Avoiding Raveling of Pervious Concrete
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- čas přidán 11. 09. 2024
- Raveling, loose rock on the surface, of pervious concrete can be common. This video will help you to identify the causes of raveling in pervious concrete and tips on how to avoid it.
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A very careful misting with water on a first two days of installation could help. It needs to be started almost immediately after putting the concrete and leveling it. But it could also hurt if not done carefully. But getting the good water mix in the first place, and putting it on a chill cloudy day with a lot moisture is probably the best.
I mean by considering the permeability of soil and pervious concrete and the granular aggregate reservoir underneath the pavement and maximum intensity of rain fall in a area where this pervious concrete is to be implemented.
There is an older book 'Porous Pavements' by Bruce K. Ferguson that talked a bit about how to design a permeable system. But apparently he has a newer book 'Stormwater Infiltration', that looks like it might be even more robust. In the near future we will try do an in-depth blog on this important topic. In the meantime, here is a basic, brief overview:
Measure the infiltration rate of the soil by digging a hole approximately 2 feet deep by 9 inches wide. Presoak a couple of times and then add at least 6 inches of water and time how long it takes to infiltrate.
Determine the maximum amount of rainfall to be captured over a specified period of time, e.g., 24 hours.
Find the storage capacity of the permeable system. Slope could play a big role here, so check out our blog on solutions to handle varying amounts of slope:
perviousproducts.com/pervious-concrete-base-material-depth/
Often the angular or crushed drain rock reservoir has a void ratio (water holding capacity) of around 40%, so doublecheck if the rock you are using is the same and then factor accordingly. Without any slope, 6" of rock could then hold 2.4" of water.
One last thing to check for is draining into the permeable system. Make sure to take into account any drainage or water run-off directed into the system.
Add a half gallon of epoxy resin and a half gallon of hardener to every 5 gallons of you pervious concrete. Mix well with a paddle and a large drill. 1:5 ratio of deep pour epoxy and you pervious concrete mixture. You will be pleaently suprised. Use water misted on top and trowel to smooth it. It will lock together with this recipe and last. No more raveling.
Hi, I admire your expertise and experience in this field. With the suggestions you've given, I can say you are very knowledgeable and respectable. I encounter numerous issues with this type of concrete, and I was hoping for your assistance with my research on it. Your kind and considerate response is highly appreciated. I look forward to your positive feedback.
Hello sir , is there any hydrological design process of pervious concrete pavement according to ACI.
I am not aware of ACI having any specifications for hydrologic design of pervious concrete pavement.
@@perviousproducts6648 thank u sir for your valuable time and reply.....it matters a lot to me ,as a student.
Can adding some sugary water slow down the curing and help in better setting the concrete?
There is generally not an advantage to slowing down the curing process for pervious concrete. It appears the main key to successfully curing pervious concrete is maintaining the proper water content throughout the hydration process. So not allowing water to evaporate during its placement and locking the water in right away as soon as finishing is completed for each little section of the pavement.
As a side note, one has to be extremely careful adding sugar to concrete as it doesn't take much to completely kill/ stop the concrete from curing and setting at all. So sugar in concrete has to be dosed extremely carefully to avoid problems.
Dear sir, my pervious concrete ravels a bit. As my surface needs to be completely flat for it's purpose I was wondering what I can do to fix it. How can i make these areas flat again? Some other material? Can i remake an additional layer of let's say 1 - 2cm on top? the area is a square of 250m2. Thanks a lot in advance 🙏
To fix already raveled pervious concrete, one can apply an overlay over it. To do this begin by removing any remaining loose aggregate. Do this when the pavement is dry and aggressively brush and vacuum it (if too much dust and fines is created and this gets wet, it can clog up the pavement). Then wet the surface and brush on a bonding agent consisting of approximately 1 part concrete glue (typically vae or acrylic latex with around 40% solids) 1 part water and 1 part Portland Cement. The consistency of the bonding agent should be thick enough that it doesn't all just run off into the pavement, and not too thick that it plugs it up too much.
Small sections should be brushed at a time and then immediately covered with the new topping. The diameter of the aggregate used for the topping will determine how thin this topping can be. As a general rule of thumb concrete should not be poured thinner than 3 times the diameter of the aggregate. So if you have a 3 mm (1/8") aggregate then you could apply this topping as thin as 1 cm.
Following the guidelines in this video will help to ensure that your new topping is a success. Because of all the additional surface area created by the voids and uneven surface area of pervious concrete, we have found overlays to be very successful even if there was some raveling in the base pervious concrete. The overlay will lock in any remaining compromised aggregate in the base and will provide a durable, solid pavement that should last for decades.
@@perviousproducts6648 Dear sir, MANY MANY thanks for your reply! REALLY!
Country like India were we have dust and dirt problem does this thing couldn't get block after some time does this product of cement and gravel is dust and dirt proof sorry if u didn't understand my question but if u do please answer
Typically when pervious concrete is placed without other pavement draining onto it or dirt eroding on to it, it will not clog. If a lot of debris and dirt is allowed on to the pavement, it is possible that it can clog up. However, because pervious concrete often allows over 600"/ hour (4.2 mm/ second) of water to flow through it, even if it were to become over 95% clogged any rain event will still be readily absorbed by it. It if were to become more clogged than this because of erosion or the pervious concrete is being used as a drain collecting runoff from surrounding pavement, then much of the original permeability can be restored with pressure washing - blasting the pavement with concentrated water to flush out trapped dirt and debris.
hi, question, I do install pervious concrete, we covered plastic about 10 days, but after 10 days, the part of concrete surface start to loose, so do you have any better suggestion to fix that?
thanks.
Once pervious concrete begins to ravel there are only a couple of options to address it. It can be helpful to keep the affected area clean and remove loose rock regularly for the first few months. After a thorough cleaning, application of an acrylic or polyurethane type sealer can help to protect the surface and minimize future raveling.
The other two ways to fix pervious concrete that is raveling are to cut out and completely remove sections and then repour. Or in most cases a very fine pervious concrete, like PerkTop, can be applied 1/2" (12mm) thick over the entire pervious concrete area. This will not only permanently fix the raveled pervious concrete, but will upgrade and provide a really nice, smooth, consistent surface.
How many days or months it can last
When pervious concrete is installed correctly it will last as long as ordinary concrete, several decades!
I was always told never use a bullfloat as it will seal the surface resulting in more closed voids?
With standard, coarser pervious concrete overworking the surface can cause it to seal up. Using a bullfloat or metal trowels can contribute to this. The good news is one can generally see this happening while it is being finished, and can then take steps to mitigate it from continuing. It may be that there are just some overly wet areas that need to be dug out and fresh material put in, and/ or one can wait a bit to let some of the water evaporate off (being very careful not to wait too long of course) before continuing finishing.
When finishing the base pervious concrete before applying our PerkTop topping, we typically add weight to a magnesium bull float. We vary the weight added depending on the conditions, timing and wetness of the pervious concrete to minimize the amount of sealing up that may occur.