Industrial production of limestone calcined clay cement: experience and insights

Abstract

The reduction of the clinker factor in cement has emerged as the most promising solution to reduce carbon dioxide (CO2) emissions and to improve sustainability. Limestone calcined clay cement (LC3) is a ternary cement where the synergy between calcined clay and limestone allows the reduction of clinker factors to 0·5. In order to understand practical issues in the production of LC3, such as the selection of raw material and production conditions, industrial production of LC3 has been carried out at three locations in India. A wide range of raw materials was collected from various parts of India and characterised to evaluate their suitability for the production of LC3. Both static and rotary calciners were used for the production of calcined clay. Open- and closed-circuit ball mills were used. Limestones with various impurities and compositions were utilised. It has been observed that lower-grade clay and limestone can be used and that the quality control during the production process can be carried out using widely available techniques. Field trials have shown that the cement can be used without any changes to the existing construction methodologies. This paper discusses the key lessons and insights gained from these trial productions.

Sustainability-based decision support framework for choosing concrete mixture proportions

“…The concept of the A-index can be extended to other types of degradation and phenomena that could limit the service life of a structure. [18][19][20]. The fine aggregate used was river sand (5 mm down), and the coarse aggregate was crushed granite in two fractions (of 10 mm down and 20 mm down).…”

Hydration behaviour of limestone-calcined clay and limestone-slag blends in ternary cement

“…The compressive strength of LC 3 was comparable to OPC up to 28 days, whereas the SLSC blend gained a lower strength than OPC and LC 3 . While the initial strength development in LC 3 blend was rapid, the strength gain after 7 days was not significant [8,10,11]. Such behaviour is reported due to the higher rate of hydration at early ages in LC 3 [28].…”

“…The most efficient way of LS utilisation could be in ternary blended cement with a reactive supplementary cementitious material (SCM) that has high alumina content such as kaolinitic calcined clay (CC) or slag (S). It can support the reaction between calcium carbonate and the alumina in the SCM and help in improving the early hydration and strength even at higher clinker replacement levels [8,[10][11][12]. Such ternary blended cements are already standardised in several countries.…”

“…Many studies have tried investigating the mechanical and durability properties of ternary blended cements containing LS and the reactivity properties of blended SCMs containing LS [8, 10-12, 14, 15, 19-21]. The key reason for the interest in ternary blended cements is their having better sustainability credentials in comparison to OPC [10,22]. However, most available studies have only focused on one individual type of ternary cement containing either clay, slag or fly ash with LS [8,10,12,17,19].…”

“…The key reason for the interest in ternary blended cements is their having better sustainability credentials in comparison to OPC [10,22]. However, most available studies have only focused on one individual type of ternary cement containing either clay, slag or fly ash with LS [8,10,12,17,19]. Very limited studies can be found on the comparison of the effect of the SCM type on the efficiency of LS reactivity.…”