1H NMR relaxation analysis of cement-based materials: The spin-lock T <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg" display="inline" id="d1e284"> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>1</mml:mn> <mml:mi>ρ</mml:mi> </mm

In recent years, 1 H NMR relaxometry has become a mainstream methodology for study of the nano-porosity of cement-based materials. For the most part, measurements have been carried out using variants of the classic CPMG T 2 and solid-echo NMR pulse sequences and, to a lesser extent, the inversion recovery T 1 sequence. Notwithstanding considerable successes, these methods all have one or another disadvantage, quite often associated with reliable differentiation of the so-called inter-layer and quasi-crystalline water fractions. In this paper, we introduce the application of the T 1 ρ spin-lock experiment as a convenient alternative methodology. Early results are presented. Measuring T 1 ρ overcomes some of the earlier difficulties, potentially has some wider advantages but also has raised some interesting questions of interpretation associated with the partitioning of water between C-S-H interlayer spaces and quasi-crystalline phases. • NMR spin-lock T 1 ρ to measure water fractionation in cement pores is introduced. • Compared to CPMG T 2 , water in inter-layer spaces is partitioned differently. • This offers a route to sub-partitioning structured water/ 1 H in inter-layer spaces.