Pre-tensioned VS Post-tensioned concrete

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    David Kaplan

    Shuai,

    Post-tensioned concrete cannot be made off-site - at least, I would be shocked to find out otherwise.  The reason this is, is because of the process of how it's done.  In a typical installation, all of the concrete forms are installed and all of the rebar and tendons are laid in place.  They then pour the concrete.  Once poured and after it's cured to a certain level, then they use a post-tensioning machine to pull on the tendons to give it the design strength.  This is typically done on a grand scale - as in, the entire ramp of a parking deck, or a large floor slab of a hotel.  You can't transport these types of items from a facility, no truck can hold an entire floor of concrete.  Again, if someone on here can tell me how it could be made off site, I'm happy to listen.  I've done several post-tensioned jobs here in my office and it's totally an on-site process.

    Pre-tensioned concrete is sort of the opposite.  They pull the tendons first to the design strength and then pour the concrete.  I could possibly see this done off-site somewhere but it'd have to be small sections. Again, you're limited to what a truck can transport. 

    I can't answer your question as to why post-tensioned concrete though is higher strength than pre-tensioned.  I'd say google that, I bet you can find the answer pretty quickly.  Hope this helps some!

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    Shuai Cao

    Hi David

     

    Thanks for the input on that.

    I googled the topic and couldn't find a straight answer regarding whether post tensioned has higher strength than pre-tensioned. But I do find out that post-tensioned could be used in bigger scale of construciton like the whole deck of parking garage whichi is similar with what you have mentioned. So I guess the bigger scale of structure capacity is one advantage of post-tenstioned against pre-tensioned.

    I also attached one very helpful link regarding the difference between these two types of construction here for everyone who needs it:

    http://precast.org/wp-content/uploads/2018/03/CP3-Post-tensioning-vs.-Prestressing-Miroslav-Vejvoda_FINAL.pdf

    Thanks again.

     

    Shuai

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