Potential concrete disaster please help

george2016

I was trying to create a dry mix bedding mortar for my metal garden edging tiles

I mixed 6 to 1 ratio sand and cement. Added no water. Mixed it in a wheelbarrow and placed it in a trench I had dug before laying edging into it

Now 24 hours later and mixture does not seem to be setting

Is the situation salvageable? This is hugely disappointing as I laid around 500kg

uck51js9zml2yt

Why would you think it didn't need water?

Just asking, don't know the answer:)

george2016

Priscilla Acidic Flapjack wrote: »

Why would you think it didn't need water?

Just asking, don't know the answer:)

Read that a semi dry mix doesn’t need extra water, using only the water in the sand

Le shovelle

george2016 wrote: »

Read that a semi dry mix doesn’t need extra water, using only the water in the sand

Was the sand damp? I think it will eventually harden in a few days.

Still waters

There probably wouldnt be enough water in the sand in this weather, youll need to add water to make it set, has it made any attempt at setting or is it still dusty

Also, 6 to 1 ratio will take 2 or 3 days to go fully hard

george2016

Still waters wrote: »

There probably wouldnt be enough water in the sand in this weather, youll need to add water to make it set, has it made any attempt at setting or is it still dusty

Also, 6 to 1 ratio will take 2 or 3 days to go fully hard

It was still quite loose and brittle to the touch. I gave it a spray of the garden hose and walked on it to compact it.

Hoping for miracles tomorrow

listermint

I would have done a 4 to 1 myself.

And dry mix doesn't mean dry mix. You have to add water the mix should cling together in a clump if compressed in your hand but shouldn't show and surface water when squeezed but should hold its shape.

Lumen

http://www.pavingexpert.com/layflag3.htm#six2one

A word of caution: this 'slump' can be problematic in hot, dry conditions. If we are having one of our rare 'heatwaves' the natural moisture in the aggregate can be driven off before it gets a chance to hydrate the cement content and you end up with a dry, friable, unset bedding mix. So: if it's hot and dry, use a moist mix rather than semi-dry.

george2016

listermint wrote: »

I would have done a 4 to 1 myself.

And dry mix doesn't mean dry mix. You have to add water the mix should cling together in a clump if compressed in your hand but shouldn't show and surface water when squeezed but should hold its shape.

Thanks

I guess my key question is can the mix now be set in situ by adding water?

Roger Mellie Man on the Telly

Yes of course.

my3cents

george2016 wrote: »

Thanks

I guess my key question is can the mix now be set in situ by adding water?

Firstly it doesn't matter if it takes months to set. I've used a dry mix a lot with garden features. Eventually they set solid.

If you want to add water at this stage just get a watering can with a very fine rose on the end and water the exposed edge like you are watering seedlings. All you need is enough to dampen the surface.

Edit> Even if you do nothing even in dry weather there is enough moisture in the soil the trick is to make sure all the dry mix is covered in soil. Areas just left exposed to the sun may dry out too much as suggested above, if covered that can't really happen. I used to garden on sand (Bagshot sand in the UK a well know soil type in the area) and even there with perfect drainage a dry mix would always go off eventually. Really the only reason you are adding the cement is to stop the sand from getting mixed in the soil. The compacted sand on its own should have enough strength to hold the edging tiles in place.

I wouldn't really expect the mix to start to set for at least a week and even then it won't seem very strong but in a month it should be solid.

10-10-20

Already quoted, but PavingExpert is king here.
If you add water now the mix will likely compact as the sand moves, plus you'll wash the cement away and weaken the mix. So I'd recommend that you spray it lightly, but also spray the surrounding area too so that it entraps moisture and that moisture will slowly wick into the bedding mix. Keep repeating this every 6hrs.
I'm laying bricks for a pond at the moment and I have to moisten the bricks and the surrounding environment to get the mortar to go off right.

The chan chan man

6 to 1 with no water is basically just sand. Its approx 85% sand. As noted, i would give it a light mist spray but wouldn’t hold my breath on it going off either.

george2016

Thanks for all the helpful comments. I will water lightly for the next few days and hopefully I will see some hardening.

I need to do more of this in due course so would people recommend a ratio of 4:1 rather than 6:1 for that?

I want it to hold Apollo metal lawn edging tiles down so that they can’t be removed by mischievous toddlers

my3cents

george2016 wrote: »

Thanks for all the helpful comments. I will water lightly for the next few days and hopefully I will see some hardening.

