How to repair a concrete apron?

[IslandTractor]

I need some advice. The concrete apron on our 100 year old barn has cracked due to the weight of my 40hp tractor and presumably because some of the soil beneath it has eroded away over the years. The apron was never designed for more than horses and wagons so the weight of a 6000+lb tractor/tlb has caused a middle section (directly under the right wheel path) to collapse. Photos show the situation. The apron is pretty thick but steeply sloped compared to a modern apron and is almost a foot thick at the place where it cracked. I live on an island and don't have any concrete contractors easily available so I'm trying to figure out how to effect a reasonable repair myself with bagged concrete/quickcrete.

Can I just make up a quickcrete slurry and pour it in until it fills up? If so, what type of quickcrete should I use? Do I need to remove the broken pieces or can I just pour new concrete down the crack and then use some thicker concrete to patch over the depressed part? I'm hesitant to try to remove the whole apron to start from scratch (how does one get concrete to set at this angle anyways???)

Thanks

 

[Charlesaf3]

THoughts.

I'd tend to want to get the broken stuff up, to find out what is happening to the soil underneath. The concrete wouldn't collapse without that, and your fix will collapse again in all likelihood unless you fix it, or do a rebar reinforcement to bridge things.

Quickcrete concrete will work fine to fix. (concrete = mix of cement plus sand plus stones) You'll probably end up needing more bags than you think.

If you pour concrete over existing, you can use a bonding agent to make sure they "stick". In this case if its thick enough I probably wouldn't worry. If its thin, you'll have to use a sand mix or such like - no gravel. I wouldn't do this.

Concrete will hold a surprising slope if mixed dry. Some of the modified stuff (silpro? forget would have to double check) can be carved as it sets.

You should be able to pull it apart with your backhoe.

If you pull it apart, check for rot on the barn. I bet it'll be there. Concrete against wood is highly sub-optimal. Think sill plate fixing...

You could pull it apart and replace it with wood. Might be easier. I'm in the process of building a similar ramp with wood - think wooden dock/bridges. Bet you might have a nearby ferry dock that would be a good example.

 

[firemanpat2910]

I think I would break it apart. Build a form that is twice as long, and not as steep. Put the broken chunks inside form for fillers. Then rebar and fresh concrete. Just dont ask me to estimate how much concrete, LOL I get that part wrong every time

 

[Willl]

Doing it right will require tearing it all out and redoing.

 

[shinnlinger]

If it were me, I would rip it all out and start over or ignore it. Charles is right that something below the concrete has settled or shifted and patches are only going to continue to crack/collect water. Pat is right that you can use the broken concrete in your new pour.

It looks like you would want a more gradual ramp anyways. Now as for your island issue, do you have a truck and can you get it to the island? I have gone to a gravel yard and filled my truck with a sand gravel mix which they had specifically for concrete. You then get a small gas or electric cement mixer and mix it about 7 scoops of sand/gravel mix to one scoop cement and hose in a little water here and there till it looks good. YOur job looks small enough you could mix premix in your tractor bucket, but it will be a workout. YOu will get better at eying when the mix is right so your first few loads might be off, but by the time you get to the top where it matters you should be fine.

If you go the removal route take Charles advice and check the barn and then bring in dirt/gravel/old cement in lifts and compact as best you can. Rent a plate compactor if possible, but I have chained a piece of firewood under the bucket of my excavator and pile driven trenches to compact before. You could do something similar with your FEL.

A six inch or so concrete cap with rebar in place should be fine, so wire the rebar up or use screen and make to ramp forms for either side and excavate down on the front lip six inches as well.

A stiff mix of concrete will hold on that ramp ok and your new one should be less steep. Take a 2x4 and run it down your forms to screed it off and than take a broom to give your ramp texture and traction.

Having said all that would a load of hardpack gravel treat you ok???

 

[IslandTractor]

Thanks guys. I guess this is more than a simple patch job. I may put it off until later this fall or next spring. Sounds like I need to become a bit more educated about how to use rebar and figure out how much concrete I'll need. I'll also rethink the slope/size thing. I suppose I could use this as an excuse to get a cheap 3PT concrete mixer as virtually anything I buy will cost much less than having a concrete truck come out to the island.

I'll definitely check out the wood situation. As you can imagine we do quite a bit of replacing of rotted wood in 120+ year old buildings out here. Trouble with touching anything on this barn is that it was built "island style" which means it was cobbled together with whatever building materials they had lying around. Lots of suboptimal construction techniques like undersized box beams or repurposed wood in critical places. That plus the powder post beetles makes this thing a challenge to maintain. Still, not many people have a barn with a three holer outhouse built in so I'm doing my best to take care of it.

Thanks again.

 

[Egon]

Does it really need replacement or will it be for looks?

A crushed gravel pad with a better approach angle may be the easiest approach.

If you do use Quickcrete consider adding some Portland cement to mix to give better strength.

 

[IslandTractor]

Does it really need replacement or will it be for looks?

Well, every time I roll over it with the tractor now it wobbles and seems to be getting worse so it is not just for looks. I don't know how to build a gravel alternative. If you look at the photos the threshold for the barn is about a foot off the ground.

