StructuralQ We are currently working on a tunnel that will cross through a drinking water protection zone in the alluvial aquifer. Do shotcrete technology and materials exist that can be used on groundwater-sensitive areas?
Shotcrete is the same as concrete when evaluated as a material and its exposure to potable water. In the U.S., many admixtures and cements for concrete have been tested and certified to meet the NSF 61 standards for materials exposed to potable water. In my experience, potable water stored in concrete tanks with direct exposure to the concrete (no coatings) has not exhibited any significant rise in alkalinity. Exposure of a tunnel in a groundwater aquifer would seem to have much less contact area per volume of water contained in the aquifer, such that any rise in alkalinity would be miniscule. Because concrete in the U.S. is universally accepted for the storage and transport of potable water, I’d assume that the use of shotcrete in your tunnel would be perfectly acceptable.
