Foundation Safety by Means of Injection Instead of Complex Underpinning

The Frankfurt-Hoechst Industrial Park is an innovative chemical and pharmaceutical site in the heart of Europe. Thanks to its organic infrastructure the location provides ideal conditions for companies specialized in research and production. It is ideally linked to the world by international transport routes and the direct vicinity of important suppliers, business markets and financial markets make the Industrial Park all the more attractive.
Due to the presently rather crowded circumstances at the Industrial Park it was decided to expand existing parts of buildings by constructing additional deep basements below the base level. In one construction section, room was needed for an additional power unit underneath a production hall.
This expansion procedure was to be implemented by undermining of the existing hall. This is why the sleeve foundations (individual reinforced footings with an opening for holding a clamping support) thus endangered had to be secured against sliding or slipping caused by the expansion procedure.
The products WEBAC_® 2061 (polymermodified alkali silicate) and WEBAC_® 4170 (epoxy resin) had already been used to stabilize wall a reason the premises in the forefront of this procedure. The stability inspection of these areas produced excellent strength values.
As additional tests on a graded grain-size distribution curve of quartz sand also produced excellent results, it was agreed to use WEBAC_® 2061 for this stabilization procedure. WEBAC_® 2061 is a tried and tested, verylow-viscosity, 2-component injection system based on a polymer-modified alkali silicate for filling, solidifying and stabilizing brittle types of soil, non-binding to slightly binding sand, pebble and sand-gravel mixtures. It is therefore especially recommended for increasing the load-bearing capacity of foundation soil but can also be used for stabilizing concrete, masonry and porous natural stone structures. The injection was implemented per foundation in line with the progress of construction. In doing so, up to 2 m long lances were driven into the foundation soil.
In order to fill and stabilize the foundation soil, the injection lances were positioned vertically and fanshaped for reasons of edge stabilization on the one hand and positioned horizontally for the area underneath the foundation on the other hand.
As early as the day after the injection, the construction process could be continued up to the area of the next foundation. This method was much less complex than the alternative of underpinning which would have been very time-consuming and costly due to the risks of structural damage, and the expansion procedure in the Frankfurt-Hoechst Industrial Park could thus be successfully completed much quicker.