Download - Metacal-metakaolin
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CAL
METAKAOLIN
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Introduc2on
Al2O(SiO2)2 (H2O)x+ (2-‐x)H2O (metakaolin)
grinding / pelle:zing
rotary kiln calcina:on (5h 750°C)
+ ground
KAOLINITE (kaolin) �aluminium silicate
Al2O3 (SiO2)2 (H2O)2
METAKAOLIN �
finely ground +
flash calcina:on method (few seconds 750°C)
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two types
off white pink colored white colored
rotary kiln calcina:on
round shaped plate structure
flash calcina:on
CAL
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Through FLASH CALCINATION metakaoline turns to round beats , whereas a plate structure is obtained in tradi:onal produc:on
1 μm 0,5 μm
0,5 μm 0,5 μm
Kaolin �
Metakaolin �
Flash calcina2on Rotary kiln
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Al203 40~45 % SiO2 30~55 % Blaine > 12,000 gm2/g Average par:cle size 1 μm Density 2,6 Shape plate to round structure
average composi2on
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According to the La Chapelle test both types have the same lime binding factor ~1300 gr of lime per 100 gr of metakaolin
Chapelle test
Comparision of puzzolanic reac:vity (Chapelle)
Materials Puzzolanic reac:vity mgCa(OH)2/g
blast furnace slag 40
eco-‐binder 306
silica fume 427
calcined bauxite 534
fly ash 875
CAL 1205
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Al2O3·∙(Si2O2)2+CH+H
METAKAOLIN calcined at proper temperature brings a highly reac:ve pozzolanic material which reacts with calcium hydroxide (CH) higher temperature leads to recrystalliza:on and reduc:on of reac:vity and converts to an inert filler
CSH + C4AH13 and C3AH6 (hydrated calcium aluminates ) +C2ASH8= gehlenite hydrate or stratlingite (incorpora:on alkali)
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METAKAOLIN will accelerate the se`ng of cement. As it reacts with the lime released during hydra:on of Portlandcement , the C3A content will go in solu:on quicker. It reduces the pH whereby the stratlingite (C2ASH8) will incorporate hydroxide and chloride ions in its structure In :me more portlandite is formed leading to higher strengths and durability. It is about 10 :mes finer than Portlandcement giving the matrix beder compac:on fewer pores and smaller pore size.
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prevents fading of colours
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prevents lime bloom
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reduc:on of cracks and voids
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improved impermeabilty – reduced risk of ASR and
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resistant to sulfate adack and (de-‐icing) salts preven:on of spalding
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No CO2 produc:on according to the chemical reac:on Low temperature of the process 750 °C
Consump:on of energy 2900 MJ/tonne CO2 produc:on 150 kg/tonne
environment
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• increased cost price • higher water ra:o • workability • addi:onal raw material • at low addi:on rate increase shrinkage
dis advantages
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Mortars,GRC and concrete manufactured with Metakaolin will exhibit the following benefits; ü increased compressive and flexural strength ü improved durability ü reduced permeability ü reduced efflorescence ü increased chemical resistance ü reduced chloride migra:on ü increased viscosity ü enhanced workability and finishing ü reduced effects of alkali-‐silica reac:vity (ASR) ü increased adhesion ü reduced shrinking ü lighter color ü reduc:on of CO2
advantages
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ü reduced alkali – GRC applica:on – protec:on of AR glass ü forma:on of secondary C-‐S-‐H ü elevated elas:c modulus (EMR) ü less pores ü smaller pore size ü improved early and late strength cement and lime ü consistent color ü color sustainability ü low risk on lime -‐ bloom ü produc:on of hydraulic lime through blending ü geo-‐polymers ü It improves the density of the cement matrix through its fineness and
the reac:on with CH See more at:
www.caltra.com
further advantages