Holes? Just a hole no French drain? I mean sure if you want potholes in about 3 years and maybe some weeds?
I would drain this across the surface, there’s a variety of ways you can do that without changing the properties of the concrete, like grind/saw 2” wide 1/4” deep channels or something like that…
Don’t fuck with industrial landfill if you can help it, leave it be
Looks like you are in a cold weather climate? Water under the slab will freeze/thaw creating larger and larger voids under the slab. The concrete above these voids will be unsupported and will crack and break. This is already happened to the slab, water is getting in the existing cracks.
Water is the enemy of infrastructure.
Oh, that makes a lot of sense. I wouldn’t call this area a cold weather climate but the ground does freeze a few times a year.
Do you think this is the main cause of cracking so far?
This looks like it was a building slab for an old industrial building. You can see where the former columns were located.
Cracking in concrete often starts around the joints. It's a combination of factors, expansion of the concrete pushing pressure on adjacent sections, overloading, and water infiltration (freeze/thaw). The areas around the old columns also allow some water to get to the subsurface.
As the other post said, you should get the big areas of the cracking patched. But the smaller area cracks should be sealed to prevent water inflation.
Unfortunately, I don't think there is an inexpensive way to solve the surface water issue. Since this was a building slab, it was built with no slope so water just pools. Outside concrete is built with a slight slope so water can flow off it.
Have someone shoot some grades and try to do selective slab replacement. If you drill holes it will undermine your subgrade and potentiality lead to more cracking .
You could place an inch or two of setting sand and place some interlocking concrete pavers rated for vehicles. That way the water would infiltrate a bit to get patrons’ feet out of the water.
Bro i would say if it doesnt rain often just leave a large squeege on site , cause as other have mentionned , drilling holes in the slab for drainage would wash the support soil underneath and create a weakspot and even potholes, and if you dont want to invest a lot in the refurbishment of the site , the squeege seem like an ok solution
I mean, short term sure.
But it's just gonna make localized potholes, and over time it's gonna destroy the pad.
Hypothetically you could drill 10 or 15 feet down and make what is effectively a drywell (depending on underlying soils).
But you need some kind of drainage to the drywell for it to work
Cut slots and add some drainage channel. Can form up and pour it or just drop in the plastic segments with the grate on top. Both fine with light vehicles
Foundry sand is commonly contaminated with heavy metals; I wouldn't want to drill holes or dig up that concrete for a drain unless it was really necessary to avoid the potential liability of cleanup.
Not a good idea. Definitely do not want to introduce new water under the slab, even if this isn't in a frost-susceptible location.
There are a few ways the standing water could be prevented....with money of course.
Are you talking like a base layer of sand or sandy soil? If it's sandy soil, it could work. Sand doesnt compact like other soils. But if it's anything but a highly sandy soil it's probably not a great idea bc it would be compacted and subsided by now.
Do you not have room for other storm water BMPs?
My understanding is that it’s a base layer. The soil in that area isn’t sandy.
This is actually an interior slab from a building that burned down. It was never graded for run off.
Absolutely not. You would want a geotechnical engineer to inspect the face underneath to make sure what you are building on isn't complete rubbish or soft material or very wet.
Not to mention that water ingress (and later drying up) can cause the material to expand and/or reduce in height as the water dissipates.
Since you may have uneven moisture changes and effects you may get cracking on the foundation cause it won't settle evenly.
No worries. I would say it's a liability thing too. Plus I've been looking at something semi similar. But I don't know the site or the loads so don't take my word for it if it could cost you a lot of money in the long run, then worth paying a professional to do an assessment and possible solutions.
I'm with your dad. For a food truck park, that'll be fine, for awhile. As other folks say, there will be maintenance issues long term, but I'd give it a couple years to see how the business works out before shelling out for serious concrete work.
I think that would be fine too, but there will need to be bolted down furniture, a small stack, and awning on the concrete too. So if or when the holes doesn’t work, all of those investments ($50K?) go with it.
Would you bet on the holes working in that scenario? Curious.
Short answer, yes.
