h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

There's more to this concrete business than meets the eye. I've just started a Civil Engineering degree at Aston University, and we're studying concrete in great depth, for the purpose, presumably, of creating our own monstrosities in a few years.
But there's so much you need to know! Put in too much water, or too little, or the wrong type of cement, and your carefully planned structure can become so much rubble. Honestly, if you could see the shelves full of books dealing with concrete in this library alone!
And yet there is nothing under Civil Engineering projects at the University of Life. Give me time to do some research and I might change that, but remember, I'm only a beginner. You could spend a lifetime studying Civ.Eng, and still have only scratched the surface of the subject.
Modern concrete is only about 150 years old - and it is inferior in many ways to the stuff used to build the Parthanon. What did they know that we don't? The only way to answer that question is to keep right on exploring the different ways of using concrete, and see if something comes up.
Speaking of projects (and I was, look back a bit), I'm doing my first essay and it's on Bridges (well, actually it's on paper, it's just about bridges).
The full title is "The historical development of bridges, and the affect on people" or something like that, I don't have the paper here at the moment. I can find plenty about the history of bridge construction, but very little about the social effects. Can anyone help me here?
Thank you, Cadi.