Comparative study of limestone calcined clay cement produced with mechanically activated kaolin and calcined kaolin

Limestone calcined clay cement (LC 3 ) is a promising solution for mitigating CO 2 emissions in cement production by substantially replacing clinker with widely available supplementary cementitious materials . While calcination is the conventional method for activating clay, there is a growing interest in mechanical activation . Incorporating mechanically activated kaolin into LC 3 formulation would offer a novel approach to producing this cement. This study aims to assess the impact of replacing calcined clay (CC) with mechanically activated clay (MC) in LC 3 properties and relevant features. Accordingly, LC 3 with MC substitutions ranging from 0 to 100 wt% were formulated. The resulting cements were characterised to evaluate their physicochemical properties , microstructure, strength , and pore distribution. LC 3 incorporating MC exhibited comparable crystalline and amorphous phases to LC 3 containing CC. However, the incorporation of MC accelerated hydration, leading to the earlier formation of carboaluminates and consumption of portlandite , alongside enhanced compressive strength at early curing stages. At 28 days, LC 3 with 100 wt% of MC displayed similar compressive strength (42 MPa) to LC 3 with 100 wt% of CC (40 MPa) with comparable pore distribution and microstructure. These findings validate MC's potential to substitute CC in LC 3 , offering an alternative for activating clay.