Not just in concrete, but also their expansion of the use of prefab terracotta components for homes, aided the sheer scale on which Romanized citizens were able to construct homes, villas, private baths, etc.
I should have had those Romans pour my new driveway.
Cracked in a year.
It really is amazing how constant empirical experimentation led to improvements. The same happened with metallurgy, ceramics, glass, and many other materials.
Interestingly, the Romans added powdered volcanic ash to their concrete mix, which made it very much stronger. This was rediscovered only a few years ago and now modern cement includes this material.
One could say that Roman architectural design vaulted forward, not simply one dome idea after another.
I always wondered what calculating system the Romans used in their construction. Multiplying mmcvii y cciii, etc. must have been a pain.