Blended cement with illitic calcined clay and calcareous material

IRASSAR, EDGARDO FABIÁN; BONAVETTI, VIVIANA L.; CASTELLANO, CLAUDIA CRISTINA

Prague

Congreso; 15th International Congress on the Chemistry of Cement; 2019

The illitic clays are included in the group of major constituents of the earth´s crust. They can beactivated thermally at 950 °C having pozzolanic properties and contributing to the later strength of the blended cements. On the other hand, the use of finely ground calcareous materials (limestone filler) accelerates the initial hydration of Portland clinker phases causing an increase in strength at early ages. Consequently, the synergistic effect caused by the incorporation of both additions to Portland cement can provide blended cements with an acceptable development of strength and porosity. This paper analyses the incorporation to Portland cement of calcareous material (up to 20%) and/or illitic calcined clay (up to 35%) on the blended cement performance. To study the system, a Composite Central Design was used to obtain the surface responses of the compressive strength; the volume of permeable pores and the non-evaporable water content at 2, 7, 28 and 91 days. Results indicate that at early ages there is a significant increase in hydration rate as the content of calcareous material in ternary blended cements increases. At later ages, the highest strength was obtained with high content of calcined illitic clay and a lower content of calcareous material. The nonevaporable water results indicated that CC acts mainly as diluent of cement at early age, while the LF take this role at later ages.