I need to do more of this in due course so would people recommend a ratio of 4:1 rather than 6:1 for that?

I want it to hold Apollo metal lawn edging tiles down so that they can’t be removed by mischievous toddlers

Don't worry about it the Apollo edging tiles are designed to go into the soil so putting them into a compacted dry mix is going to be fine.

Yes 4:1 is better but I bet that 6:1 goes off hard enough for the job in hand, we aren't making foundations for a house its edging tiles which you may decide to move later anyway.

All the cement is going to do is stop the sand moving away from the tiles into the surrounding soil its not there to support and spread the weight of something heavy like a wall. The tiles themselves will spread the weight over the sandy foundation so I don't see the problem.

coffeyt

Didn't want to open a new thread as similar topic and looking for advice.
I'm planning to lay some sleepers as an edging against a inclined bank of earth with a view to putting in some ground cover plants on the bank.
They don't need to act as a retaining structure as the bank is there about 40 yrs so can't see it moving anytime soon.
Ideally I'd like to have as much as the sleeper visible as possible so hoping to only go down a few inches and fix them in a cement bed.

Can anyone advise on the best cement mix for the job?

Lumen

Are you making a series of single sleeper steps, or putting several on top of each other?

Calahonda52

IFF a single row on edge, I would drill vertical holes in the sleepers and drive some rebar down about 60cms into the soil.
This will keep them from falling over

my3cents

coffeyt wrote: »

Didn't want to open a new thread as similar topic and looking for advice.
I'm planning to lay some sleepers as an edging against a inclined bank of earth with a view to putting in some ground cover plants on the bank.
They don't need to act as a retaining structure as the bank is there about 40 yrs so can't see it moving anytime soon.
Ideally I'd like to have as much as the sleeper visible as possible so hoping to only go down a few inches and fix them in a cement bed.

Can anyone advise on the best cement mix for the job?

You can hold up sleepers with rebar. On edge, bed into the ground on sand for an easy level that will drain then hammer rebar through holes in the front into the soil behind then hammer over the ends of the rebar. You can also cement the rebar into the soil behind the sleepers for extra support. On the wide edge normal way up just use rebar like tent pegs.

In the ground I wouldn't use cement at all instead I'd bed into something with good drainage just think how sleepers are set in railway tracks.

coffeyt

Thanks for all the replies, it'll be a single row of sleepers on the edge.
I never even considered rebar, wouldn't mind but used them 2 years ago when putting in sleepers as steps into back lawn.
This is the front/side lawn, unfortunately all our lawns are raised about 3 ft above ground and front lawn has long bank leading up to it so will look at the rebar option as this would allow me to leave the full sleeper visible.
I have about 18metres of bank to do and they are short sleepers 1.2m long, would 2 rebars be enough per sleeper as that's what I used when doing the steps, these I laid on a thin layer dry mix of sand/cement (mainly sand) to level, so assuming doing the same would work for these?
Or would I be better off just using sand?

Lumen

I've used gravel under low retaining wall of oak sleepers on flat and they're so heavy they're going nowhere, but they are stacked 3 high.

If you want a neater solution than rebar you could drill holes in the sleepers and hammer (or screw) in threaded rod.

my3cents

coffeyt wrote: »

Thanks for all the replies, it'll be a single row of sleepers on the edge.
I never even considered rebar, wouldn't mind but used them 2 years ago when putting in sleepers as steps into back lawn.
This is the front/side lawn, unfortunately all our lawns are raised about 3 ft above ground and front lawn has long bank leading up to it so will look at the rebar option as this would allow me to leave the full sleeper visible.
I have about 18metres of bank to do and they are short sleepers 1.2m long, would 2 rebars be enough per sleeper as that's what I used when doing the steps, these I laid on a thin layer dry mix of sand/cement (mainly sand) to level, so assuming doing the same would work for these?
Or would I be better off just using sand?

Depends how you are using the rebar. No reason you can't secure it to the rear of the sleepers on edge with really large staples. Then you can add as much rebar as you like and no one will see it plus no drilling. Galvanised banding could also be used to secure rebar to the back of the sleepers. Then there are the galvanised roofing straps which might be of some use short, could be used in used in many different ways. Short end screwed to back of sleeper and the other end attached to something deep in the bank that won't move, another chunk of wood or concrete.

Examples from Amazon just because they are easy to find, local hardware/builders merchants will have the same stuff.