According to a survey of the institute for road and railroad construction at the Ruhr University in Bochum among the refuse incineration plants in Germany, about 2,7 million t of raw ash accumulated in the year 1999. The conditioning was performed in 42 plants so that, after conditioning, about 1,5 million t of refuse incineration ash was available for utilization in road and building construction. If we observe these utilization areas, it is evident that road construction was the most significant utilization area with a rate of about 55 %, here in particular the bases with and without binding agents (solidification/hydraulically bound base, antifreeze subbase and gravel base). Almost one third (450000 t) of the just under 1,5 million t of utilized refuse incineration ash was utilized as backfilling material. For the utilization of the refuse incineration ashes in road construction, a comprehensive technical standard has been in existence for many years. The application of refuse incineration ash in building construction is performed mainly as a backfilling material for structural spaces under concrete slabs or as backfilling in other structural spaces. Here, backfillings and fillings are made generally in layer thicknesses of about 30 cm to 2 m (in exceptional cases even over 4 m). In recent years volume changes have occurred in the refuse incineration ash in a serie of cases, causing in particular heavings of the concrete slab with such structural methods. Lack of volume stability of the refuse incineration ash is seen as the reason in most cases. An independent standard for the application of refuse incineration ash as a backfilling material for use in building construction does not exist. As a substitute, the requirements for road construction are frequently adopted, even though they are not adequate in general for this particular case of application. There is still no method available for testing the volume stability of refuse incineration ashes. Within the framework of a research project of the VGB Research Foundation (VGB project number 178) together with the recycling association, it is planned to develop a laboratory method for testing the volume stability of refuse incineration ash for use as a backfilling material. In addition and after finalisation of the examinations, requirements are to be established with reference to an adequate volume stability of refuse incineration ashes in relation to the mode of application. The research project is subdivided into three parts. In the first part, and in addition to a literature study, examinations were carried out on two selected refuse incineration ashes - both in a fresh condition and after a 3-month storage period - with different testing conditions for the detection and recording of the volume stability. From these volume stability examinations, it was possible to derive that the volume stability test method based on a storage of the refuse incineration ashes at high relative air humidity and increased temperature was the most suitable test method for the subsequent examinations. There, 12 refuse incineration ashes from nine different refuse incineration plants were tested for their volume stability. In part 3, further experimental examinations were carried out which were intended to give the developed test method a greater degree of precision or to shorten it, respectively (30 days instead of 120 days) in order to derive a corresponding working instruction with a suitable assessment/evaluation mode. Practical verification of this method is still pending.