<p>This study investigates the influence of calcination techniques and temperatures on the pozzolanic reactivity of excavated spoil and their subsequent performance when blended with cement. The excavated spoil, which is rich in kaolinite and muscovite, was subjected to soak calcination at 800&#xa0;°C and flash calcination at 900&#xa0;°C and 1000&#xa0;°C. The results demonstrated that soak calcination effectively removed kaolinite, yielding the highest calcined kaolinite content and pozzolanic reactivity, as determined by R³ calorimetry test. Conversely, the flash calcination process led to a partial dehydroxylation of kaolinite, attributable to the short residence time within the experimental apparatus. Despite the absence of five-coordinated Al(V) species in the flash-calcined spoils, their reactivity was confirmed through a variety of reactivity tests. In calcined spoil-blended cement pastes, there was insignificant difference in compressive strength at 28 d, attributed to pore refinement via AFm phase formation. Microstructural analyses indicated that the calcined kaolinite content plays a pivotal role in regulating the formation kinetics of the AFm phases.</p>