Compaction pore

Compaction pores are natural voids in the solid concrete that cannot be removed despite due diligence on the recipe, mixing, placement, and compaction of the fresh concrete. A compaction pore content of about 1 - 2 Vol.-% is considered as reference value without negative impact on the quality of the fresh concrete, e.g. as to duration, waterproofness, etc. Contrary to the natural air voids, i.e. the compaction pores, there are the air voids that are artificially generated with the help of admixtures (air-entraining agents) e.g. for improving the frost resistance.