Hello! I've embarked on casting a cover for my water reservoir. The hole is rectangular and 1400x700 mm. It should weigh a little, so I thought concrete was more suitable than, for example, tread plate or aluminum.
I have made the mold 70 mm deep, and the cover will have a 30 mm overlap on the sides and have hinges. The cover will weigh about 150 kg, so I have made a reinforcement mesh in two levels to ensure it holds.
But: The reinforcement is only a maximum of 14 mm into the concrete, and I read now that it should be at least 20 mm in. Will this be a problem? And how can I solve it without rethinking everything?
Grateful for all answers!
Best regards, A happy craftsman in the "wrong" genre
I have made the mold 70 mm deep, and the cover will have a 30 mm overlap on the sides and have hinges. The cover will weigh about 150 kg, so I have made a reinforcement mesh in two levels to ensure it holds.
But: The reinforcement is only a maximum of 14 mm into the concrete, and I read now that it should be at least 20 mm in. Will this be a problem? And how can I solve it without rethinking everything?
Grateful for all answers!
Best regards, A happy craftsman in the "wrong" genre
The reinforcement should be in the lower half of the height because that is where the concrete is subjected to tensile stress when the cover is lifted. In the middle, it doesn't serve a purpose unless it's crack reinforcement - so the bottom reinforcement about 25 mm from the bottom of the form should be good.
Because I didn't think of it And because I don't want to risk dropping it down the well since it becomes damn cumbersome.N NoOne2k said:It is enough to place a layer of reinforcement in the middle
Edit: why not make it like a normal well lid with flanges without hinges?
Since I'm "only" an electrician and have no idea about this, I thought I would be a bit more cautious. But I shouldn't have done that?mexitegel said:
Two layers are not wrong in any way, as long as they are not placed too shallow because they then are not protected by the concrete and start to rust, which makes them larger and causes the concrete to crack.
It’s fundamentally quite simple;
Concrete is very good at handling compressive loads but completely worthless at tensile loads; that’s when it cracks. That’s why reinforcement in the center adds nothing to the strength because there are basically zero loads there. However, it works well for a reinforcing mesh whose purpose is to prevent cracking.
With upper and lower reinforcement, you get a manhole cover that can withstand loads in both “directions.”
It’s fundamentally quite simple;
Concrete is very good at handling compressive loads but completely worthless at tensile loads; that’s when it cracks. That’s why reinforcement in the center adds nothing to the strength because there are basically zero loads there. However, it works well for a reinforcing mesh whose purpose is to prevent cracking.
With upper and lower reinforcement, you get a manhole cover that can withstand loads in both “directions.”
Thank you for a great answer. It matches my theory.
I plan to tilt the lid, so I need two layers of reinforcement. Two layers at 25mm will lie almost flush against each other if the lid is 70 thick. Do you think it's possible to galvanize the reinforcement?
I plan to tilt the lid, so I need two layers of reinforcement. Two layers at 25mm will lie almost flush against each other if the lid is 70 thick. Do you think it's possible to galvanize the reinforcement?
I didn't think about it that's how it should be phrased. But it feels like a great alternative. Thanks!V Värmlandsmicke said:
I find it hard to believe that you wouldn't manage with one layer. There are also recommendations about the minimum distance between the layers. If you want to dive deep into it, this publication is good: https://www.begroup.se/fileadmin/us...roschyrer/BE_Armeringshandboken_2017_webb.pdf
The joints in the hinges are already in place. I have drilled dowels into the wood from the side in the shape that I will drill out and plug screw eyes on either side of the "joints". Then bolt through. The problem now is that I need both layers of reinforcement to get it both over and under the screw eyes. Now the lid's height is not enough.S Stolsben said:
Lost 2020. 
As I replied in another post, I want reinforcement both above and below the bolts/screws that will become the hinges. And now that I've made the grid in two rows I DON'T want to redo it.
But good response. Thank you very much!
Yes, I wish no one to fall down thereS Stingray468 said:Lost 2020.
It will hold up fine. We made a well lid 25 years ago with a diameter of about a meter, and as I remember, we placed about 4 straight and criss-crossed reinforcing bars in the middle of the slab (7 cm thick). Still holds up well today. We carved our names and the year in it... maybe it'll last a few hundred years, who knows.V Värmlandsmicke said:Yes, I don't wish anyone to fall down there