ABSTRACT
There is evidence after several years of research and practice that materials and procedures having potential to improve the situation do really exist. But it must be emphasized that there is no standard solution suited for every situation. In most cases, improvements are the result of a combination of different functional layers into what is called “an overlay system”. Successful solutions need a good expertise of each case and positive results can only be obtained if the right product is laid in the right way at the right place in the system and in the field.
