vivianite drip tests

dripping blue vivianite on wet concrete gives unexpected results.

These are on CEM III/B and CEM I mortar – referring to the kind of cement used in the mixture.

Sometimes the word ‘concrete’ is used loosely to describe both mortar and concrete. Mortar is cement + sand + water while concrete is cement + sand + gravel + water.

The cement type used for concrete is based on the intended use of the concrete, such as exposure to high levels of moisture, acid environments (agricultural companies), or subjected to regular use of de-icing agents etc.

In The Netherlands CEM III/B is usually used, except in the winter when CEM I is used due to its quicker setting.

CEM I : Portland cement with a maximum of 5% other materials.

CEM III: Blast furnace/Portland cement mixture in 3 classes: A, B and C; whereby CEM III/A contains the least (40%) and CEM III/C contains the most (90%) slag.

e.g. VVM CEM III/B contains 32% Portland cement clinker and 68% slag cement.

In the rest of the world CEM II is used a lot, but it does not have durability in wetter / marine situations as are common in The Netherlands. Over decades in practice and in abundant laboratory investigations, CEM III/B concrete has demonstrated consider- ably better performance on durability issues compared to CEM I concrete.

Cement is also defined by its strength development of into classes (32.5 / 42.5 / 52.5), this classification takes place based on a pressure test after 28 days, and within each strength class the performance in time determines ‘Normal’ (N) or ‘Rapid’ (R) version.

NB these do give slightly different outcomes in my works!

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