Dewatering, waterproofing and drainage - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 237

Chemical analysis of water samples was limited until recently to just the determination
of the concrete aggressiveness according to DIN 4030 [56] and the steel aggressiveness.
In order to determine the sintering potential, the calcite saturation should also be deter-
mined. The determination of the lime solution capacity as part of the tests according to
DIN 4030 [56] is not sufficient and must be supplemented by the determination of the
calcite saturation according to DIN 38 404-10 [60].
Information about the hardness and hydrogen carbonate hardness can supplement the
evaluation of the degree of attack denoted by the lime dissolving capacity (CO 2 ). Soft
water with a hardness of less than 30 mg CaO/l can dissolve calcium hydroxide out of
hardened cement paste.
The information gained in this way can be used by an expert to interpret whether a drain-
age system can be designed according to the standardised procedure given by the relevant
guidelines or whether additional measures need to be provided. The possible types and
potential extent of such measures are described below.
Design of a basic system for low sintering. As has already been explained, samples of
soil and rock obtained as part of a geological and hydrological investigation programme
can only provide probability statements for the areas between the sampling locations.
Varied experience makes clear that unrecognised water properties can have considerable
consequences for the sintering behaviour of a drainage system.
Figure 5-35 Basic system for tunnel drainage.