There is a big difference in the "base" cement, even modern Pozzolanic cement is more lasting than Portland. Pozzolan has been considered for years an "inferio

There is a big difference in the "base" cement, even modern Pozzolanic cement is more lasting than Portland. Pozzolan has been considered for years an "inferior" cement (IMHO wrongly) because it is much slower in setting/curing. The typical compresssion test for concrete (it depends on countries/standards) is carried on samples of 28 days of age. A concrete made with Portland cement normally is very near, (let's say conventionally 85-90%) to the maximum strength it will ever reach (the maximum is reached usually within months). A concrete made with Pozzolanic cement, tested in the same manner is more likely to be in the 50-60% range, Pozzolan will normally continue to harden (for years), often overtaking the Portland. Additionally there is a "mass effect" particularly if the environment has a high humidity, that makes the samples being "less representative" of the actual concrete mass in the case of Pozzolanic (a "huge" thickness of Pozzolanic cement has generally speaking more compression resistance than what the test sample may prove). Now if you have to build multi-storey buildings or - say -high raise pillars/columns one of the key factors is time, the soon you can remove formworks and scaffolding and go to the next storey or level is essential and a much faster setting Portland cement has been preferred for all the 20th century, before durability was even thought of. Nowadays there is a trend towards "blended" cements, see: https://en.wikipedia.org/wiki/Pozzolan https://en.wikipedia.org/wiki/Pozzolan https://en.wikipedia.org/wiki/Pozzolan#Use https://en.wikipedia.org/wiki/Pozzolan#Use