O, % 2 4 6 8 10 2 5 20 5075100 12 5 6 4 3 2 1 0 OPC Alkali Activated Slag Cements Alkali- Alkaline Earth Activated Fly Ash Cements Alkali Activated Portland Cements Alkali Activated Fly Ash Cements ALKALINE vs. ALKALINE EARTH ACTIVATION Lime

10. 10 TYPES OF ALKALINE ACTIVATION Common cements of strength class 42.5 can be obtained with FA content of 70% Alkaline - alkaline earth activated cementsAlkali activated cements (geocements/geopolymers) R-C-A-S-H R-A-S-H - structure formed: C-S-H and R-A-S-H gels; - fly ash particles are partially activated by alkalis at early stages of hardening; - alite hydration is slower; - neither portlandite, nor ettringite appear. - structure formed: R-A-S-H gel with zeolite inclusions depending on type of curing; - fly ash particles are well activated by alkalis (over 50 %); - thermal curing (45-150˚C) of up to 8 hrs is required. Cements and coatings for special use (heat and acid resistant), matrices for immobilization, etc. ALKALINE DISPERGATION INTERACTION/ COAGULATION CONDENSATION/ CRYSTALLIZATION

11. 11 CEMENT COMPOSITION DESIGN R-C-A-S-HName Content of oxides, % by mass LOI, % SiO 2 TiO 2 Al 2 O 3 Fe 2 O 3 FeOMnOMgOCaO Na 2 O K2OK2OK2OK2O P2O5P2O5P2O5P2O5 SO 3 Fly ash of hydroremoval (No 1) 47.01 0.97 17.04 17.12 8.15 0.23 1.41 3.05 0.48 1.60 0.32 0.06 2.47 Fly ash of dry removal (No 2) 48.20 0.89 19.65 4.50 3.15 0.11 1.36 2.18 1.04 2.78 0.02 0.11 16.02 Fly ash of dry removal (No 3) 50.94 0.94 24.56 13.25 - 0.03 1.98 2.86 0.69 2.69 0.02 - 1.36 Fly ash of hydroremoval (No 4) 39.99 1.04 13.85 12.86 0.02 1.96 3.54 1.40 2.30 0.19 0.38 0.18 21.86 Portland cement PC І-500 (No 5) 23.40 - 5.17 4.12 -- 0.88 64.13 0.41 0.33 - 0.55 0.20 Granulated blast furnace slag (GGS) (No 6) 39.40 0.26 6.80 - 0.32 5.19 47.38 0.60 0.52 - 1.62 - Raw materials

12. 12 CHARACTERISATION OF RAW MATERIALS Q–β-quartz Н–hematite М–mullite L–larnite Wо–wollastonite Мr–merwinite Не–gehlenite А–alite В–belite F–tetracalcium aluminoferrite No 1 No 2 No 3 No 4 No 5 No 6 No 5 No 6 No 5 No 6 No 5 No 2 No 1 No 3 No 4 No 1 No 3 No 4 No 1 No 3

13. 13 Strength development of cements PHASE COMPOSITION OF HYDRATION PRODUCTS AND PROPERTIES OF CEMENTS 1 2 3 4 1 2 3 4 4 3 2 1 4 3 2 1 X-ray and DTA examination of the alkali activated fly ash cements hardened for 28 days in standard conditionsNos CEMENT COMPOSITION, % BY MASS Properties Flow (cone), mm W/C PORTLAND CEMENT CLINKER ASH No 3 GBS Na 2 CO 3 PLASTICIZER Paste of normal consistency, % Initial setting time, min 1-604051 25.7 75115 0.34 210603051 25.5 70112 0.34 32080-51 26.7 80108 0.31 43070-51 26.0 75110 0.32 5 CEM ІІ/А-400 27.8 85 112 112 0.38 СSН (В) (d = 0.304; 0.299; 0.281; 0.203; 0.18 nm) (d = 0.188; 0.273; 0.274; 0.418 nm) (d = 0.424; 0.334; 0.245; 0.212 nm) Ca 2 Al 2 Si 2 O 8 ⋅ 4H 2 O β-SiO 2 NaCa 2 [Si 3 O 8 (ОH)] (d = 0.290; 0.274; 0.192 nm)

14. 14 soda ash (5 % by mass) sodium metasilicate (5% by mass) sodium metasilicate (6% by mass + soda ash (4 % by mass) IMAGES OF CEMENT SPECIMENS AGED 28 DAYS TAKEN USING A SCANNING ELECTRON MICROSCOPE

