Shed base with mesh fabric, in sections.

[MRRB]

The saga continues. I have the materials for the formwork. The plan size will be 6m by 5m. I aim to go and pick up some A142 mesh fabric tomorrow, which comes as 4800 x 2400, so I'm hoping that 3 of these will do the job, and it seems reasonable to cast the base over 3 days, since I will likely be on my own.

So the plan is that after the formwork is set up and everything's ready, to support the first piece of mesh (meshmen) and pour concrete, leaving some of the mesh, say 200mm, protuding, to use to join into the middle 1/3 the next day, and deal with the last section likewise next day.

However, it seems there needs to be a temporary retainer to stop the mix from slumping into the unfilled area, and so that the edge of a board can be used to level the first section.

I'm not sure what to do about that. There's the next day's work to worry about too, 'cos the first days will still be green, and levelling the second section won't be easy without ripping the surface of the first, and I won't be able to go on the first section I assume.

Any ideas?

[Tony McC]

Apologies for being late to this - had all sorts of health issues with angina during the heatwave and now an arthritic knee that is driving me mad with pain.


Leaving rebar projecting from a slab to be covered by convcrete at a later date is bad practice. The day joint that wiill inevitably be formed beween the first pour and the subsequent pour could allow water to penetrate and reach the steel.

The preferred method would be to split the slab into 3 bays, ensuring all steel has at least 50mm of cover, and, if absolutely necessary, rely on dowels/tie-bars to link adjacent bays.....

https://www.pavingexpert.com/repair#fulldepthrepair


....dowels could be placed in the preceding pour to save the effort of drilling into green concrete and relying on something like LokSet to hold the dowels in place.

What you've done isn't the end of the world, but, for future reference, it's better to keep steel covered.

[MRRB]

Apologies for being late to this - had all sorts of health issues with angina during the heatwave and now an arthritic knee that is driving me mad with pain.


Leaving rebar projecting from a slab to be covered by convcrete at a later date is bad practice. The day joint that wiill inevitably be formed beween the first pour and the subsequent pour could allow water to penetrate and reach the steel.

The preferred method would be to split the slab into 3 bays, ensuring all steel has at least 50mm of cover, and, if absolutely necessary, rely on dowels/tie-bars to link adjacent bays.....

https://www.pavingexpert.com/repair#fulldepthrepair


....dowels could be placed in the preceding pour to save the effort of drilling into green concrete and relying on something like LokSet to hold the dowels in place.

What you've done isn't the end of the world, but, for future reference, it's better to keep steel covered.

Edit: I am sorry to hear of your health issues, by the way, it was flaming hot for a while, and arthuritis is an abstrad.

But oh bugother. The 4800mm length of the 5050mm mesh at least leaves a little "extra" at the edge of the slab (which I made in three sections), where there isn't any steel, and the building's walls and roof will hopefully stop water getting in (Visqueen under slab). What a mistake-a to make-a!

Do I misunderstand here? The link says "make in sections, ensuring steel is covered min 50mm, then join with (steel?) dowels". Aren't the dowels themselves then subject to oxidisation?

I ended up by screwing 2x2 theough the mesh into 2x1 roof batten on edge to make inter-section forms, bodging with odds and ends to hold the deeper side/edges.

This picture shows the situation:

https://i.ibb.co/n6Dbk9L/IMG-20200826-130329.jpg