Treatment of rising damp. Evaluation of six chemical products

Six chemical products were tested in laboratory and then tried out in a case-study in practice: they were applied to the 60 cm thick walls of Hemiksem Abbey. A test method was developed in order to evaluate the effectiveness of the products in laboratory, in a relatively short time. In laboratory the most effective products were silicone micro-emulsion, siloxane in hydrocarbon and, under certain circumstances, siliconate. The most effective products in practice were silicone micro-emulsion and siliconate; even those, though, could not spread over the cross-section of the walls, creating a complete banier. Having applied the products, the moisture content of the walls was measured during a period of ca. 30 months. After 30 months the moisture content of all treated walls was stil! too high to consider the treatments to be effective The principal reasons for the failure are: 1. the penetration/spreading of the products from the injection holes was not sufficient; 2. the polymerization reaction did not or not entirely take place. The high content of moisture in the walls at the injection level may have been a negative factor. Only in the case of siliconate and silicone micro-emulsion is there a chance that a second injection can be succesful, where the first attempt was not satisfactory. Siloxane in hydrocarbon, which gave good results in laboratory, was not applied in the case-study in practice, the producer having decided to use siloxane in alcohol. With siloxane in alcohol, though, very liftte was achieved, both in laboratory and in practice. A method of investigation, analysing the absorption behaviour of cores from the treated walls, obtained by drilling, proved to be perfectly suitable for controlling both application and effectiveness of the products. It is clear that products meant for injection can not guarantee to form a complete barvier against the moisture transport: this can be only achieved by means of mechanica! interruption systems. The advantage of the injection systems lies in the more simple, faster and cheaper application. In the case of injection systems, rather than in that of mechanica! interruption ones, taking additional measures to increase the drying rate of the walls is a necessary part of the treatment.