I see cracked or broken concrete paths on a regular basis. Sometimes they have been paths that were laid 40 years ago and sometimes they have been as new as 2-3 months old which begs the question, what actually causes concrete to crack and break? With so many broken paths, are they as hard wearing as we are lead to believe? In this article I hope to cover it all!
What causes a concrete path to crack?
If your path is relatively new and it’s already showing signs of cracks or the edges breaking away then I hate to be the bearer of bad news but it’s most likely down to the person that built the concrete path. First of all, you can’t just lay concrete on top of earth. As the earth moves and sinks over time, you will have hollow spots underneath your concrete, also known as weak spots. Imagine walking on concrete that is practically floating in places – It won’t take long for your new path to start cracking or breaking away at the edges.
Making a strong sturdy concrete path is all about the preparation. If I were building a new path then I would typically dig the area to an absolute minimum of 6 inches. I would first lay 2 inches of type 1 MOT (similar to hardcore) before compacting it with a wacker plate. This is the process needed to stop the earth moving beneath the concrete path and therefore giving it a strong sub base. Ballast is the best sand to use when building a concrete path as it contains large stones, making it much less prone to cracking compared to using a fine sand such building sand. 4 inches would be the minimum depth needed to make a strong path.
In theory, if your new concrete path or base is fairly new and already showing signs of cracks then there is a good chance that there is either not enough type 1 MOT used or there is too thin a depth of concrete layed. If however your concrete path is fairly old (10+ years) then there is a good chance it’s down to wear and tear. After all, nothing lasts forever!
I’ve removed concrete paths and bases in the past that were 20-30 years old and despite seeing the type 1 MOT or hardcore beneath, the ground has still managed to move over time and therefore leaving huges gaps underneath the concrete.
What tools do I need to repair my cracked or broken concrete path?
Below are a list of tools needed to repair your cracked concrete path. Luckily there’s not a huge amount of tools needed but the ones that are needed can be fairly expensive. I would expect to pay around the £200 mark which although sounds expensive, still beats the price of paying a professional to do the repairs for you. It might be more cost effective to rent some of the equipment or even purchase second hand if you’re only going to be using them for a one-off job. Below are the list of tools needed to fix your concrete path.
- 9″ angle grinder with masonry cutting disc
- Concrete breaker
- Hand saw
- Trowel set
- Spirit level set
- Cement mixer (optional)
Below is a list of the tools above in product view. If you click on the link then you will be directed to the product on the Amazon store. As an Amazon affiliate partner I receive a commission for any purchase made when using a link from this website.
Use the straight edge on your spirit level to mark your lines on either side of your crack. If you are repairing broken corners of a path then you are going to need to square it off and install new gravel boards before laying new concrete. A spirit level will be needed to make sure the edging boards are level. For simple small cracks, a spirit level may not even be needed at all – But they are always handy to have!
A 9″ angle grinder is what’s needed to cut into the lines on the outside of your crack(s, the start of your channel.
An electric breaker is a must have tool to break through and remove the concrete from within your cut lines. Finally you will have an empty channel where your cracks once were!
For those bigger jobs such as repairing large sections of your concrete path then it might be worth getting a cement mixer to do the mixing for you!
For those smaller jobs, why not forget about a cement mixer and just mix the sand and cement yourself on a mixing tray?
How to fix a cracked or broken concrete path
If you have a crack on your path and are thinking about simply filling it with new concrete then I wouldn’t bother. There will be no strength added to the concrete by doing this and the new concrete wouldn’t take long to come away from the crack. Instead you are going to want to use your spirit level (or any other straight object) to mark a straight line on either side of the crack. I try to draw my line 3 inches of each sude if the crack, making a total marked width of 6 inches. This will be your channel. The wider your channel the stronger your repair will be.
Once you have marked your channel, it’s time to put on your earmuffs and goggles and start cutting as deep as you can into the marked lines with your 9″ grinder.
When you have your cuts made, you’ll want to break the concrete inside your channel by using your breaker. Start from the edge and work your way backwards, through the channel, to avoid damaging the rest of the concrete path or base. Once broken, remove all of the concrete so that you are left with nothing but an empty channel where your crack once was. If your concrete path or base had broken edges instead of a crack then your are going to want to square off the area instead of cutting a trench like channel.
When you are happy, use some 6 inch gravel boards to edge off the ends of the channel so that when you pour your new concrete in later it will have nowhere to escape and finish at the same edge as the rest of your path. All I do is push the gravel boards flush up against the sides of the concrete path, matching the same height and using steaks to secure into place.
Finally it’s time to lay your new concrete where your crack once was. I would recommend using a 5:1 mix (5 part ballast to 1 part cement) and make sure it’s a wet mix. When you’ve filled the channel to the height of the rest of the path, you can simply use a trowel or even spirit level to give it a nice finish to the rest of your concrete path. A wet sponge or brush helps blend your new concrete into your existing path. Leave to set for 2-3 days before walking on your newly repaired path.
My thoughts on how to repair a cracked or broken concrete path
Repairing an old concrete path showing cracks or breaks really isn’t that difficult. If you’re needing to repair a large section then I would recommend reading my article titled ‘how to build a concrete base yourself‘. Any hands on person that carries out DIY tasks should be able to do it with little to no problems. The biggest issue is working out whether it’s more time and cost effective to purchase the tools yourself or have a professional do the work for you. Below is the shortened version on how to repair a cracked concrete path.
- Mark a straight line of either side of the crack, I would recommend 3 inches away frim the crack on each side to give a total width of 6 inches, although not essential.
- Use a 9″ angle grinder with a masonry cutting disc to cut into the line.
- Use an electric breaker to carefully break away the concrete, leaving an empty channel within the concrete.
- Use 6 inch gravel boards (or any other suitable timber) to edge off the edge of the concrete path, stopping your new concrete from escaping and finishing flush with your existing path.
- Mix a wet mix of ballast and cement. For every 5 shovels of ballast, use 1 shovel of cement (5:1).
- Put the morter into your channel and use a trowel to smooth the surface and have it finish flush to the height of your existing path.
- You can use a wet sponge or brush to help blend and smooth your new concrete into your existing path.
- Leave to set! Your repaired concrete path should be ready to walk on in 2-3 days!