Concrete mixes conforming to CSA A23 can be considered suitable for the exposure conditions. Unfortunately AFAIK the Canadian standards do not define a service life, so you may want to engage a concrete specialist to demonstrate to the client that the mix is suitable. In general I would say the following applies:
- higher cement replacement increases durability of the concrete against chlorides, typically this is the limiting deterioration mechanism for concrete in Canada thanks to deicing salts.
- the initial pH of high SCM mixes is reduced compared to OPC, so resistance to carbonation can be somewhat reduced.
- air entrainment is required for freeze / thaw resistance in cold climates (e.g., Toronto), the admixture dosing may need to be adjusted for high SCM.
- hydration rate and thus strength gain is generally delayed by use of SCMs, hence for thermal crack control we will normally use a higher SCM mix, however ultimate strength gain of the mix will be designed to meet the characteristic strength. I don’t believe there are any issues with long term strength of high SCM mixes, but would be very interested to hear about this.
- resistance to cement paste attack is improved by slag.
For references I would start with CSA A23, ACI 201, and ACI 222. As always speak to your concrete supplier as early as possible to talk through the requirements of the mix and what options are available!
As a final point the ultimate cement replacement mixes are alkali activated materials / geopolymers, and although the mix design is a little trickier, their long term strength and durability are proven in the field since at least the 1950s.