How to place a pervious concrete path 

Thank you for the kind feedback!

If you email us through our website, perviousproducts.com, we may be able to facilitate something. Thank you

I am not aware of any school dedicated to pervious concrete training. In the U.S. there is the NRMCA (National Ready Mix Concrete Association). They provide trainings and certifications for placing pervious concrete. However their trainings are pretty basic, typically just half day or so events that do not adequately address the proper mix design, the critical timing considerations around the sun and weather, or even many of the nuances of placing pervious concrete. If you are interested in learning how to place very fine pervious concrete, you would be welcome to come out and follow along for one of our projects sometime!

Pervious concrete has been installed successfully all over the U.S. and Canada for over 40 years. So it does survive some pretty heavy freeze/ thaw cycles. Pervious concrete needs to have the proper air entrainment and/ or other freeze/ thaw resistant attributes just like ordinary concrete. However in regards to the visible water flowing through the pavement getting trapped in it and freezing, this is not typically a problem because it still has room to expand, up and out of the pavement. This is perhaps similar as to why rain gutters with water in them don't typically get damaged during the winter months. That all being said, pervious concrete should be placed over a well-draining, typically crushed rock base. This will minimize the occurrence of water getting trapped in the pavement during a freeze/ thaw cycle as well as provide protection from frost heave as long as the crushed rock base is designed with the proper depth.

Unfortunately our geographic range for pervious concrete installations for now is limited to the west coast. Thank you for asking!

Pervious concrete generally pulls slightly lower compressive strengths than ordinary concrete, typically 2000 psi (14 MPa)to 3000 psi (21 MPa), compared to 2500 (17 MPa) to 4000 psi (28 MPa) for ordinary concrete. However even at the average of 2500 psi, this is over 7 times the necessary strength for firetrucks, so it is more than strong enough. The challenge with concrete primarily is to reduce cracking and since pervious concrete tends to shrink less than ordinary concrete and because it is often poured over a thick layer of gravel, pervious concrete tends to crack much less than ordinary concrete. One of the challenges with pervious concrete can be to create a tight, well-placed surface to reduce raveling and create optimum surface durability. Check our video 'Avoiding Raveling of Pervious Concrete' to see how best to achieve this: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xkkgTXbYvBI.html Also if higher strengths with pervious concrete really are desired, they can be achieved.

Sealing or adding adhesive to raveling, loose rock on the surface of pervious concrete will not do much to slowing this from occurring. However, raveling will typically stop about 6 months after the installation. If around this time the surface is aggressively brushed and vacuumed and/ or blown off, then applying a film-forming, high solids sealer, like an acrylic or polyurethane can help to minimize the typically small amount of further raveling that can still occur over the years. If the raveling is significant and the pavement is not considered acceptable and it needs to be replaced, then applying a 1/2" thick layer of PerkTop over it instead will permanently lock and solidify the surface. PerkTop will also provide a whole new aesthetic and cost much less than having to replace the entire pavement.

It is a coarse silica sand. Even though fine aggregate pervious concrete, less than 1/8" or 1 to 3 mm in size, can be tricky to make mix designs for and work with, we like the final results so much more than the typical coarser 3/8" (9mm) or 1/4" (6mm) aggregate that is often used.

Yes, pervious concrete can be stained a different color. Most concrete stain and sealers are compatible with pervious concrete. We like to use Ecoprocote's 'Soycrete Concrete Stain & Sealer'. They claim it lasts virtually forever, but even still we try to tint the pervious concrete a similar color as the final stain color.

Yes, pervious concrete is very suitable in areas of heavy rainfall. Pervious concrete, when properly installed, should last and wear similar to ordinary concrete for most pedestrian and low-vehicular traffic areas. The wearing of the very top layer of cement will not affect the aggregate below.

Thanks for sharing your out of the box thinking. It is possible that adding a bit of cement or other admix to the spray water could reduce the evaporation rate and/ or improve the quality of the finish. To that extent, some pervious concrete installers will use evaporation retarders, which I believe are mostly alcohol-based, to provide for more time between finishing the pervious concrete and covering with plastic. In this case, these need to be applied carefully because over application can weaken the surface and lead to raveling and over reliance on its anti-evaporation qualities can also still lead to drying out of the the surface and to raveling because it does have a limited effective time.

Even though the mix consistency may seem similar, Pervious Concrete is very different from Wet Mix Macadam. Pervious concrete generally utilizes a gap-graded aggregate, to maximize the void space. Also the binder in pervious concrete is cementitious, typically Portland Cement, and therefore pervious concrete achieves compressive strengths of 2000 psi (14 MPa) to 3000 psi (21 MPa) and higher.

Yes, the cement for pervious concrete can be tinted a wide range of colors. With the use of white portland cement or other lighter colored cements, it can even be made to be white and in very light colors. However, because pervious concrete traditionally needs to be cured with plastic, this will discolor it and produce efflorescence, whitish appearance. Therefore we typically use a stain to produce the final color, which offsets the discoloration.

I have never noticed or heard of any issues with the soil eroding out from under pervious concrete or of it becoming weak and compromising the pavement. Typically pervious concrete is placed over several inches of open drain rock with a filter fabric on bottom, between the subsoil base and the drain rock. The drain rock acts as a reservoir, storing water until it can be absorbed into the soil below. The drain rock along with the fabric also serves to provide additional stability to the pavement and buffers soil movement, like expansion when wet. Now if the soil is sandy or well-draining enough on its own, the pervious concrete can be placed directly on top of it without the added drain rock. In this case getting the sandy soil wet does not weaken it, it can actually make it more cohesive. And because it drains so well, no erosion is likely to occur.

Please see our video, "How To Make Pervious Concrete" for mix design ratio and other info.

Thanks for asking! We are in fact just beginning to make pervious concrete blocks/ pavers. We are currently making them for a specialty application, but hope to one day soon be able to offer them for retail sale as well.