Thermal Treatment and Pozzolanic Activity of Calcined Clay and Shale.

EDGARDO FABIÁN IRASSAR; ALEJANDRA TIRONI; VIVIANA BONAVETTI; MÓNICA ADRIANA TREZZA; CASTELLANO, CLAUDIA CRISTINA; VIVIANA FÁTIMA RAHHAL; HORACIO ARIEL DONZA; ALBERTO NESTOR SCIAN

ACI MATERIALS JOURNAL

AMER CONCRETE INST

Lugar: Detroit; Año: 2019 vol. 116 p. 133 - 143

0889-325X

Clayminerals are the most abundant raw materials for calcined pozzolans. Thermaltransformation includes dehydration, dehy­droxylation, mineral collapse, andneo-formation. Depending on the type and amount of clay mineral, and the natureand amount of associated minerals, the thermal treatment determines the pozzo­lanicactivity. In this paper, 10 natural shales or clays (six illite, two kaolin,and two loess) from Buenos Aires Province (Argentina) were identified usingX-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), andthermogravimetry (TG). The thermal transformation was checked by XRD or FTIRand the elec­trical conductivity (EC) at the calcination window. The pozzolanicactivity was evaluated using the Frattini test and strength activity index(SAI). The Frattini test gives positive results after 7 days and SAI is greaterthan 0.90 at 28 days, but the compressive strength development depends on mainclay mineral. The EC was effec­tive to evaluate the Ca(OH)2 fixationduring the first time and it is related to the specific surface obtained.