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.