What's the difference between concrete and cement? Concrete is the most important construction material on earth and foundation of our modern society. At first glance it seems rudimentary, but there is a tremendous amount of complexity involved in every part of designing and placing concrete. This video is meant to be a bare-bones introduction to the topic, with a cool demonstration of concrete strength using a hydraulic press.
This video shows more destructive testing to answer your questions about concrete. Concrete's greatest weakness is its tensile strength, which can be less than 10% of its compressive strength. So, we often reinforce it to create a composite material strong against all types of stress. This video briefly touches on conventional rebar and prestressed/post-tensioned reinforcement.
This video discusses a few modern techniques that help improve design life of concrete, including roller compacted concrete (RCC) and water reducing admixtures (superplasticizers). There are a whole host of differences between modern concrete and that of the western Roman empire that I didn’t have time to go into, including freeze/thaw damage.
