Traditional earthen techniques suffer from low production rates, making them, for the European market, less affordable than conventional methods. To overcome this limitation, the deflocculation/coagulation poured earth process was developed to use infrastructure from the concrete industry, enhancing efficiency. This process employs a deflocculant alongside a low soluble coagulant that counteracts its action on fine particles, thereby controlling the rheological properties of the earth binder over time. This control enables material pouring and unmolding without the need for a hydraulic binder. The method is well understood for pure kaolinite but its application to other earth binder components remains underexplored, particularly the interaction between the deflocculant and the silt fraction. This research investigates how different silt mineralogies interact with a deflocculant that has proven its efficiency in ceramic field: sodium hexametaphosphate. Results indicate that pastes with quartz show interactions similar to kaolinite, while those with limestone are more challenging to model. In limestone pastes, calcite dissolution increases pH and Ca2⁺ concentration, leading to Ca-phosphate complexation instead of hexametaphosphate adsorption. Consequently, the deflocculant dosage must be carefully adjusted according to the earth binder’s mineral composition, underscoring the need for further study.