15. 15 COMPRESSIVE STRENGTH OF THE ALKALI ACTIVATED FLY ASH CEMENTS VS. (SiO 2 + Al 2 O 3 ) CONTENT OF FLY ASH Characteristic No 4 No 2 No 1 No 3 SiO 2 + Al 2 O 3, % 53.84 60.66 75.24 75.91 Soda ash (5 % by mass) 24.60 28.70 28.70 35.00 40.90 а) Soda ash (5 % by mass) b) Sodium metasilicate (6 % by mass) + soda ash (4 % by mass) Cement compressive strength (28 days) vs. content of (SiO 2 + Al 2 O 3 ) of fly ash Strength development vs. type of alkaline activator

16. 16 COMPRESSIVE STRENGTH OF THE ALKALI ACTIVATED FLY ASH CEMENTS VS. TYPE OF ALKALINE ACTIVATOR Compressive strength of cement stone vs. type of alkaline activator Compressive strength of cement stone vs. content of soda ash 0 5 10 15 20 25 30 35 40 45 Compressive strength, MPa 2728Steam curing Age, days Soda ash 5% Na-metasilicate 5% SA (4%)+SMS (6%)

17. 17 BASIC PROPERTIES OF THE ALKALI ACTIVATED FLY ASH CEMENTS VS. PLASTICIZER Initial setting time vs. рН-value of plasticizer and its quantity BASIC PROPERTIES OF THE ALKALI ACTIVATED FLY ASH CEMENTS VS. VARIATIONS IN CEMENT COMPONENTS Cement composition, % by mass Cement paste Flow value (cone), mm W/C Strength, Rcomp/Rflex, MPa, after hardening for CaO-containing additive FA No3 FA No3 Soda ash plasticizer Paste of normal consistency, % Initial setting time, min 2 days 7 days 28 days steam curing (80°С) 30 (portland cement clinker) 7050.7526.01-021100.322.001.0919.44.9 40.5 6.4 28.4 6.27 30 (PC І-500) 7050.7526.01-301060.344.121.4420.65.8 41.1 6.95 21.4 5.22 10 (portland cement clinker) 30 (gbs) 6050.7526.31-101070.334.081.0824.45.9 39.4 7.15 26.5 5.64 10 (PC І-500) 30 (gbs) 6050.7525.01-201120.345.401.2025.56.43 42.9 8.29 23.2 5.26 Specific heat evolution of the cement “fly ash No3– portland cement clinker – sods ash – water repellent agent” vs. рН of plasticizer

18. 18 ISOPARAMETRIC DIAGRAMS OF COMPRESSIVE STRENGTH VARIATIONS OF THE ALKALI ACTIVATED FLY ASH CEMENTS (fly ash No 3) VariableFactors Content of soda ash, % by mass Fineness of fly ash (expressed as specific surface by Blaine), m 2 /kg Content of plasticizer, % by mass The lower level “-1” 3600 0.500.500.500.50 Basic level “0” 5 700 0.75 The upper level “+1” 7800 1.00 Factors and levels of variables The alkali activated cement “fly ash-portland cement-soda ash” hardened for 28 days in standard conditions

19. 19 COMPRESSIVE STRENGTH VARIATIONS OF THE CEMENT “fly ash No3 – portland cement – gbs - alkaline activator” hardened for 28 days in standard conditions Optimal compositions of the alkali activated fly ash cements Fly ash No3, % by mass PC І-500, % by mass GBS, % by mass Soda ash, % by mass Plasticizer, % by mass Alkali activated pozzolanic cement 66.2 28.4 - 4.74.74.74.7 0.70.70.70.7 Alkali activated composite cement 56.7 9.59.59.59.5 28.4 4.74.74.74.7 0.70.70.70.7

