Planning to mix concrete for the first time and was thinking of renting a tumbler to mix ~22 bags of coarse concrete. There are some steps I'm unsure about.
1. How many liters can you mix in the tumbler before it needs cleaning? I assume it depends on how quick you are between batches, so perhaps it should be stated as how long you can use the tumbler before it needs cleaning.
2. After washing the tumbler, where do you usually dispose of the "residue"?
3. I will be casting a total of 44 separate cylinders to lock together prefab blocks forming a crawl space foundation. So each casting is only exposed to air about 100^2cm. How should I proceed to prevent the concrete from setting too quickly? Do I need to water it afterward, or is it sufficient to cover it with plastic?
1. How many liters can you mix in the tumbler before it needs cleaning? I assume it depends on how quick you are between batches, so perhaps it should be stated as how long you can use the tumbler before it needs cleaning.
2. After washing the tumbler, where do you usually dispose of the "residue"?
3. I will be casting a total of 44 separate cylinders to lock together prefab blocks forming a crawl space foundation. So each casting is only exposed to air about 100^2cm. How should I proceed to prevent the concrete from setting too quickly? Do I need to water it afterward, or is it sufficient to cover it with plastic?
Coarse concrete in a bag rarely sets too quickly, contains too little cement. Just keep it slightly moist. If you're fast, you probably don't need to clean between. Just add new water.
1. I would say it depends a bit on the pace. If it's continuous, meaning when one load is emptied, the next one is filled, you can keep going until you are finished. I recommend being 2-3 people as everything goes so much smoother that way 
2. For cleaning, regular water is usually enough. Have a surface or a tarp to pour it out on. Personally, I use a large tub, like a masonry tub, to empty into. Once it has hardened, just knock it off the tub and take it to the recycling center.
3. It is somewhat weather-dependent. If it's cloudy/raining, you don't need to water.
That's what I can think of, I'm no expert but I have cast a few times
2. For cleaning, regular water is usually enough. Have a surface or a tarp to pour it out on. Personally, I use a large tub, like a masonry tub, to empty into. Once it has hardened, just knock it off the tub and take it to the recycling center.
3. It is somewhat weather-dependent. If it's cloudy/raining, you don't need to water.
That's what I can think of, I'm no expert but I have cast a few times
Tomture61
Self-builder
· Född i Luleå
· 6 343 posts
Tomture61
Self-builder
- Född i Luleå
- 6,343 posts
With so much concrete, it's never wrong to use a respirator, it gets quite dusty when filling the tumbler.
Sometimes the sticky stuff can get on the blades, so throw in a couple of shovels of coarse gravel + water and let it run for a while, and it will soon be clean. Don't forget the outside! If concrete has dried and set, it sticks.
And respiratory protection is still good.
Cement-based products contain a certain amount of six-worthy chromium (see the movie Erin Brockovich) which is never good to inhale. Indeed, something is added to reduce exposure for those who handle it, but better be safe than sorry.
I mean, a filter costs so little.
Cement-based products contain a certain amount of six-worthy chromium (see the movie Erin Brockovich) which is never good to inhale. Indeed, something is added to reduce exposure for those who handle it, but better be safe than sorry.
I mean, a filter costs so little.
Is this model of respiratory protection sufficient?
https://www.bauhaus.se/halvmask-zekler-1302v-ffp2v-10st-fp
https://www.bauhaus.se/halvmask-zekler-1302v-ffp2v-10st-fp
Oh yes, I think FFP1 will do just fine as well
https://en.wikipedia.org/wiki/FFP_mask
https://en.wikipedia.org/wiki/FFP_mask
According to the Swedish Work Environment Authority, only ppf3 is approved.
Preferably, gummitryne is also recommended.
But as with all private activities, you choose for yourself, and if you're only casting for one day, it probably won't matter.
Preferably, gummitryne is also recommended.
But as with all private activities, you choose for yourself, and if you're only casting for one day, it probably won't matter.
Yes, I agree with that. Filters are, of course, always recommended. But if one behaves a bit sensibly—mixes outdoors, stands upwind, holds breath when it's most dusty—you don’t get much dust on or in you. If it's your job to stand and mix concrete every day, a filter is a given.Mikael_L said:
I am very careful with protection when renovating at home. I always have safety glasses, hearing protection, safety shoes, a harness, and a Sundström half-mask that I put on when it's dusty, but if I'm just mixing a little concrete or plaster outdoors, I use my common sense instead of the half-mask.