1H T1 NMR relaxation in hydrating cement pastes

Spin-lattice relaxation of exchangeable water protons in hydrating Portland cement clinker pastes is considered in this work. The analysis of T-1 data is performed by spin-grouping technique obtaining the components each characterized by values of T-1 and fraction in total magnetization (M-0). Based on the model of fast exchange between free and bound water molecules within each pore and assuming the discrete pores, the components are associated with particular groups of pores in a paste. The decreasing of components' T-1 during curing time and behaviour of corresponding M-0 values are in accordance with the rising of specific surface area as well as pore system development in a hydrating paste. It is also shown that small amounts of mica additions, after an initial accelerating influence, exhibit a retarding effect on the Portland cement clinker hydration. The gel pores to capillaries percentage fraction ratio is lower in hydrated samples with greater content of added mica, indicating their higher porosity.