Effects Of K-Struvite On Hydration Behavior Of Magnesium Potassium Phosphate Cement

Increasing the amount of final hydration products of magnesium potassium phosphate cements (MKPC) can improve its mechanical properties and increase its application diversity. This work investigates the influence of the MgKPO4 center dot 6H(2)O (K-struvite) on the hydration behavior and mechanisms of MKPC with Mg/P ratio of 6 at w/c ratio of 0.3. The results indicate the number of exothermic peaks decreases with addition of K-struvite, besides, the hydration heat of MKPC increases first and then decreases compared with MKPC without K-struvite. At w/c ratio of 0.3, traces of K-struvite and Mg(OH)(2) are present in the final hydrated products. The compressive strength of MKPC at 3 d and 28d is 22.5% and 26.1% higher than that of control sample, the porosity of MKPC pastes decreases by 23.5% and 25.3% compared with control sample with 10 wt% of K-struvite at the age of 3d and 28d. K-struvite provides the nucleation site, which increase the quantity of hydration products as nucleating seeding. This work gives an innovative idea to partially replace MKPC by K-struvite, which provide theoretical reference for the practical application of MKPC. (C) 2020 Elsevier Ltd. All rights reserved.