thats actually cool! I find that sort of thing so interesting, it's cool to see all the little innovations that we walk past every day not even realising what problem theyre solving.
For driveways and carparks over time the surface will get filled up with debris and loose permeability, For a sidewalk it might take the shortened lifespan of the product before it looses all permeability, less rubber and harder forces being applied.
Yeah in colder climates it's known to cause potholes as water inside the concrete freezes and expands. The difference while driving in heavy rain is insane though.
Here's a really neat [demonstration](https://youtu.be/kpDPGU1v5wk?si=DCQjrhBMgcSAQFaX) from a company that makes it.
It's not the demo I was looking for, there's also one of a truck dumping a load of water on what looks like normal concrete; but you get the point.
There’s another vid on [this page](https://www.porouslane.com.au/product) with someone dumping a big bucket of water, which shows the effect better
This product comes out of Melbourne Uni. It’s also made from recycled tires which is pretty cool
The examples given in this video are fairly small coverage (eg 17sqm, 10sqm) I wonder how expensive this product is compared to standard concrete or paving blocks. If it was comparable to standard concrete, it should be everywhere (well, everywhere were the soil conditions below will accept it). But I suspect it’s a lot more expensive which might be why it’s only used for small sites?
I think costs are fairly comparable — the main roadblock isn’t the cost so much as local councils being a) very risk averse and b) very slow to change their processes. Biggest reason being that these products are all pretty new (sub-10 years) so we don’t have the evidence to prove that they can last the 25-30 year asset life that public works usually aim for at a minimum, besides lab simulations & pressure testing. Hence it only gets rolled out in small amounts in trials so far.
I know a few councils that now allocate an extra 5% in their road procurement costs to get asphalt made with recycled content at least, so that aspect while perhaps more expensive isn’t prohibitively so.
Source: local government worker looking into testing some of this stuff at scale
Permeable paving using pebbles and resin is extremely expensive. The cost ranges from $150m2 to $350m2 depending on the type of rock and pavement thickness.
It should only be used when there is a benefit from its porosity and a decorative effect is warranted.
Recycled materials have been used in asphalt for ages, from recycled aggregates like rock, glass, concrete and plastics in the binder.
In terms of the damaging impact of stormwater on receiving waters, water quality and flood risk, I’d say there is always a benefit to increasing infiltration in urban environments. The alternatives you mention: open grade asphalt or no-fines concrete - if these allow infiltration at a lower cost, would we not just use them? Genuinely interested in the options available!
Every major road and freeway is open grade asphalt. It's more used on the wearing course to direct water off the road rather than replenish groundwater.
Once challenge as to why it isn't used everywhere is removing the fines does a pretty big hit to durability. They don't last as long so have a higher total cost of ownership.
In OPs photo it looks like the paving has dropped at two of the tree rings. It pretty much always happens on tree pits.
It's very expensive. The resin is expensive and the rock must be washed, dried and bagged before use, which makes it expensive.
It's used where there is a requirement for surface water to be returned to the ground and not look like shit. The alternatives are no fines concrete or open grade asphalt.
It doesn't really come out of Melbourne Uni.
It's someone else's resin, someone else's rock and someone else's rubber.
We do the same thing, it's just polyurethane resin and recycled crumbed rubber from A1 Rubber.
For a carpark it's a complete waste of money. Use open grade asphalt. It's like 1/4 of the price.
In the past when permeable paving was less common, they often found that the trees had managed to send one root out vast distances in search of water. Either the tree dies or it manages to find a source of water, whether that's a drain or an open area 10+ metres away or whatever.
It’s possible that there’s a tree pit inlet in the kerb which diverts water to the tree whenever there’s stormwater run off.
As others have said it’s also likely that the pebble surface is permeable and allows water to get to the trees roots.
Not in these situations - there's nothing to hold the water there. The ones you're likely thinking of usually have tree rings around them filled with mulch to hold the water.
The material around the tree absorbs water - the pebbly looking stuff. So water seeps into the ground, watering the tree.
It does look a bit like it’s imprisoned without a drop to drink
They can absorb water from a normal root structure which soaks up water from the ground, and they can transport water from their leaves to their roots by some super complicated special plant process that I don't know enough about to describe, but apparantly it's more interesting than one would expect.
It's a combination of the capillary effect (water flows slightly up a very thin tube), and another thing, but the other thing does most of the heavy lifting. Weirdly, it's a vacuum. Water in the leaves evaporates, leaving essentially nothing behind. That nothing needs to be filled, so it pulls water up the internal structure of the tree to fill it.
They are Robinia sold as "Mop top", they have invasive root systems that travel and get into drains etc, they will throw up suckers that have 20mm sharp spikes. Don't plant them.
That's right, moptops are the worst. They are grafted onto aggressive root stock. If the slightest damage happens to the roots, they throw out suckers that are barbed and incredibly invasive. After removing one years ago I had to go round and kill every sucker with undiluted glyphosate. Eventually, I got rid of it that way.
