Reactivity and Microstructure of Calcined Marl as Supplementary Cementitious Material
The reactivity and microstructure of cement paste and mortar where cement is replaced by up to 65 vol.% calcined marl are discussed. It was found that the compressive strength evolution of mortar is following the same linear relation with amount of hydrate water at early ages for different cement replacements (35-65 vol.%), but that this deviates and give higher strength than predicted by the bound water at higher ages. Strength increases on a long term in spite of depleted calcium hydroxide at earlier ages and are discussed in terms of changes in CSH and CAH. XRD does not reveal any unusual crystalline products, but ettringite and hemi-/mono-carboaluminate hydrate. SEM with WDS in a 2 year old mortar found pure CAH in a pore with atomic Ca/Al = 1.6 and some Si that might be a hydrogarnet.
KeywordsCompressive Strength Calcium Hydroxide Hydrate Water Pozzolanic Reaction Light Weight Aggregate
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The paper is based on the work performed in COIN, see www.coinweb.no for information.
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