Fluid transport in Ordinary Portland cement and slag cement from in-situ positron emission tomography

Fluid transport in cementitious matrices and materials is fundamental for many engineering and environmental applications. However, observing and measuring transport processes inside opaque porous solids, such as cement, is technically challenging. We tested the feasibility of using Positron Emission Tomography (PET) for in-situ tracking of fluid being spontaneously imbibed into cementitious matrices. We found that the ¹²⁴I radiotracer enables tracking of the 3D spatiotemporal distribution of the fluids moving through the solid phase. Our measurements show a similar transport rate for Ordinary Portland (CEM І) and slag (CEM ІІІ/B) cement pastes. For both cement types, we found that the fluid penetration depth is proportional to t^0.25. Such a relationship indicates anomalous transport and agrees with standard imbibition/sorptivity experiments. This result confirms that the method offers a reliable technique to explore transport phenomena in cementitious materials.