CHARACTERIZATION AND POTENTIAL USE OF DINGUI CLAY MATERIAL AS PARTIAL SUBSTITUTE FOR CLINKER IN THE MANUFACTURE OF CONSTRUCTION CEMENT

This study investigates the potential of raw clay from Dingui as a partial substitute for clinker, aiming to mitigate the environmental impact of Portland cement production in the Republic of the Congo. A multi-scale characterization was conducted on the raw material, including laser particle size analysis, Atterberg limits, X-ray fluorescence (XRF), and X-ray diffraction (XRD). Thermal activation (calcination) was optimized to transform the kaolinitic phase into reactive metakaolin. Binary blended cements were formulated by partial clinker substitution and evaluated according to EN 197-1 and NCGO 0004-1 2017-09 standards.Analytical results identify the Dingui sample as a highly plastic silty clay (Plasticity Index = 42), predominantly composed of kaolinite and quartz (56% clay, 43% silt). Mechanical tests demonstrate that the formulated binders exhibit significant pozzolanic activity, achieving performance levels comparable to CEM II class cements. The incorporation of calcined clay facilitates a denser micro-architectural matrix through the formation of additional calcium silicate hydrates (C-S-H).In summary, the thermal activation of Dingui clay at 750C reduced the firing energy by almost half compared to clinker (1450C), while also eliminating CO2 emissions from decarbonation. Consequently, this substitute reduces the carbon footprint compared to CEM I cement, thus validating the potential of this local resource for the production of sustainable, low-environmental-impact cements.