Page 138 - ICJ Jan 2023

TECHNICAL PAPER COLLECTOR’S EDITION

The potential for ternary blends of limestone, and limestone unsuitable for clinker production
calcined clay and clinker, which we call LC 3 can be used. For example, high dolomite contents
(limestone calcined clay cement), to give good produce periclase during clinker production, which
performance at 50% clinker content or less has causes expansion. Such materials can be used
been demonstrated in the collaborative research safely in interground materials, leading to more
between the Laboratory of Construction Materials efficient use of limestone quarries. Depending on
(LMC) at EPFL, Switzerland, and CIDEM in Cuba [10]. the exact scenario, the amount of cement that can
be produced from the same identified limestone
reserve could be increase by up to a factor of two.
3
The kaolinite content needed for LC blends is much
lower than for the “pure” kaolinitic clays used in the 3
ceramic or paper industries. This means that the Further important advantages of LC technology
use of such “low grade” clays would not compete are:
with demand for resources by other industries. Our
experience in India [11] has shown that abundant • Cheaper or similar production costs
amounts of low-grade clays exist as over or under 3
burden in existing quarries, currently regarded as • LC can be produced using the existing
waste. The use of such resources would not require equipment in a cement plant
opening new quarries nor deplete agricultural • Use of LC also does not need any major
3
soils. With an optimum at around 700 to 800°C, the changes in concrete technology.
calcination temperature is much lower than the
1450°C needed for clinker manufacturing, hence This leads to an enormous potential for rapid
consuming less fuel. Furthermore, this calcination uptake of the technology with significant potential
process does not emit chemical CO and can be for CO reduction and efficient use of resources.
2
2
carried out with existing equipment (rotary kilns or
tower calcination units).
3
LC has the potential to provide a large-scale
solution to the two main challenges facing the
Limestone is always available at cement plants. The production of building materials today. A rough
3
LC blends typically contain around 15% limestone,
3
estimation of the impact of LC on the CO
2

The Indian Concrete Journal | November 2018 139