Basic properties


Precautions measures/Industry standards

Prompt natural cement is primarily used in mortar (Prompt natural cement mortar or natural lime–Prompt natural cement mortar). It is sometimes used in concrete. It has always been used in the same way as hydraulic binders.

However, given its quick setting (2 minutes at 20°C), a number of precautions need to be taken so as to ensure high quality, long-lasting work.


  • Prepare the worksite before mixing the mortar or concrete.
  • Use clean sand (and granulates).
  • Do not mix Prompt natural cement and sand in advance: the humidity in the sand hydrates the Prompt natural cement and initiates the setting process.
  • Avoid using too much water. This causes reduced strength, shrinkage and cracking. A mortar with very damp sand will need less water.
  • Only prepare the quantity you can use before it starts setting.

Industry standards: 

  • Work on a clean, damp surface (for bonding).
  • Use must be finished before it starts to set. In order to have enough time, use the retardant additive Tempo.
  • The retardant additive Tempo is often useful, even for Prompt natural cement mortars with lime.
  • After it begins to set, do not add water. Do not re-mix. Do not smooth the mortar, because setting will only occur once. (risk of breakage)
  • Close the bag tightly after use.
  • Store upside-down, and away from damp.