ABSTRACT
Seepage of water through masonry structures is one of the principal causes of their deterioration. It washes out the mortar and, when associated with freeze-thaw cycles, is responsible for spalling and splitting. When the water carries salts (either applied to the road surface for melting ice or picked up as the water percolates through the structure), it may evaporate from the surface leaving behind inorganic crystals which can push the surface off as flakes. The water may be a nuisance when it emerges, by reducing the value of a space under viaducts. It is particularly annoying to pedestrians when it is contaminated with oil and may cause damage to road surfaces. There is therefore considerable advantage in installing waterproofing and drainage.