 

[Egon]

Just lay the gravel in and drive over it.

 

[radioman]

yup - not using concrete and going with gravel is the best way to go. On the plus side, you wouldnt have to deal with the issues underneath. just keep adding and regrading gravel. Plus you would get the added benefit t get a longer ramp. I am guessing that you wishd you had a less steeper ramp. Do you have a local quarry to get crushed rocks from ? If you can, get crusher run as it has small to large rocks and its a excellent way to get a ramp without concrete. Even if you have to ferry it over, a pickup load worth (maybe a ton worth) should do the trick to make a new ramp.

 

[rambler]

Well, every time I roll over it with the tractor now it wobbles and seems to be getting worse so it is not just for looks. I don't know how to build a gravel alternative. If you look at the photos the threshold for the barn is about a foot off the ground.

Perhaps it is just as hard for you to get gravel as it is to get concrete?

Just make a mound of gravel, make it about 5x farther out than this concrete starts, and slope the mound up to the door. Just a ramp of gravel, or a nicely psloped pile of gravel, to drive on.


--->Paul

 

[Deerlope]

Get some treated lumber and build one out of wood. It will last forever and will not crack.

 

[Dargo]

Doing it right will require tearing it all out and redoing.

I'm no concrete contractor, but I've poured well over 1000 yards at my place so far. I agree with the quoted post which I'm sure also is suggesting rebar reinforcement in the new ramp. I find old concrete without rebar to be very easy to tear out.

 

[Treemonkey1000]

Do you have access to metal plating? Just build a metal ramp.

 

[IslandTractor]

The gravel alternative is intriguing. Anyone have a suggestion on an internet how-to piece for that type of project. I imagine there is more to it than just dumping a bunch of gravel and raking it. How does one keep it from losing form over time? Is gravel any better than concrete up against a wooden barn?

I'm still leaning towards a rebuild and extension of the concrete apron for the simple reason that I know the first one lasted a hundred years or so. If I do that I'll clearly use rebar reinforcement as suggested by several of you. However I'll keep an open mind for alternatives. Probably won't get to this for a couple of months anyway.

 

[firemanpat2910]

the ramp that we drive the forklift up and down at my workplace, is concrete ontop of asphalt. after several years of it settling and the forklift compacting the asphalt at the base of ramp. I bought a 1 inch thick 4'x8' of plate steel. The only problem is its slippery when wet, I keep saying I am gonna take it to my shop and weld some traction v 's to it. This may or may not be an option for you. I also have hauled the steel with me to jobsites to facilitate using forklift on customers uneven parking lots. so it might serve other uses for you

 

[Charlesaf3]

A wood ramp would probably last as long if done properly, and probably be easier.

For gravel - forget what its called around here (I think its crusher run generally) ie fines up to 3/4 will pack down like concrete - I'd just dump it down, compact it in flights, and let it find its own angle of repose.

Or depending one what the drive is, put a long dirt ramp in.

Wood would be best for avoiding future rot though, as anything that holds moisture against untreated wood is bad. A lot of steps out there cause trouble for the wood behind them, you want to let that wood dry out.

 

[Ford850]

The gravel alternative is intriguing. Anyone have a suggestion on an internet how-to piece for that type of project. I imagine there is more to it than just dumping a bunch of gravel and raking it. How does one keep it from losing form over time? Is gravel any better than concrete up against a wooden barn?

I'm still leaning towards a rebuild and extension of the concrete apron for the simple reason that I know the first one lasted a hundred years or so. If I do that I'll clearly use rebar reinforcement as suggested by several of you. However I'll keep an open mind for alternatives. Probably won't get to this for a couple of months anyway.

Gravel is the easiest if you have access to it. As the others said, crusher run, 411, 3/4 down to fines, or whatever they call it in your area is what you want. You can add a treated 2x10 on each side as a frame, angled down away from the barn and into the ground, to hold the sides intact. A few stakes on each board will hold them in place. Dump the crushed stone and drive your tractor over it to compact it. Do this layers, about 3" at a time, to get the best compaction. Save some of the gravel to top it off in a few months after it had a chance to settle some too. I have this on both doors to my barn and it stays in place surprisingly well. I topped it off with #8's (small clean 3/8" crushed stone).

 

[IslandTractor]

Thanks. I will look into the "gravel" option further. I can always bring that out to the island myself in small SUV towed trailer sized batches so it might be quite feasible. It also sounds like there is less potential for disaster compared to the concrete.

What do you put up against the barn sill? Could I just put a 2x12 pressure treated plank there or do you let the gravel actually touch the structure?

 

[Charlesaf3]

I'd put the PT up against the sill. Ideally with 1/8 inch spacers or some such to allow a bit of breathing.

I bet you can get by without the wood sides - just have the apron with 3 sides. I've done something similar leading up to the ramp I'm building for my barn - I terminated the ramp driveway side with 8" granite, and built the gravel up to it. Can't see any reason why 4" more would be a problem.

You could even break up the concrete into chunks and re-use it as part of the base of the fill - it'll save some gravel hauling.