Why concrete is not watertight.

Concrete consists in the main of cement, gravel/shingle, sand, water and air. During the hardening process, the concrete is dewatered, which results in an interconnected fine-mesh network of small channels and holes - a capillary system. A fully hardened concrete contains some 20% air. The higher the proportion of water that is used in the concrete mix (measured in WCR, water-cement ratio) the more porous and more air the fully hardened concrete has.
Proportion of air > 20% after dewatering.     Capillary system and pores.              Water is absorbed by the capillary system.

Cracking occurs in all concrete but in different degrees and scope. The plastic shrinkage is assumed to be due to two simultaneous transports of water in the concrete mass. Partly dewatering (water transport from the inside of the concrete to the surface) and partly evaporation (water departing from the surface). When the evaporation exceeds the dewatering, the surface dries out and the risk for cracking increases. In some cases, the result is visible to the naked eye and in other cases a microscope is needed. If a fine water mist is sprayed over the concrete surface, the micro cracks usually appear clearly during the drying process.

  Substantial shrinkage cracks.               Micro cracks visible after wetting.         Casting joints, pouring blemish due to poor vibration.

When concrete is exposed to water or other liquids, it is absorbed by the concrete’s capillaries, micro cracks and cracks by means of the capillary action. The narrower the capillaries - the greater the capillary action. The transport takes place both horizontally and vertically, far into the structure.

This is how Innerseal works

Innerseal penetrates deep into the capillaries, micro cracks and pores. A reaction then takes place between salts and minerals to form a very hard calcium silicate hydride. This results in a crystalline structure that stops the transport of water but lets vapours pass through (diffusion). Because the protection is deeply seated, it is substantially more insensitive to external influences such as abrasion and impacts.

  Innerseal crystallises in the capillaries. The crystals stop free water but allow water vapour to pass through.

Below are two physical experiments that demonstrate Innerseal’s ability to penetrate deep into micro cracks. One concrete cube is treated from the top (e.g. floor) and one from underneath (e.g. ceiling). The micro cracks are filled all the way and sealed, approx. 200 mm. The average penetration depth is measured at 30 mm. The tests were conducted in 2013 by CBI (Cement & Betonginstitutet, SE) and the XRF measurement by BAM (Bundesanstalt für Materialforschung und -prüfung, DE).

  Innerseal fills the entire crack approx. 200 mm deep.              The cracks are filled completely despite the application being applied from underneath.