The rapid evaporation of surface moisture from concrete can cause map cracking and plastic shrinkage, where cracks can penetrate to the full depth of a concrete slab. This may occur in hot and windy conditions or in low humidity conditions, such as inside heated buildings during cold weather.

According to the American Concrete Institute (ACI), plastic shrinkage cracking of concrete is likely to occur whenever the evaporation rate is more than 1 kg per square metre per hour. The ACI notes that this rate of evaporation can be caused by many combinations of air temperature, relative humidity, concrete temperature and wind velocity.

CHRYSO highlights that plastic shrinkage and the resultant cracking on fresh concrete, can be prevented with the use of its ProFilm 19 product, without the addition of extra water to the concrete mix.

As an evaporation reducer, CHRYSO ProFilm 19 prevents cracking by protecting fresh concrete from the effects of excessive moisture loss in rapid drying conditions and is formulated to achieve this result without increasing the bleed. By spraying this evaporation-reducing product onto fresh concrete surfaces, the user creates a continuous mono-molecular film over the concrete, which inhibits the rapid loss of bleed water.

The company explains that the film lasts as long as the concrete remains plastic, even where floating and trowelling operations must be conducted to create the required surface finish. The effectiveness of the mono-molecular film means that there is no need for water spraying on the surface of the concrete in order to slow the evaporation process.

The water-based product is compliant with guidelines on volatile organic compounds and can be used on a range of horizontal concrete pours where the evaporation rate may exceed the bleeding rate of concrete. Applications include industrial floors, roads, bridge decks, slabs, patios, driveways and sidewalks.