ᐅ Concrete slab, insufficient cement content in the concrete mix
Created on: 14 Jun 2020 15:06
E
Eriwan2
Hello, I am quite inexperienced with construction and very worried about the following issue:
I want to build a swimming pool in my garden, measuring 3x5x1.5 meters (10x16x5 feet), using Styrofoam formwork blocks that will be filled with concrete.
A friend who works in construction helped me pour the base slab (20cm (8 inches) thick) over the weekend, and for various reasons, we had to mix the concrete ourselves from cement and gravel.
I read online that the ideal mix ratio is 1 part cement to 4 parts gravel by weight, and this is exactly what my friend had told me before. He mixed the concrete, and I did the pouring.
Now that the slab is finished, I checked the delivery notes. When I calculate everything, we used exactly 8 tons of gravel and 1.25 tons of cement. But for a 1:4 ratio, we should have used 2 tons of cement.
He says this is not a problem and gave me explanations I don’t fully understand. (For example, there was some water in the gravel, so we actually used less gravel than was delivered. The gravel was indeed damp, but as a layperson, I am still very concerned if this will truly hold.
Does anyone have experience with this and could please share some advice?
I want to build a swimming pool in my garden, measuring 3x5x1.5 meters (10x16x5 feet), using Styrofoam formwork blocks that will be filled with concrete.
A friend who works in construction helped me pour the base slab (20cm (8 inches) thick) over the weekend, and for various reasons, we had to mix the concrete ourselves from cement and gravel.
I read online that the ideal mix ratio is 1 part cement to 4 parts gravel by weight, and this is exactly what my friend had told me before. He mixed the concrete, and I did the pouring.
Now that the slab is finished, I checked the delivery notes. When I calculate everything, we used exactly 8 tons of gravel and 1.25 tons of cement. But for a 1:4 ratio, we should have used 2 tons of cement.
He says this is not a problem and gave me explanations I don’t fully understand. (For example, there was some water in the gravel, so we actually used less gravel than was delivered. The gravel was indeed damp, but as a layperson, I am still very concerned if this will truly hold.
Does anyone have experience with this and could please share some advice?
H
HilfeHilfe14 Jun 2020 19:03danixf schrieb:
Is there at least any reinforcement steel inside and was it compacted?
If proper reinforcement steel was installed and the concrete was well compacted, I wouldn’t worry. No, no reinforcement steel. Hollow blocks were filled.
The steel is in place.
There are 2 layers of reinforcing mesh, and on the sides, there are U-shaped bent meshes (which basically connect the top and bottom mesh), and at the corners, there are angle irons made of reinforcing steel.
It’s probably not compacted very much.
Just rolled down the chute with a wheelbarrow and spread out with a shovel.
There are 2 layers of reinforcing mesh, and on the sides, there are U-shaped bent meshes (which basically connect the top and bottom mesh), and at the corners, there are angle irons made of reinforcing steel.
It’s probably not compacted very much.
Just rolled down the chute with a wheelbarrow and spread out with a shovel.
HilfeHilfe schrieb:
No steel. Hollow blocks filled in.I’m talking about the foundation slab, not the blocks. The blocks will still be installed, but I also plan to reinforce them both vertically and horizontally, and there is reinforcement protruding from the foundation slab for connection. So it won’t fail due to lack of steel.H
HilfeHilfe15 Jun 2020 06:31Eriwan2 schrieb:
I’m talking about the concrete slab, not the blocks. The blocks will come later, but I was planning to reinforce them both vertically and horizontally, and there’s also a connecting reinforcement protruding from the slab.
So, it won’t fail due to the rebar. Then it should be fine. You have concrete blocks and you’re adding more concrete.
Otherwise, only a structural engineer can advise you.
Water always exerts pressure.
Joedreck schrieb:
As a complete beginner in concrete, I would be satisfied with that. You could probably build a house on the slab. It will hold those few tons as long as the ground underneath was properly prepared and nothing sinks. Does this mean that YOU are also a beginner, or that you know your stuff?
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