Abstract:
The application of chemical grouts based on sodium silicate for (temporary) sealing purposes is a well-known technology used successfully many times over in the past. However, the “ conventional” grouts have some serious detrimental environmental effects and are therefore have been deemed inadmissible in many jurisdictions over time. This hampered their application and as a consequence chemical grouting was replace by other technologies like jet grouting and soil mixing. Nevertheless those technologies have their own economic and environmental disadvantages and as a consequence much effort has been invested in developing now mix designs for chemical grouts to eliminate those detrimental environmental effects while maintaining the desired properties of a grout to act as a sealing material. The results of those endeavors is a new generation of chemical grouts for (temporary) sealing of permeable layers in subsoil to form barriers for groundwater e.g. in deep seated sealing slabs. In this paper the author will first explain the criteria used to determine, if a grout is considered to be environmentally friendly and what tests are performed to check performance against those criteria. Then he will show examples of environmentally friendly mix designs and their performance compared to those criteria. This new generation of chemical grouts has triggered a renaissance of chemical grouting for sealing purposes in regions where environmental regulations and laws have prohibited its application for many years. Keywords: Chemical grouting, sodium silicate, sealing, environmental regulations, mix design