20. 20 Cement type DesignationType Cement compoition, % by mass Aluminosilicate component Alkali metal compounds (Na or K) ** Granulated blast-furnace slag, S OPC clinker* CL Fly ash, FA Basalt, B 12345678 ЛЦЕМ I Alkali activated slag cement ЛЦЕМ I 90-1000-10-- 1.5-12 Alkali activated slag cement with additive of fly ash ЛЦЕМ I -З 55-900-1010-35- 1.5-12 ЛЦЕМ II Alkali activated portland cement ЛЦЕМ II -100-- 1.5-12 ЛЦЕМ III Alkali activated pozzolanic cement ЛЦЕМ III-З 36-80- 1.5-12 ЛЦЕМ III -Б -36-80 ЛЦЕМ IV Alkali activated slag portland cement ЛЦЕМ IV 36-8911-64-- 1.5-12 ЛЦЕМ V Alkali activated composite cement ЛЦЕМ V 30-505-1040-65- 1.5-12 ALKALI ACTIVATED CEMENT TYPES AND COMPOSITIONS * For the alkali activated slag cements designated as ЛЦЕМ I, ЛЦЕМ I –З, ЛЦЕМ-V, it is allowed to replace OPC clinker with portland cement of Type I – OPC I. ** Content of alkali metals, given in Table is taken over 100% of a sum of the aluminosilicate components. ЛЦЕМ I–alkali activated slag cements (from 55 to 100% granulated blast-furnace slag), strength classes 300, 400, 500, 600,700, 800, 900, 1000. ЛЦЕМ II – alkali activated portland cements (100 % OPC clinker), strength classes 300, 400, 500, 600,700, 800, 900, 1000; ЛЦЕМ III – alkali activated pozzolanic cements (from 36 to 80 % ash or basalt), strength classes 300, 400,500. ЛЦЕМ IV–alkali activated slag portland cement (from 36 to 89% granulated blast-furnace slag), strength classes 300, 400, 500, 600, 700. ЛЦЕМ V – alkali activated composite cements (from 90 to 95% of total content of granulated blast-furnace slag and ash), strength classes 300, 400, 500, 600,700, 800, 900, 1000.

21. 21 HEAT EVOLUTION OF THE ALKALI ACTIVATED FLY ASH CEMENTS Specific heat evolution of the alkali activated fly ash cements Specific heat evolution of the alkali activated composite cement ЛЦЕМ V-400 vs. alkaline activator Specific heat evolution of the alkali activated composite cement ЛЦЕМ V-400 with various fly ashes (designation from page 11) Specific heat evolution of the alkali activated composite cement ЛЦЕМ V-400 vs. alkaline activator content (soda ash) 1- “fly ash No3 – portland cement – soda ash – water repellent agent”; 2 – “fly ash No3 – portland cement – gbs – soda ash – water repellent agent”; 3- “fly ash No3 –gbs– soda ash – water repellent agent”; 4 – CEM ІІІ/А-400

22. 22 CORROSION RESISTANCE OF THE ALKALI ACTIVATED FLY ASH CEMENTS Nos Cement type (alkaline activator - soda ash) Coefficient of resistance after storage in the solutions after 12 months in in aggressive environments sea salt, 18 g/l 5%-Na 2 SO 4 10%-Na 2 SO 4 2%-MgSO 4 4%-MgSO 4 1 “fly ash No3 – portland cement – soda ash – water repellent agent” 0.95 1 1.45 0.90.90.90.9 0.74 2 “fly ash No3 – gbs – portland cement – fly ash – water repellent agent” 1.39 1.15 1.41.41.41.4 1.18 1.06 3 CEM ІІІ/А-400 1.05 0.88 0.80.80.80.8 0.77 0.71

23. 23 CORROSION RESISTANCE OF THE ALKALI ACTIVATED ASH CEMENTS Appearance of the fine aggregate concrete samples after 18 months in aggressive environments Sea salt Na 2 SO 4 – solution (5% concentration) Na 2 SO 4 - solution (10% concentration) MgSO 4 - solution (2% concentration) MgSO 4 - solution (4% concentration)

24. 24 EXAMPLE OF APPLICATION: IMMOBILIZATION OF Pb Additive: OPC After curing in a covered mould * Studied in accordance to EDV-S4 method. Initial Pb content was 1% by mass. 0 2 4 6 8 10 12 14 16 Pb concentration in solution, mg/l 0110(OPC) Composition (% additive) Cur. Covered mould Steam curing 0 2 4 6 8 10 12 14 16 Pb concentration in solution, mg/l OPC 10%Slag 10%(OPC) Composition (additive + %)

25. 25CONCLUSIONS THE FLY ASH CONTENT CAN REACH IN THE CEMENT COMPOSITION OF 70% IN CASE OF ALKALINE ACTIVATION TO BE APPLIED. THESE CEMENTS HAVE HIGH POTENTIAL FOR MAKING CORROSION RESISTANT CONCRETES. THESE CEMENTS ARE LOW HEAT CEMENTS AND CAN BE SUCCESSFULLY USED IN MASS CONRETING. THESE CEMENTS CAN BE USED IN IMMOBILIZATION OF TOXIC WASTES. THESE CEMENTS HAVE HIGH MECHANICAL STRENGTH CHARACTERISTICS (60- 80 MPa).

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