Fly ash in cement and concrete composition Zbigniew Giergiczny Silesian University of Technology, Gliwice, Poland Technological Center Betotech, Ltd. April, 24– , Moscow

Subject of presentation Definition of fly ash Classification of fly ash Fly ash as a cement component Fly ash as an additive for concrete Summary Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash Fly ash – is one of the residues resulted from hard coal or brown coal dust combustion in various types of furnaces in the power or heat and power plants. FLY ASH Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Classification of fly ash Fly ash can be classified according to: chemical composition, amorphous and crystalline phase content, fineness (sieve residue), unburned carbon content (loss on ignition). Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Classification of fly ash FLY ASH SILICEOUS SILICEOUS - ALUMINOUS CALCAREOUS (siliceous - calcareous) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash as a cement component Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash according to cementitious standard EN Fly ash is obtained by electrostatic or mechanical precipitation of dust-like particles from the flue gases of furnaces fired with pulverised coal. The ash obtained by other methods should not be used in the cement according to EN Siliceous fly ash (V) is a fine powder of mostly spherical particles having pozzolanic properties. It consists essentially of reactive silicon dioxide (SiO 2 ) and aluminium oxide (Al 2 O 3 ). The remainder contains iron oxide (Fe 2 O 3 ) and other compounds. Requirements: reactive calcium oxide (CaO) max. 10,0 % reactive silicon dioxide content min. 25,0 % content of loss on ignition (unburned carbon): cat. A ≤ 5,0 %, cat. B ≤ 7,0 %, cat. C ≤ 9,0 %. Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Siliceous fly ash (V) Spherical grains of a high content of the glassy phase High fineness ( specific surface area from to m 2 /kg ) Pozzolanic properties Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Very fine powder having pozzolanic properties and/or hydraulic, It consists of reactive calcium oxide (CaO ≥ 10 %), silicon dioxide (SiO 2 ) and aluminium oxide (Al 2 O 3 ). The remainder contains iron oxide (Fe 2 O 3 ) and other compounds, It contains more phases than siliceous fly ash. Calcareous fly ash (W) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash with high content of calcium compounds POZZOLAN-HYDRAULIC ACTIVITY OF CALCAREOUS FLY ASH FROM CONVENTIONAL FURNACES Temperature [°C] Time of hydration [days] Specific surface of grund fly ash [m 2 /kg] Compressive strength [MPa] after: 3 days7 days28 days90 days 5593,42,45,2 7449,39,911,513,8 A 1 – unground ash A 2 – ground ash Time [days] Compressive strength [MPa] 70 % of siliceous fly ash (specific surface 540[m 2 /kg] 70 % of calcareous fly ash (specific surface 556[m 2 /kg] Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Characteristics of fly ash Morphology of fly ash grains calcareous siliceous Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Common cements contain fly ash as a main component 1) Most often this type of cement includes fly ash and blastfurnace slag, but also may include pozzolan, silica fume, burnt shale and ground limestone. 2) The cement includes usually a mixture of pozzolans and fly ash or fly ash. 3) The cement includes pozzolans, blastfurnace slag and siliceous fly ash. Type of common cement The content of mineral constituent, % mass Portland-fly ash cement CEM II/A-V CEM II/B-V CEM II/A-W CEM II/B-W Portland-composite cement 1) CEM II/A-M CEM II/B-M Pozzolanic cement 2) CEM IV/A CEM IV/B Composite cement 3) CEM V/A CEM V/B Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Properties of cements containing fly ash Setting time of CEM II/B-V 32,5R depending on ambient temperature Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Increase of compressive strength Zbigniew Giergiczny. V International Conference ASHES FROM TPPS Properties of cements containing fly ash

Compressive strength development of cements (standard mortars) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Pozzolanic activity Pozzolanic reaction rate depends on: chemical and mineral composition of fly ash, temperature and time of reaction, pressure, amount of water, fly ash / Ca(OH) 2 ratio, fly ash specific surface, presence of chemical admixtures FLY ASH (reactive SiO 2 and Al 2 O 3 ) Ca(OH) 2 hydrated calcium silicates (C-S-H) hydrated calcium aluminates hydrated calcium sulfo aluminate H2OH2O Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Amount of Ca(OH) 2 in hardened cement paste Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

CEM I 32,5R CEM III/A 32,5N Permeability of concrete CEM II/B-S 32,5R CEM II/B-V 32,5R Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Chemical composition of calcareous fly ash Specimen No Chemical composition [%] loss on ignition SiO 2 Al 2 O 3 Fe 2 O 3 CaOCaO w MgOSO 3 K2OK2ONa 2 O PL W1-0’2,5633,6219,275,3931,322,871,854,500,110,31 PL W4-0’2,6745,1720,794,5820,601,181,492,960,190,23 PL W5-0’3,5838,6327,926,6219,010,761,901,570,160,14 ST 20082,9142,9417,244,3125,891,402,043,470,260,13 P 342,0141,2716,544,5928,473,001,453,400,250,23 P 351,6334,3815,854,7433,552,531,615,840,270,29 P 361,5928,7114,724,6536,351,201,729,680,280,45 P 133,8734,3513,143,7837,145,161,763,380,190,33 P 333,6056,9018,203,1714,110,950,941,600,140,11 P 86,1128,709,764,0043,425,011,743,030,130,22 Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Phase composition of calcareous fly ash Mineral constituent Phase composition [%] PL W1-0'PL W5-0'PL W4-0'ST 2008P34P35P36P13P33P8 Amorphous phase30,664,448,658,720,026,552,43,142,039,1 Quarz SiO 2 11,66,316,810,324,311,34,211,131,95,0 Mullite Al 6 Si 2 O 13 2,35,64,42,43,82,21,42,36,52,2 Free CaO5,01,21,61,44,56,33,37,20,96,4 Anhydrite CaSO 4 5,51,83,94,55,08,910,44,01,43,1 Larnite 2CaO · SiO 2 12,81,94,04,214,416,411,617,84,221,2 Gehlenit Ca 2 Al 2 SiO 7 10,56,85,65,29,49,35,17,83,76,1 Anorthite CaAl 2 Si 2 O 8 8,95,911,18,48,06,12,06,06,43,4 Ca 3 Al 2 O 6 6,41,62,42,26,06,94,88,11,59,3 Hematite α-Fe 2 O 3 1,71,2 0,60,91,41,20,80,50,6 Brownmillerite Ca 2 (Al,Fe) 2 O 5 1,32,0 0,13,13,72,23,20,63,0 Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Pozzolanic activity of mineral additives + - ground components Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Compressive strength of Portland – composite cement - cements industrially produced Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Production scheme of CEM II/B-M (V-W) 32,5R Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Compressive strength of CEM II/B-M(V-W) 32,5R Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Results of conducted research Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

