Sulfate and alkali-silica performance of blended cements containing illitic calcined clays

ROSSETTI, AGUSTIN; FALCONE, DARIO; CORDOBA, GISELA; IRASSAR, E.F.

RILEM Bookseries

Springer Netherlands

Año: 2018 vol. 16 p. 117 - 123

2211-0844

Studies of illitic calcined clays are less developed than that corresponding to kaolinitic clays, but illite is one of the more abundant clayed minerals of the earth?s crust, as occurs in the Center of the Buenos Aires Province (Argentina) where the largest cement factories are located. Illite clays develop pozzolanic properties when they are thermally treated at 950, °C, causing dehydroxilation and collapse of structure to form a metastable or amorphous aluminosilicate. Illitic calcined clays don?t present a significant water demand and the compressive strength of blended cements attains to the corresponding to portland cement at 90 days. It is characterized as slow pozzolana. Illite incorporates certain proportion of reactive alumina and high proportion of alkalis, modifying the pore structure. From durability point of view, the incorporation of illite can affect the sulfate resistance of portland cements or the alkali-silica reaction (ASR). The aim of this paper is to study the behavior of two different illite calcined clay blended cements against chemical attack, like sulfate attack and harmful alkali silica reaction, using the test based on the ASTM C 1012 and ASTM C 441, respectively. For sulfate performance, illite calcined clays was blended with a low C3A in 20% and 40% of weight replacement and a very high C3A cement (white), using a 30% of weight replacement; while a low (Na2Oeq,