Characteristics of Portland cement with addition of metakaolin obtained by calcinations of domestic kaolin clay

U Institutu za ispitivanje materijala IMS-Beograd razvijena je tehnologija za dobijanje pucolanskog dodatka - metakaolina iz domaće kaolinske gline Vrbica. Verifikacija pucolanskog ponašanja proizvedenog metakaolina izvršena je određivanjem karakteristika portland cementa sa dodatkom 5 - 20 % metakaolina i upoređenjem sa karakteristikama portland cementa. Upoređenjem karakteristika portland cementa (CEM I) i cementa sa dodatkom metakaolina (CEM II) utvrđeno je da se dodatkom metakaolina skraćuje vreme vezivanja (početak i kraj) i postižu niže vrednosti čvrstoća pri pritisku nakon 2 dana. Nezavisno od udela metakaolina, čvrstoća pri pritisku nakon 7 i 28 dana je veća od čvrstoća portland cementa. Utvrđeno je da se pri dodatku 10 i 15 % metakaolina cementu, čvrstoća pri pritisku povećava približno 15 %.The technology for obtaining pozzolanic additive - metakaolin, from domestic kaolin clay Vrbica, is developed in the Institute for testing of materials IMS-Belgrade. Pozzolanic behavior of the produced metakaolin is verified by determining the characteristics of Portland cement made with addition of 5 to 20 % by mass metakaolin. The characteristics of Portland cement made with addition of metakaolin (CEM II) were compared with Portland cement (CEM I), which was used as a control sample. The composite cements have lower setting time (initial and final) as well as compressive strengths after 2 days. Compressive strengths after 7 and 28 days are greater than compressive strengths obtained for the control cement, independently on the metakaolin content. The addition of 10 and 15 % by mass metakaolin increases compressive strengths for approximately 15 %