Cements based on kaolinite waste
The cement industry involves high-energy consumption that generates high CO2 emissions into the atmosphere. Environmental concerns can be addressed by replacing parts of Portland cement clinkers with pozzolanic materials in mortars and concrete. Slag, fly ash and silica fume are materials considered...
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Veröffentlicht in: | Advances in geosciences 2018-08, Vol.45, p.133-138 |
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Sprache: | eng |
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Zusammenfassung: | The cement industry involves high-energy consumption that
generates high CO2 emissions into the atmosphere. Environmental
concerns can be addressed by replacing parts of Portland cement clinkers with
pozzolanic materials in mortars and concrete. Slag, fly ash and silica fume
are materials considered for the planned replacement. Research studies on
clay minerals, such as kaolinite, are being followed with special attention
by the scientific community and the cement industry. It is well known that these
minerals require an activation process to transform kaolinite (K) into
metakaolinite (MK). MK is an amorphous material from the transformation of K
with high pozzolanic activity, which is its capacity to react with the
portlandite released during the hydration of Portland cement, generating
compounds such as C–S–H gels and some aluminum-phase hydrates. One of the MK
production methods is heat treatment controlled by kaolinite at
temperatures in the range of 600–900 ∘C. Different residues have been used (coal mining,
paper sludge and waste from a drinking water treatment plant) activated at
600 ∘C for 2 h to elaborate blended cements. Due to their good
behaviour as future eco-efficient additions, this research is a study by
x-ray fluorescence (XRF), x-ray diffraction (XRD) and scanning electron
microscopy (SEM) of their influence on the performances of blended cement
mixtures (binary and ternary one), with substitutions of pozzolan ratio at
28 days of hydration. The porosity of pozzolanic cements decreases because of the
formation of hydrated phases during pozzolanic reaction. |
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ISSN: | 1680-7359 1680-7340 1680-7359 |
DOI: | 10.5194/adgeo-45-133-2018 |