Study of the potential use of LC³ as a binder in civil construction: a review

A bibliometric analysis of LC 3 cement was performed in the following databases: Scopus, Science Direct and Web of Science using combinations of words: "LC 3 ", "cement", "Limestone calcined clay", "concrete", "mortar" and "paste". The countries with the highest number of publications were India (48), China (37), United States (26) and Switzerland (22). Brazil published only 5 articles, without any international co-authorship. In the scientific part, it was identified that the optimum calcination temperature of clay is between 600 and 850 °C. Limestone acts as a filler (filling, nucleation and dilution), with the nucleation of hydration products being more prominent, accelerating the alite (C 3 S) reaction, which increases the formation of C-S-H. For low kaolinite content (27%), the optimum clay/limestone ratio would be 2:1, while for clays with high kaolinite content (80%), this ratio should be 1:2.5. In addition to the traditional reactions of Portland cement, three main reactions occur in LC 3 systems: pozzolanic reaction between the silicoaluminate of metakaolin and the CH from the cement hydration, forming C-S-H and C-A-S-H (hydrated calcium aluminosilicate), which contribute to strength and void filling; reaction between the alumina of C 3 A, the CaCO 3 of limestone and CH, forming Mc and Hc, which leaves more sulphates available for the formation of ettringite; and reaction between the aluminates of metakaolin and the CaCO 3 of limestone, forming additional Mc and Hc. As a result, matrices with a lower corrosion rate are obtained in environments at risk of chlorides and sulphates in LC 3 concrete. It is concluded that LC 3 is a good binder from a technical and environmental point of view. It has great potential for use in civil construction, however, further studies are still needed on: effects of curing, adjustments to sulphate content, durability and extreme situations of high temperatures (fire).