Field Application of Limestone-Calcined Clay Cement in India

Abstract

A majority of the commercial cement production in India is based on substitution of clinker by pozzolanic materials in the form of fly ash from thermal power plants or blast furnace slag. The present study investigates the field application of a new type of ternary blend using limestone, calcined clay and clinker with small amount of gypsum. Four different blends were manufactured under pilot scale. Two different calcined china clay was used; one with a high kaolinite content and the other with a very low kaolinite content but high iron oxide phases giving a white and red colour to the respective blends. Two different limestone with varied quality was also used. Various types of alternate building materials were produced with these four blends for roofing, walling and flooring applications. Comparative study was undertaken with Ordinary Portland and Pozzolan Portland cement locally available. It was found that with a 30 % clinker replacement by high kaolinite calcined china clay the building materials show a higher strength compared to those manufactured with normal available cement. Even the low kaolinite content clay show comparative quality with 30 % replacement. No effect on productivity of the various types of building materials were observed. A two storied demonstration building has also been constructed entirely from the new blended cements. It was concluded that it is possible to replace 30 % or even more clinker by calcined clays to produce acceptable quality building materials.