A single‐sided ¹H NMR study of the self‐drying properties of a ternary self‐levelling underlayment

Self‐leveling underlayments (SLU) are used for smoothing and levelling sub‐floors before any flexible flooring is applied. Though being comparatively simple in its requirements, commercial SLUs have become one of the most complex cementitious mixtures in dry‐mortar technology. By using ternary binders, most SLUs are designed to be self‐drying, binding most of the mixing water in crystalline cementitious phases, allowing a fast work progress. In this study, the simultaneous hydration and drying of a commercial SLU are monitored with single‐sided ¹H nuclear magnetic resonance (NMR). This technique allows the quantification of chemically bound water and water in different pore environments with superior time and depth resolution. The technique is combined with conventional testing techniques enabling a more comprehensive view on the processes at hand. Results allow quantification of hydration and self‐drying, superimposed by physical drying effects over time. Additionally, the drying of a PVC adhesive through water absorption into a well‐dried SLU are visualized with this technique. The results are discussed in the context of moisture transport processes and floor‐laying readiness of the material.