How does concrete bind when it is dried and harden ?

[rQuestionEngineering]

How does concrete bind when it is dried and harden ?
As you can see, the concrete beams are hardened . Some metal is exposed.

 

[LittleInch]

Search for "concrete cold joint".

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Seppe]

Did you try typing in "how does concrete harden" as a Google search or perhaps checking out something like YouTube?

I would recommend exhausting the rudimentary resources that are available to you and putting in a bit of your own research time. You'll be better (and more knowledgeable) for it.

 

[BridgeSmith]

The metal is exposed because there will be a concrete slab poured on top of the beams.

There are many resources readily available on the curing process of concrete. The short version is that when the cement comes in contact with water, it starts 'hydrating' - growing crystals, that grow into and through each other, creating a rigid mass.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[IRstuff]

How does concrete bind when it is dried and harden ?

What do you see in the photo that can unbind? The rebar is anchored in the concrete simply by the mass of the concrete in front of the rebar that is either welded or strapped together. It's not that different than burying your feet in wet sand at the beach. The mass of the sand keeps your feet from easily coming out, and there's some level of adhesiveness that causes the sand to cling to your skin.

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[hokie66]

Perhaps you mean “bond” rather than “bind”. The bonding of concrete cast at separate times is improved by roughness of the first part, in this case the top of the beams. Cleanliness from debris and dirt is also important. As others have mentioned, much of the longitudinal bonding in your case will be achieved by the reinforcement which crosses the joint and is developed on each side.

 

[JLNJ]

Chemistry!