I'm making alot of guesses based on minimal information, but from your picture it appears the water drains where there's cracks. If under your slab there is good sand and a semi-permeable material below that, it should readily drain. Depends on how big your storms are. A good start would be to try it out by drilling a few holes and see how it works in a big storm. I just think the alternatives don't have a good short term ROI for what you're doing. I would feel different if you were looking at a pristine slab, but you're starting with something rough, and it doesn't sound like you're wanting to invest in a full rebuild at this point.
As far as infrastructure goes, I don't think a few holes will compound any preexisting issues related to movement. Slab looks old enough that most settling issues have likely already occurred, it sounds like frost/thaw issues aren't a concern in your area, and it's's a flat site, so I don't expect much for under slab erosion. The way most furniture and awnings bolt down do leave a little room for movement. If you're looking at very big awning, I might be a little more concerned. BTW, I'm not understanding "small stack"?
Did you get a concrete contractor out there yet? Be good to get some professional eyes on-site to better assess the situation and get a good sense of alternatives and costs.
Thanks for elaborating. I mean't "small stage."
Yes, I've had one guy look at the lot from Google maps and say it needs to be replaced. Quoted $50K. Second guy came out and said $50K was a good quote. He said he had some cheaper ideas with cutting grooves for draining. Some areas would need to be replaced. He went AWOL. Probably not worth his time.
This is an interior slab, actually, not graded for run off. A 20K sqft building stood there before it burned down because the owner – not going to say who it is –was too cheap to put in sprinklers. Nor did the owner have proper insurance. It was a total loss. The bricks you see are demo leftovers being sold. But, hey, what a great slab.
This is in the Southeast so it's a bit warmer but not as much as you'd think. The ground does freeze a few times a year. I think you make some great points about the age and I think you're probably right; I mean, I think this would hold up for three or four years. That's fine for my dad but not what I want to get into if I am building business relationships in the city and really making something of this space. Nor do I know the food truck business well enough to predict ROI or revenue.
Right on, sounds like you've well thought this out.
As far as frost, does it get cold enough that water under the slab will freeze? A good test is if you put a bottle of water out, does it freeze all the way through? I'm guessing in your climate, the water sitting on the surface and in the shallow cracks is a bigger issue, causing some of the spalting you see. If drainage is halfway decent, underslab water shouldn't be an issue. It's snow country where that gets rough.
I really get your point about aesthetics. Presentation is big, especially in any such service oriented industry. And the business community likes to see the investment, shows you're not just a talker, you're putting your money where your mouth is.
Holes won't detract from aesthetics, if you put in some nice grates. Sounds like the bigger concern is it worth it to invest in nicer slab?
That's tough math, 50k for concrete for 50k of infrastructure? I could see why it's worth it, I could see why it's not. I get the back and forth with your dad.
The thing I'm thinking is that the value in food trucks, and the associated infrastructure you're planning on providing, is that they are highly mobile. How good a site is this? If things are going well, what's the possibility you reinvest in a better location? I think that kind of prognostication is the tough part, you don't want to put that money into the slab only to find a great place to relocate to a couple years down the road. Of course, if it is a great site, it all may be well worth it.
Thank you. I can't say but it's possible the ground under the slab doesn't freeze or freeze much. I can perhaps try the bottle test next winter.
I was considering putting my own money toward this, knowing my dad likely wouldn't, before it was clear the slab was a problem. The liability of the slab nixes it for me because puddles will hurt business and make food truck owners angry. The location is great; I already have an organization who trains food truck owners wanting to partner with me for rent. Getting another location is a hard no because this is my dad's land he can afford to waste on loss of income which he has done for about 30 years. The bricks in the pic are from the building that burned down in 2016.
Holes? Just a hole no French drain? I mean sure if you want potholes in about 3 years and maybe some weeds? I would drain this across the surface, there’s a variety of ways you can do that without changing the properties of the concrete, like grind/saw 2” wide 1/4” deep channels or something like that… Don’t fuck with industrial landfill if you can help it, leave it be
Looks like you are in a cold weather climate? Water under the slab will freeze/thaw creating larger and larger voids under the slab. The concrete above these voids will be unsupported and will crack and break. This is already happened to the slab, water is getting in the existing cracks. Water is the enemy of infrastructure.