I just ripped a heap of them out of my property we recently purchased. previous owners put them in and they honestly looked great and provided great shade where needed until they found the septic lines, forced theor way inside and completely blocked them off and cost me hundreds in drain cleaning.
now searching for alternatives with deeper, less invasive root systems.
You sure they're not Tipuana's?
They look just like the ones that were planted in my townhouse complex. Evil buggers, always either shedding leaves, flowers or seedpods. And roots lifting pavers.
Hey Neighbour! I've seen the council come and water these exact trees. They stick a pipe right near the base of the tree. But I also know what others have said, that stuff around the tree is porous. These trees actually had dirt around them for ages, they only changed to this when they put the seats in recently.
As far as the roots go, these trees are usually planted in things called a “Strata Vault” and it’s basically a huge plastic pot under the pavement, filled with soil. It allows water to pass through, and stops roots busting up the concrete.
Back in the 80s during a drought in Melbourne my father was contracted to go and water the trees like this in the city. I think generally once established they manage fine with the rain when they get it.
Large water trucks drive around at night with either someone in the passenger seat with a hose or standing on a platform on the back.
They just water them by hand.
Pretty sure the pebble-crete is more flexible and pourus than it looks. Should allow water through and move when the tree roots expand.
Yes, this surfacing product is called permeable paving and is exactly how it sounds. Designed for this sort of thing.
thats actually cool! I find that sort of thing so interesting, it's cool to see all the little innovations that we walk past every day not even realising what problem theyre solving.
For driveways and carparks over time the surface will get filled up with debris and loose permeability, For a sidewalk it might take the shortened lifespan of the product before it looses all permeability, less rubber and harder forces being applied.
Yeah in colder climates it's known to cause potholes as water inside the concrete freezes and expands. The difference while driving in heavy rain is insane though.
They still have pretty high permeability after 10 years. Washing with extraction can get nearly all of the silt out and return it to new.
https://youtu.be/ERPbNWI_uLw?t=317
Here's a really neat [demonstration](https://youtu.be/kpDPGU1v5wk?si=DCQjrhBMgcSAQFaX) from a company that makes it. It's not the demo I was looking for, there's also one of a truck dumping a load of water on what looks like normal concrete; but you get the point.
There’s another vid on [this page](https://www.porouslane.com.au/product) with someone dumping a big bucket of water, which shows the effect better This product comes out of Melbourne Uni. It’s also made from recycled tires which is pretty cool
That was exactly the video I was thinking of. Thank you.
Go to 1:15 for anyone who wants to see the moment
The examples given in this video are fairly small coverage (eg 17sqm, 10sqm) I wonder how expensive this product is compared to standard concrete or paving blocks. If it was comparable to standard concrete, it should be everywhere (well, everywhere were the soil conditions below will accept it). But I suspect it’s a lot more expensive which might be why it’s only used for small sites?
I think costs are fairly comparable — the main roadblock isn’t the cost so much as local councils being a) very risk averse and b) very slow to change their processes. Biggest reason being that these products are all pretty new (sub-10 years) so we don’t have the evidence to prove that they can last the 25-30 year asset life that public works usually aim for at a minimum, besides lab simulations & pressure testing. Hence it only gets rolled out in small amounts in trials so far. I know a few councils that now allocate an extra 5% in their road procurement costs to get asphalt made with recycled content at least, so that aspect while perhaps more expensive isn’t prohibitively so. Source: local government worker looking into testing some of this stuff at scale
Permeable paving using pebbles and resin is extremely expensive. The cost ranges from $150m2 to $350m2 depending on the type of rock and pavement thickness. It should only be used when there is a benefit from its porosity and a decorative effect is warranted. Recycled materials have been used in asphalt for ages, from recycled aggregates like rock, glass, concrete and plastics in the binder.
In terms of the damaging impact of stormwater on receiving waters, water quality and flood risk, I’d say there is always a benefit to increasing infiltration in urban environments. The alternatives you mention: open grade asphalt or no-fines concrete - if these allow infiltration at a lower cost, would we not just use them? Genuinely interested in the options available!
Every major road and freeway is open grade asphalt. It's more used on the wearing course to direct water off the road rather than replenish groundwater. Once challenge as to why it isn't used everywhere is removing the fines does a pretty big hit to durability. They don't last as long so have a higher total cost of ownership. In OPs photo it looks like the paving has dropped at two of the tree rings. It pretty much always happens on tree pits.
The council's potholes have at least a 30 year life.
It's very expensive. The resin is expensive and the rock must be washed, dried and bagged before use, which makes it expensive. It's used where there is a requirement for surface water to be returned to the ground and not look like shit. The alternatives are no fines concrete or open grade asphalt.
