Metakaolin in white cement mortars

Here are presented thè results of an experimental study conducted to investigate thè physical- mechanical performance of white cement bound products. White cement is a key ingredient in buildings with unplastered concrete blockwork facades of special architectural value. A metakaolin pozzolan is used instead of thè more commonly used dark grey silica fumé. An acrylic product is used as superplasticizer, testing different concentrations in an effort to reduce thè larger amount of water required by white cement pastes. The physical-mechanical properties of thè examined mortars were found to depend decisively on thè poor performance of thè superplasticizer that proved to be unable to reduce thè water-to-cement ratio significantly. On thè other hand, thè metakaolins tested, especially thè products obtained by thè calcination of Sardinian kaolinic clays, containing thermodynamically unstable silica phases, appeared to be more effective especially at short curing times.