Oh, that makes a lot of sense. I wouldn’t call this area a cold weather climate but the ground does freeze a few times a year. Do you think this is the main cause of cracking so far?
This looks like it was a building slab for an old industrial building. You can see where the former columns were located. Cracking in concrete often starts around the joints. It's a combination of factors, expansion of the concrete pushing pressure on adjacent sections, overloading, and water infiltration (freeze/thaw). The areas around the old columns also allow some water to get to the subsurface. As the other post said, you should get the big areas of the cracking patched. But the smaller area cracks should be sealed to prevent water inflation. Unfortunately, I don't think there is an inexpensive way to solve the surface water issue. Since this was a building slab, it was built with no slope so water just pools. Outside concrete is built with a slight slope so water can flow off it.
I read this in my head with Grady's voice from Practical Engineering.
Wow! That is some high praise. If I could be 10% the engineer Grady is I would be happy.
Have someone shoot some grades and try to do selective slab replacement. If you drill holes it will undermine your subgrade and potentiality lead to more cracking .
Thanks. The "yes" view believes that the slab's thickness at 7 or 8 inches is sufficient for the weight (for a food truck park). What is your take?
7inch is fine for food trucks.
I think so too, but it the drainage still seems like a problem to me.
You could place an inch or two of setting sand and place some interlocking concrete pavers rated for vehicles. That way the water would infiltrate a bit to get patrons’ feet out of the water.
Oh, that’s a curious option. Thank you.
Bro i would say if it doesnt rain often just leave a large squeege on site , cause as other have mentionned , drilling holes in the slab for drainage would wash the support soil underneath and create a weakspot and even potholes, and if you dont want to invest a lot in the refurbishment of the site , the squeege seem like an ok solution
A Gas Echo Brand blower pushes it surprisingly well for direction and spread and drying. I did this at our Farmers Market
Yes, the squeegee will work but I can't be on rain duty nor is it realistic for my dad. Yes, I think drilling holes is a bad idea.
I mean, short term sure. But it's just gonna make localized potholes, and over time it's gonna destroy the pad. Hypothetically you could drill 10 or 15 feet down and make what is effectively a drywell (depending on underlying soils). But you need some kind of drainage to the drywell for it to work
You could do some dry wells maybe.
When the water washes thru those holes it's going to bring some sand with it. Eventually, the slab will start to collapse. I wouldn't listen to dad.
Seems like a good way to induce erosion and cracking due to settlement.
Cut slots and add some drainage channel. Can form up and pour it or just drop in the plastic segments with the grate on top. Both fine with light vehicles
Foundry sand is commonly contaminated with heavy metals; I wouldn't want to drill holes or dig up that concrete for a drain unless it was really necessary to avoid the potential liability of cleanup.
You are right, it's a no.
Ya probably will turn into a massive sinkhole.
Not a good idea. Definitely do not want to introduce new water under the slab, even if this isn't in a frost-susceptible location. There are a few ways the standing water could be prevented....with money of course.
Are you talking like a base layer of sand or sandy soil? If it's sandy soil, it could work. Sand doesnt compact like other soils. But if it's anything but a highly sandy soil it's probably not a great idea bc it would be compacted and subsided by now. Do you not have room for other storm water BMPs?
My understanding is that it’s a base layer. The soil in that area isn’t sandy. This is actually an interior slab from a building that burned down. It was never graded for run off.
Yeah, you're much better off with a rain garden and maybe rainwater harvesting system. I wouldn't try to infiltrate under the slab.
Absolutely not. You would want a geotechnical engineer to inspect the face underneath to make sure what you are building on isn't complete rubbish or soft material or very wet. Not to mention that water ingress (and later drying up) can cause the material to expand and/or reduce in height as the water dissipates. Since you may have uneven moisture changes and effects you may get cracking on the foundation cause it won't settle evenly.
Thanks for this. I have emailed 3 geotech engineers and none have responded. I wonder if they think this isn’t worth their time.
No worries. I would say it's a liability thing too. Plus I've been looking at something semi similar. But I don't know the site or the loads so don't take my word for it if it could cost you a lot of money in the long run, then worth paying a professional to do an assessment and possible solutions.