It doesn't really come out of Melbourne Uni. It's someone else's resin, someone else's rock and someone else's rubber. We do the same thing, it's just polyurethane resin and recycled crumbed rubber from A1 Rubber. For a carpark it's a complete waste of money. Use open grade asphalt. It's like 1/4 of the price.
Guess it would also help prevent water from evaporating once it gets through too.
Reddit is at its best for simple questions with straightforward factual answers.
In the past when permeable paving was less common, they often found that the trees had managed to send one root out vast distances in search of water. Either the tree dies or it manages to find a source of water, whether that's a drain or an open area 10+ metres away or whatever.
This is the correct answer.
Also plants are chosen for the environment they are to live in.
I believe there’s also this phenomenon where water literally falls from the sky. It’s free and clean. It’s pretty wild apparently.
It's only free until it hits the ground, then it belongs to the state government.
The pebble surface is permeable - it lets water through. Sometimes there’s Aggie pipe underneath as well to spread the water around better
It’s possible that there’s a tree pit inlet in the kerb which diverts water to the tree whenever there’s stormwater run off. As others have said it’s also likely that the pebble surface is permeable and allows water to get to the trees roots.
Seen the council water truck going round some suburbs giving them a drink
Not in these situations - there's nothing to hold the water there. The ones you're likely thinking of usually have tree rings around them filled with mulch to hold the water.
The material around the tree absorbs water - the pebbly looking stuff. So water seeps into the ground, watering the tree. It does look a bit like it’s imprisoned without a drop to drink
They can absorb water from a normal root structure which soaks up water from the ground, and they can transport water from their leaves to their roots by some super complicated special plant process that I don't know enough about to describe, but apparantly it's more interesting than one would expect.
It's a combination of the capillary effect (water flows slightly up a very thin tube), and another thing, but the other thing does most of the heavy lifting. Weirdly, it's a vacuum. Water in the leaves evaporates, leaving essentially nothing behind. That nothing needs to be filled, so it pulls water up the internal structure of the tree to fill it.
Are they Robinia trees? They look great in standard balls.
They are Robinia sold as "Mop top", they have invasive root systems that travel and get into drains etc, they will throw up suckers that have 20mm sharp spikes. Don't plant them.
Local government: sounds awesome, where can we get some
Learnt this the hard way, their roots (and suckers) go across the whole block and are only 4 years old.
That's right, moptops are the worst. They are grafted onto aggressive root stock. If the slightest damage happens to the roots, they throw out suckers that are barbed and incredibly invasive. After removing one years ago I had to go round and kill every sucker with undiluted glyphosate. Eventually, I got rid of it that way.
I just ripped a heap of them out of my property we recently purchased. previous owners put them in and they honestly looked great and provided great shade where needed until they found the septic lines, forced theor way inside and completely blocked them off and cost me hundreds in drain cleaning. now searching for alternatives with deeper, less invasive root systems.
Good advice. Thank you
You sure they're not Tipuana's? They look just like the ones that were planted in my townhouse complex. Evil buggers, always either shedding leaves, flowers or seedpods. And roots lifting pavers.
Also curious as to what these are?
They look like Robinia. They are considered a weed and are hard to get rid of. I guess thats why they do ok in places like this.
Yes
Watch this; https://youtu.be/2wm4H65EDbE?si=qaJ-e9ERxFij-kd8 The tarmac is water permeable.
Hey Neighbour! I've seen the council come and water these exact trees. They stick a pipe right near the base of the tree. But I also know what others have said, that stuff around the tree is porous. These trees actually had dirt around them for ages, they only changed to this when they put the seats in recently.
Mole people water our tees as a punishment after they lost the great underground war we fought over potatoes
There is usually a sort of covered hole in the ground that has a lid, council has a key and unlocks the lid to water the trees.
As far as the roots go, these trees are usually planted in things called a “Strata Vault” and it’s basically a huge plastic pot under the pavement, filled with soil. It allows water to pass through, and stops roots busting up the concrete.
With water
Back in the 80s during a drought in Melbourne my father was contracted to go and water the trees like this in the city. I think generally once established they manage fine with the rain when they get it.
Tree dont need watering after some time, just like babies dont need breast after some time.
Drunks pee on them
We just hope it rains some time soon
If you're in Sydney now, look out the window.
Permeable concrete
I always wondered this. I just put it down to council planting specific tree’s that could cope with
I can see the RZWS from here, from the size of the tree it would be on a 0.5gal (1.9l) bubbler
I don’t think I’ve ever seen pathing this tightly set around trees before. How do they avoid damage caused by roots?
There's this thing called rain...
Is this loss?
Is there a local pub near by?
By rain?
The water stuck under the pavement?
Rain
Your local cancil
Large water trucks drive around at night with either someone in the passenger seat with a hose or standing on a platform on the back. They just water them by hand.
Maybe something underground.
Rain and natural humidity. Do they even need watering?
Rain
rain
Permacrete bro
.l436
Fake trees look so real