Have you ever wondered why the surface of so many driveways are falling apart? The problems is more and more widespread. I am going to help you understand what variables contribute to a crumbling driveway surface.
This is a picture of a driveway that is just 6 years old! The surface has completely crumbled! Want to know how to avoid this from happening on your new concrete driveway?
Here are some basic facts about ready mixed concrete, that you, as a consumer need to understand. You already know that driveways are expensive to put in, and even more expensive to replace!
Here are some facts that will help you improve your chances to get a better looking, longer lasting, driveway.
Here are the variables that impact the longevity of the surface or your driveway.
1.The “Bag Mix”
The Bag Mix refers to the amount of cement powder or the number of bags mixed in with sand, gravel, and water for each cubic yard of concrete mix. The higher the bag mix, the stronger the concrete mix, which also has a higher strength PSI (pounds per square inch)
Look how the sidewalk seems to have been spared while the approach and driveway on either side has major damage!
Any contractor bonded to do cement work for Cities are require to use “city mix” for all public curb, gutter and sidewalks. It is an engineered 7 bag mix. So there are 7 bags of cement powder included in every cubic yard of concrete mix.
In my experience most flat work guys out there use a 5 to 6 bag mix for exterior flat work. In my opinion, this is the single biggest factor that allows the surface of driveways to pops and pits so often. I personally would never use anything under a 6 bag mix for a driveway, and I recommend a 6 1/2 or 7 bag bag mix for all driveways where harsh winter conditions exist.
If Cities recognized the value in using a higher quality concrete mix, you should too! The cost is minimal (a few hundred dollars for the whole driveway) while the strength of the surface is better with more cement powder in the mix.
Make sure to specify the bag mix you want used for your exterior flat work!! Otherwise you are leaving the decision up to the guy doing the work, and you guessed it, they will likely use the cheaper bag mix that will not hold up!
Make sure you also tell them you would like a copy of the dispatch tickets that the truck driver leaves on the job site. This ticket tells you everything you need to know about the concrete used. How many yards were delivered, the bag mix ordered, the slump (wetness) as well as, if any water was added to the mix on the job site. This is the only way to verify you got what you specified and paid for.
Most important do not let them tell you, that a 6 1/2 or 7 bag mix is more than necessary or that it will cost you a lot more. You dont have to look far to find the surface of a driveway pitting and falling apart! Flat work guys need to be told how you would like the work done. Otherwise your driveway will never have a chance against cold, harsh climates and salt from the roadways!
This picture shows a extremely rough hand troweled finish. It was either finished too soon after it was poured, or water may have been added to the surface.
2. Flat work crews finish method.
Some workers simply have not been trained properly and do not understand that over working or adding water to the surface dilutes and weakens the cement content in the top layer. Remember it is the cement powder that chemically bonds the concrete mix together.
I see guys throwing water on the surface trying to buy more time, which also dilutes the cement content in the top surface, which once again will almost always lead to the surface falling apart once exposed to harsh winter conditions. Warm climates are more forgiving than harsh ones.
3. Harsh winter conditions.
If you pay attention around town you will notice that you will see more pitting problems on driveway approaches more than anywhere else. This is because the approach gets more salt ground into the surface than anywhere else. Once salt penetrates the surface of the concrete, it begins to break it down.
You may also notice the pitting damage is most concentrated under where you park your vehicles in the driveway. Once again the salty snow and ice from the road is melting or falling off your vehicle and being ground into the surface by the tires.
The number of freeze thaw cycles on your driveway also has a negative impact. For this reason you will see that more North facing driveways end up with surface pitting and problems. The water absorbs into the concretes surface and then freezes breaking up the top surface.
When shoveling or removing ice from concrete be careful! A small chip can grow and multiply quickly. Never chip ice off your driveway with a pointed shovel or pick. That is the most sure way to create a mess all on your own. Teach your teenagers about this. I always see them making this critical mistake!
4. Rough Finished Surface.
Once again this is my opinion based on my own observations over the years. I have been paying attention to all the different variables, in an attempt to understand what things have led to the widespread problems with concrete driveway pitting.
I have noticed that 25 years ago it was protocol to hand finish or “sweat finish” all flat work. Its referred to as sweat finish because it is a lot of hard work that makes you sweat. I grew up putting a fairly smooth, hand troweled finish, on all of our flat work. We never would broom finish anything! Today, you would be really hard pressed to find a crew that hand finishes anything smooth.
We never had problems with pitting in our concrete driveways. Although I believe this is the least important variable, I do believe it can contribute. A rough surface is more porous than a smooth surface. This allows more water to penetrate it and in harsh winter conditions can accelerated the breakdown, that ultimately can lead to concrete driveway pitting. A concrete sealer can help. But it can not save a job done poorly with an inferior concrete mix.
Since I already know you will not find anyone to sweat finish your driveway, make sure they know you would like a broomed finish that is as smooth as possible. This can be described as a dry broomed finish. Which basically means they need to wait longer before they drag the broom across it leaving the final finished surface. Crews get in a hurry to be done so they can clean up and go….which you cant blame them. But they should not rush the timing on the final broom finish!
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