How best to resurface our sloped driveway?

[heykrazi]

Hi folks. Gained a lot from this forum last month, and need some help again 🙇🏻‍🙏🏼 as my research and discussions with tradespeople is not clarifying things for me. 

We have a sloped driveway on our property. It seems to be roadbase mixed with some sort of local gravel, and has been there for at least 10 years I’d say. Within the last 12 months, with such heavy rains around Sydney, the driveway has degraded, formed channels and washed away in parts. We need it redone ASAP.
To give you an idea of the slope: https://bit.ly/3pgASX2

We can’t afford concrete or pavers.
I’m not keen on asphalt or bitumen because a charcoal/black look just won’t go with our house.

So I feel like I’m left with 3 options:
– stabilized roadbase, which would come up as a medium-grey colour
– stabilized decomposed granite, which I could possibly get in a few colours
– coloured bitumen spray seal using Bushmates (eg. through Illawarra Spray Seal)

I have a landscaper telling me they’ve been getting good results with stabilized decomposed granite, but I’ve read some things online that this can be dusty when dry, muddy when wet, and might just end up washing down the slope after some rains?
I have looked into the coloured bitumen option, but I’ve inspected some properties with a Bushmates coloured bitumen seal and it seems like even this becomes dislodged and may wash away? (See here: http://tiny.cc/3ygytz.) Certainly not as solid and stable as I imagined, unless I’ve got it wrong.

I really don’t want something that will erode and wash away quickly. I’m well aware I won’t get ages out of the above options, but I’d like at least 5-7 years before I need to think about patching or resurfacing.

I’m almost resigned to investigating asphalt, even though aesthetically it’s just wrong.

Does anyone have any insights into stabilized roadbase, stabilized decomposed granite and/or coloured bitumen spray seal on a sloped driveway??

Thanks!

[MitchellMc]

Hi @heykrazi,

To clarify, you have a roadbase mixed with some sort of local gravel which has been there for at least 10 years, and it has only been the last 12 months with the heavy rains that you've seen degradation? Can you tell if this roadbase and gravel has any binding agent or cement mixed in with it, or is it just compacted? I want to clarify this because if it is just a compacted mix, and it's lasted this long already, you would expect to get at least 10 years out of it again.

Have you considered adding any drainage to the area? The gravel has likely washed away due to a large amount of water running down the slope. Once a rut is created, the water will continue down that route, making it exponentially worse. If you can divert this into channel drains or at least reduce its volume/velocity, then you will drastically reduce the degradation of the driveway.

Cirtex PebbleLock 0.5m² Permeable Pavers are specifically designed for this type of situation and prevent aggregate migration, and heavy rain scour. You'd start by having the area graded so it's level and, in the process, fill any washed out channels. The Pebblelock would be laid down, and your choice of mediums laid over the top. The panels lock stones and pebbles securely in place but are still permeable, allowing excess water to drain through them.

Let me also mention @Adam_W to see if he has any advice.

Please let me know if you have any questions.

Mitchell

[heykrazi]

Hi @MitchellMc – thanks for your input. Here's another photo while I'm here: http://tiny.cc/4qjytz

We bought the place 4 years ago, and the driveway had some patchiness and a tiny bit of looseness back then, but yes – in the last 12 months particularly we've had the surface degrade, roadbase sediment build up in the pits and drain which are about half-way down (and now blocked), ruts form and material run off into the street. I can't be sure if it has some sort of stabilising agent in it.

Improving drainage is something we will definitely do.

The landscaper who can put in stabilised decomposed granite (or stabilised roadbase) has spoken of putting a crown in the driveway, and ensuring water runs off either side; he has also spoken of doing away with the pits and drain that are currently half-way down the driveway, and just moving all water down into the street. Decomposed granite is also somewhat porous, I think, and might that help with having less water on the surface of the driveway?

The vendor who can put in coloured bitumen 2 coat spray seal (which is a bitumen emulsion) has suggested to not have a crown, but rather slope the driveway across from right to left, so that water is directed into the lawn on the left and down the street too. Bitumen may not be porous.

Drainage is one thing, the material is another.

The stabilised decomposed granite option is a bit more affordable than coloured bitumen, and the landscaper who offers it can upgrade our edging and stone retaining wall as part of the job.

However, I've heard really mixed things about stabilised decomposed granite – some say it gets quite hard when stabilised well and can last 7+ years until more maintenance/resurfacing is required; others say that even when stabilised it goes muddy when wet and brings dust/fines into the house, especially the red granite variant.

Coloured bitumen (using an emulsion, different to cutback bitumen) is more expensive but I'd be happy to go down this path if I knew that the surface rocks wouldn't erode in the first few years – some local (non-sloped) driveways I've seen with coloured bitumen seem to have some loose material.

I just don't know which to go with!

I've looked into resin-bound driveways (such as StoneSet), but I think they are beyond our budget. I have also come across the pebblelock pavers you mention, but how would this work if we went down the stabilised DG path, for example – this would involve compacting DG onto roadbase, and doesn't involve individual loose rocks the way a traditional gravel driveway does. How might pebblelock pavers would work with a stabilised DG (as opposed to gravel) driveway?

[MitchellMc]

Hi @heykrazi,

The Pebblelock pavers would likely work in the same manner whether or not the medium is stabilised. They are designed as a method to lock materials into position and stop erosion and migration. If you're going to use a stabilised decomposed granite, then you really shouldn't need the Pebblelock. As you've noticed, there appears to be a broad spectrum of experiences with SDG. The type and quantity of binder used, whether it rained during installation and how well it was compacted, seems to contribute to the varying results.

As I don't have any firsthand experience with these resurfacing products, I cannot advise on any clear-cut decision.

Let me mention @Adam_W and @TedBear to see if they have any experience in this area.

Mitchell

[heykrazi]

Hi @MitchellMc - thanks for your response, especially on a weekend!

I'm still trying to gather more data about people's experiences with stabilised DG, or coloured bitumen emulsion (ie. Bushmates). Not easy to come by, but I'm really keen to avoid spending on something that is going to need repairing/resurfacing in a couple years.

I have also been investigating permeable paving, of which there seem to be a few types. Cirtex's SurePave, probably more relevant in my situation than the PebbleLock, is one such solution. Can you unpack for me more about how these would work in my situation?

Would I need to get my driveway roadbase re-graded and re-compacted (with a right-to-left cross-fall, for example), and then install these plastic paving cells directly onto the roadbase? or would it require some bedding layer between the roadbase and the plastic paving? how would the plastic paving cells stay on the driveway given our slope? would gravel (what kind?) then be directly applied into & onto the plastic paving layer, and would it have to be machine-compacted? 
I'm also struggling to envisage how surface gravel doesn't run off down the slope, revealing the top of the plastic paving layer...

And I'm also wondering whether, given this is a permeable paving solution, I find myself in a situation where, in a few years time, the roadbase beneath the plastic paving layer has degraded once again because of water...

I see this as an alternative to the 2 options I've been exploring to date, but need to understand more about how it might work in my context.

[MitchellMc]

Hi @heykrazi,

Here are the installation instructions and installation video for SurePave which shows the preparation steps and base materials required. You might like to also speak with the Cirtex team, as I'm sure they'll be able to answer all your questions. Since you have a sloped driveway and have seen previous degradation, it's a bit hard to determine exactly how well this product will retain the medium. I'd recommend you to have a chat with the Cirtex experts to get their opinion.

Mitchell