Concrete experts!
A question has arisen regarding how strong a cast concrete beam will be if it has been unintentionally cast in 3 parts, i.e. with 2 casting joints in the concrete. The beam is about 8m long, 40cm in height, and 15cm wide and was originally intended to be cast in one pour.
Now, it was not done that way, but instead, it was cast in 3 separate rounds in 3 roughly equal parts.
Can it be said that the beam has the same load-bearing capacity as if it had been cast at once? If not, can anything be said about how much the load-bearing capacity has decreased?
A question has arisen regarding how strong a cast concrete beam will be if it has been unintentionally cast in 3 parts, i.e. with 2 casting joints in the concrete. The beam is about 8m long, 40cm in height, and 15cm wide and was originally intended to be cast in one pour.
Now, it was not done that way, but instead, it was cast in 3 separate rounds in 3 roughly equal parts.
Can it be said that the beam has the same load-bearing capacity as if it had been cast at once? If not, can anything be said about how much the load-bearing capacity has decreased?
I'm just speculating here, but it feels like a significant reduction in load-bearing capacity to do so. But as I said, I don't know.
Locke?
Locke?
If we think about how a concrete beam works.
The top side compresses: then the casting joint doesn't matter much, that's what concrete is good at
The underside stretches: then the casting joint doesn't matter much since the reinforcement bars take the major load
My guess is that the beam achieves 90% strength compared to casting it in one piece.
Provided there are no air pockets in the joints, which would weaken the top side.
/Odd
The top side compresses: then the casting joint doesn't matter much, that's what concrete is good at
The underside stretches: then the casting joint doesn't matter much since the reinforcement bars take the major load
My guess is that the beam achieves 90% strength compared to casting it in one piece.
Provided there are no air pockets in the joints, which would weaken the top side.
/Odd
Had the concrete had time to cure between batches, or did it just take longer to mix than you intended?
This is usually called cold joints, and it's not good.
Reinforcement in non-prestressed concrete does not take any load until the concrete has cracked. It normally does this across the entire cross-section, thanks in part to crack-distributing reinforcement, often mesh.
When there are local zones where the concrete has been weakened for various reasons, uneven cracking occurs. Normally, concrete cracks in microscopic fractures, but in these cases, visible cracks with exposed reinforcement can occur.
You risk underperformance in terms of strength, undesired deflection, and shortened lifespan. I would not have released such a product.
This is usually called cold joints, and it's not good.
Reinforcement in non-prestressed concrete does not take any load until the concrete has cracked. It normally does this across the entire cross-section, thanks in part to crack-distributing reinforcement, often mesh.
When there are local zones where the concrete has been weakened for various reasons, uneven cracking occurs. Normally, concrete cracks in microscopic fractures, but in these cases, visible cracks with exposed reinforcement can occur.
You risk underperformance in terms of strength, undesired deflection, and shortened lifespan. I would not have released such a product.