Truth be told, today’s “portland cement” is inferior in several ways to many ancient cements, some used by the romans, others by the Egyptians.
Some of the ways portland cement is inferior: shorter life, excessive heat of hydration leading to cracking and the need to control the same, slow development of ultimate strength, low resistance to deterioration under high heat (like in fires), energy intensive mnufacturing, and inferior dimensional stability.
Yet, most folks assume that today’s technology is automatically superior. In the case of portland cement, the reason it is used almost exclusively in lieu of other, much better cements is simple: building codes.
A professor at UWM (Milwaukee) published a study about 20 years ago on how to improve the longevity of our roads — add fly ash to them. Fly ash is the residue from burning coal and is cheap and redily available.
Problem?
Our road builders (who run this state) do not WANT to make the roads last longer. Repaving every 5 years provides employment that would be lost if our roads lasted 30 years.