SILICEOUS FLY ASH AS A CONCRETE COMPONENT

Chemical composition of fly ash according to EN Component Allowed content Fly ash received from coal combustion only Fly ash received from co-combustion only Loss on Ignition  category A  category B  category C  5,0 % ≤ 7,0 % ≤ 9,0 % Chlorides  0,10 % SO 3  3,0 % CaO free  1,5 % 1) CaO reactive  10,0 % SiO 2 reactive Determination of the content is not necessary It is assumed that the requirement has been met ≥ 25,0 % Sum of oxides: SiO 2, Al 2 O 3, Fe 2 O 3  70,0 % Content of MgO  4,0 % Sum of alkalis expressed in Na 2 O eq  5,0 % Content of soluble phosphate compounds expressed in P 2 O 5  100mg/kg 1) Fly ash, in which the free CaO content is higher than 1.5% by mass may be accepted provided the soundness - Le Chatelier's test at ≤ 10 mm Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Phisical properties of fly ash according to EN PropertyRequirement Fineness, sieve residue with 0,045 mm of mesh sieve acc.to PN-EN  category N  category S  40 %  12 % Pozzolanic activity index: after 28 days after 90 days  75 %  85 % The soundness (test necessary when content of CaO free below 1,5 % max. 10 mm Consistent density Maximum difference  200 kg/m 3 compared to the one declared by the producer Initial setting time of paste containing 25% of fly ash and 75% of Portland cement CEM I Not longer that 120 minutes compared to the setting time of applied Portland cement CEM I Water demand (determined for fly ash of S category)  95% of water demand of Portland cement CEM I used in tests Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Property ASTM C618CAN/CSA –A Class FClass CClass FClass CIClass CH Total content of CaO≤ 10%≥ 10%≤ 8%8 – 20% ≥ 20% Loss on ignition, maximum, %6*126 Fineness (sieve residue 45 μm), maximum, % 34 Water demand, maximum, %105% – SO 3 content, maximum, %5 Oxides sum content (SiO 2, Al 2 O 3, Fe 2 O 3 ) > 70%> 50%-- - Activity index after 7 and 28 days75%**68%** Autoclave soundness, %0,8 *- it is allowed till 12% under the condition of suitability verification ** - can not be compared because of the different compositions of mortars fineness and density of fly ash can vary by up to 5% of the declared value Requirements set against fly ash in the standards ASTM and CAN-CSA Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash Fly ash Loss on ignotion – 1,79 % - category A Loss on ignotion – 8,48 % - category C Fineness – 1,0 % - category S Fineness – 27,5 % - category N Microscope image of fly ash Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Correlation of water demand and fineness of fly ash with similar loss on ignition (4,78% and 4,99%) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Correlation of water demand and loss on ignition of fly ash with similar fineness (30,6% and 29,8%) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Fly ash with different contents of loss on ignition (unburned carbon) Type of fly ashSlump test [cm] Amount of superplasticizer [% mass of cement] Air content [%] Fly ash I (2,2% loss on ignition) 18 cm0,871,7 Fly ash II (17,9% loss on ignition) 18 cm2,11,7 Fly ash – loss on ignition 2,2% Fly ash – loss on ignition 17,9% Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Effect of fly ash particle size on the amount in concrete mixing water at constant consistence [acc. Lindon K.A. Sear] Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Concrete with the addition of fly ash Lower total porosity Lower share of the capillary pores Larger share of the gel pores Microstructure Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

The diffusion coefficient of chloride ions in the concrete with fly ash and slag cements Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Frost resistance of concrete (F150); start test after 28, 56 and 90 days Cement (30% of fly ash); 350 kg/m 3 ; w/c = 0.5 Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

The change in temperature inside of the concrete block (volume 15 m 3 ) Zbigniew Giergiczny. V International Conference ASHES FROM TPPS

Conclusions 1.Fly ash, as a by-product of coal combustion, is an interesting mineral additive which should be widely applied in industrial practice, specially, in the production of cement and concrete 2.Used in the production of cement and concrete shall comply with the following standards: – PN-EN „Cement — Part 1: Composition, specifications and conformity criteria for common cements” – PN-EN 450 „Fly ash for concrete — Part 1: Definition, specifications and conformity criteria” 3.Fly ash applied in the above technologies should be characterized by: homogeneity, stability of physical characteristics, appropriate activity and spherical shape of the grains

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