Advancing Green Construction through Synchrotron Analysis of Calcined Clay Concrete

Concrete heavily relies on Portland cement, whose demand has surged, contributing 8% to global CO2 emissions. Integrating waste materials like calcined clay as supplementary cementitious materials offers a sustainable solution, diverting waste from landfills (waste clays from industrial by-products, mine tailing, and construction works). Calcined clay reduces environmental strain, conserves resources, and lowers production costs due to its lower energy requirements. Additionally, it enhances concrete performance, extending product lifespan and reducing the need for frequent replacements, thus conserving resources in the long term. This research project aims to optimize early-age strength in calcined clay concrete by studying reaction kinetics within the initial 72 hours (in 2-hour intervals) and after seven days. Synchrotron X-ray diffraction (XRD) has the ability, which standard laboratory equipment does not, to identify and quantify crystalline phases formed during these periods. These findings will inform mix proportioning and clay-type selection for enhanced early-age strength by elucidating crystalline phase formation. Micro and nano computed tomography (CT) techniques will characterize the pore structure development and distribution of calcined clay concrete and enable correlation of these findings with strength development. Pore sizes reduce with time (at nanoscale, beyond standard CT resolution) as they are filled with hydration products. The use of synchrotron techniques will enable this refinement in the pore structure to be observed. The investigation spans from 1 and 7 days and to later ages (28 , 90, 180 and 360 days), shedding light on how calcined clay influences pore structure and porosity changes, and how the reactant constituents quantified via XRD, affect the refinement of pore structure of concrete. This will be beneficial in forming a relationship between quantified XRD data(phases forming), the pore structure (from micro/nano CT), and the strength of concrete at different ages (to be measured independently in standard lab experiments in accordance with international standards).