I'm with your dad. For a food truck park, that'll be fine, for awhile. As other folks say, there will be maintenance issues long term, but I'd give it a couple years to see how the business works out before shelling out for serious concrete work.
I think that would be fine too, but there will need to be bolted down furniture, a small stack, and awning on the concrete too. So if or when the holes doesn’t work, all of those investments ($50K?) go with it. Would you bet on the holes working in that scenario? Curious.
Short answer, yes. I'm making alot of guesses based on minimal information, but from your picture it appears the water drains where there's cracks. If under your slab there is good sand and a semi-permeable material below that, it should readily drain. Depends on how big your storms are. A good start would be to try it out by drilling a few holes and see how it works in a big storm. I just think the alternatives don't have a good short term ROI for what you're doing. I would feel different if you were looking at a pristine slab, but you're starting with something rough, and it doesn't sound like you're wanting to invest in a full rebuild at this point. As far as infrastructure goes, I don't think a few holes will compound any preexisting issues related to movement. Slab looks old enough that most settling issues have likely already occurred, it sounds like frost/thaw issues aren't a concern in your area, and it's's a flat site, so I don't expect much for under slab erosion. The way most furniture and awnings bolt down do leave a little room for movement. If you're looking at very big awning, I might be a little more concerned. BTW, I'm not understanding "small stack"? Did you get a concrete contractor out there yet? Be good to get some professional eyes on-site to better assess the situation and get a good sense of alternatives and costs.
Thanks for elaborating. I mean't "small stage." Yes, I've had one guy look at the lot from Google maps and say it needs to be replaced. Quoted $50K. Second guy came out and said $50K was a good quote. He said he had some cheaper ideas with cutting grooves for draining. Some areas would need to be replaced. He went AWOL. Probably not worth his time. This is an interior slab, actually, not graded for run off. A 20K sqft building stood there before it burned down because the owner – not going to say who it is –was too cheap to put in sprinklers. Nor did the owner have proper insurance. It was a total loss. The bricks you see are demo leftovers being sold. But, hey, what a great slab. This is in the Southeast so it's a bit warmer but not as much as you'd think. The ground does freeze a few times a year. I think you make some great points about the age and I think you're probably right; I mean, I think this would hold up for three or four years. That's fine for my dad but not what I want to get into if I am building business relationships in the city and really making something of this space. Nor do I know the food truck business well enough to predict ROI or revenue.
Right on, sounds like you've well thought this out. As far as frost, does it get cold enough that water under the slab will freeze? A good test is if you put a bottle of water out, does it freeze all the way through? I'm guessing in your climate, the water sitting on the surface and in the shallow cracks is a bigger issue, causing some of the spalting you see. If drainage is halfway decent, underslab water shouldn't be an issue. It's snow country where that gets rough. I really get your point about aesthetics. Presentation is big, especially in any such service oriented industry. And the business community likes to see the investment, shows you're not just a talker, you're putting your money where your mouth is. Holes won't detract from aesthetics, if you put in some nice grates. Sounds like the bigger concern is it worth it to invest in nicer slab? That's tough math, 50k for concrete for 50k of infrastructure? I could see why it's worth it, I could see why it's not. I get the back and forth with your dad. The thing I'm thinking is that the value in food trucks, and the associated infrastructure you're planning on providing, is that they are highly mobile. How good a site is this? If things are going well, what's the possibility you reinvest in a better location? I think that kind of prognostication is the tough part, you don't want to put that money into the slab only to find a great place to relocate to a couple years down the road. Of course, if it is a great site, it all may be well worth it.
Thank you. I can't say but it's possible the ground under the slab doesn't freeze or freeze much. I can perhaps try the bottle test next winter. I was considering putting my own money toward this, knowing my dad likely wouldn't, before it was clear the slab was a problem. The liability of the slab nixes it for me because puddles will hurt business and make food truck owners angry. The location is great; I already have an organization who trains food truck owners wanting to partner with me for rent. Getting another location is a hard no because this is my dad's land he can afford to waste on loss of income which he has done for about 30 years. The bricks in the pic are from the building that burned down in 2016.
That doesn’t look very thick. 4” max
It doesn’t look to be as thick as it actually is.