Influence of Theed on strength development and hydration of blended cementitious systems containing titanium slag

A blended cementitious material consisting of cement and titanium slag in a mass ratio of 1:1 was prepared and the influence of varying dosages of tetrakis (2-hydroxyethyl) ethylenediamine (Theed) on the strength development and hydration process of the blended systems was investigated. The hydration process, pore structure and microstructure at different ages were characterised by isothermal conduction calorimetry, X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry and scanning electron microscopy. The results showed that: the addition of Theed (0·01–0·10%) tended to improve the flexural and compressive strength of the blended mortars; the addition of Theed increased the hydration degree of the blended cement pastes before 28 d while delaying the early (before 6 h) hydration, as indicated by isothermal calorimetry measurement; the pore structure of the blended cement pastes after curing for 28 d was modified by Theed, which is beneficial for strength development; the pozzolanic reaction of the titanium slag was enhanced by the presence of Theed, as confirmed by the portlandite content, pore structure measurements and morphological observation.