When boreholes reach groundwater, its level is recorded and a sample is taken for analysis. Foundations and basements stay in contact with this water for the life of the building, and some of the salts it carries attack concrete and steel slowly and out of sight.
To follow the level after drilling, an observation standpipe may be installed in the borehole and the water level measured in it at intervals with a dip meter, as in the photo, which also shows the measuring tape and a water sample taken for analysis.
What do we measure?
- Chlorides: they penetrate concrete and corrode the reinforcement, which expands and cracks the cover.
- Sulfates: they react with cement compounds and cause expansion and breakdown of the concrete.
- pH: acidic water weakens the cement paste over time.
How are the results used?
Depending on how severe the exposure is, the study may recommend one or more of the following:
- Sulfate-resisting cement or suitable additions.
- A lower water-cement ratio to reduce the permeability of the concrete.
- Thicker concrete cover over the reinforcement.
- Waterproofing of foundations and buried walls with suitable materials.
In coastal and sabkha areas, where groundwater is close to the surface and salt levels are high, these precautions matter even more.
We run these analyses in our laboratory on water and soil samples, as part of a geotechnical study or as standalone tests.