Concrete slab on the ground and moisture control : verification of some methods to improve the moisture conditions in the foundation

Abstract: This work deals with different types of repair methods for concrete slab on the ground damaged by moisture. Many of the available methods involve some kind of mechanical ventilation of the foundation. The basic principle for all these systems is the same. By establishing air movement through an air-permeable layer below or above the concrete slab, the flowing air can absorb moisture from surrounding materials. When the air has passed through the layer, it is transported out, and away from, the foundation. Three methods of this type have been examined by extensive field rneasurements in a few buildings. Improved drainage system constitute another type of repair method frequently used for Concrete slabs in the ground with moisture problems originating from the ground. A system of this type was investigated in a building for two years . The joint water levels close to the drain pipes and below the building were measured every four hours. Three transient numerical models are presented in the report. All the models can be used to predict temperatures in different parts of mechanically-ventilated foundations. One of the models can also be used to predict moisture conditions in mechanically ventilated foundations. Superposition and scaling were applied in order to demonstrate a method of determining the temperature-distribution in a ventilated layer on the basis of diagrams and simple manual calculations.