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.
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Marxist Arrow by Twin Musicom is licensed under a Creative Commons Attribution License
Source: https://www.youtube.com/watch?v=rBlLC8TUXP0
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Source: https://www.youtube.com/watch?v=U6fBPdu8w9U
This video was sponsored by Skillshare.