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AallRounder5 Sep 2013 06:42Hello Orschel,
for driveable paved paths, a 20 cm (8 inches) thick gravel layer as a base course in the grain size you mentioned should be installed beneath the bedding layer. However, below that, there must be a frost-protected substructure (also called the sub-base) to prevent your paving from heaving during freeze-thaw cycles. For this, the topsoil must at least be removed and replaced with, for example, 0/32 gravel compacted in layers. The frost depth varies depending on the region and is typically between 80 and 120 cm (31 and 47 inches) in my view.
It’s best to obtain the technical specifications from the paving manufacturer. There you should also find precise recommendations for the bedding and jointing materials as well as the installation process. Recommendations can vary quite a bit.
Regards
AallRounder
for driveable paved paths, a 20 cm (8 inches) thick gravel layer as a base course in the grain size you mentioned should be installed beneath the bedding layer. However, below that, there must be a frost-protected substructure (also called the sub-base) to prevent your paving from heaving during freeze-thaw cycles. For this, the topsoil must at least be removed and replaced with, for example, 0/32 gravel compacted in layers. The frost depth varies depending on the region and is typically between 80 and 120 cm (31 and 47 inches) in my view.
It’s best to obtain the technical specifications from the paving manufacturer. There you should also find precise recommendations for the bedding and jointing materials as well as the installation process. Recommendations can vary quite a bit.
Regards
AallRounder
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AallRounder9 Sep 2013 11:50Hello Orschel,
Both quartzite and basalt are very strong and wear-resistant natural stones. Such a base layer is a real luxury compared to recycled concrete aggregate (RCA). If you have a low-cost local supplier, run the numbers, also in comparison to RCA. Functionally, natural stone and RCA gravel of the same grain size should make no difference as a base. In my opinion, the decision mainly comes down to cost. For both, ask for the particle size distribution, including the fine material content. The fine material (grain diameter < 0.063 mm) should not exceed 5% by mass, otherwise the water permeability will be too low. This is a general guideline; the technical specifications of the paving manufacturer may set different requirements. With RCA, the proportion of crushed brick should also be low, as brick acts capillarily—even in crushed form.
For the bedding layer, follow the manufacturer’s specifications, as I already mentioned. For paving bricks and travertine, for example, crushed stone is recommended, while for concrete pavers you can possibly use paving sand instead (price!). If you expect ant problems, crushed stone would be better, because these small persistent insects cannot move it around and, frustrated, won’t settle there. You surely know the look of paving joints regularly disturbed by ants.
A crushed stone without fines—as offered to you with 2/5 (grain size)—has very high permeability but is harder to compact. This is also called “eco-laying.” In my view, this would only be an option if the base layer were poorly permeable. With 80 to 100 cm (31 to 39 inches) of mineral mix / RCA, it should be fine, because with proper slope, only a fraction of the rainfall infiltrates through the joints.
Bedding and joint material must be coordinated—e.g., a bedding made from 2/5 crushed stone and joints from 0/5 sand is poor practice because the joint material will fall into the bedding. Mixing layers must always be avoided! Also, the so-called filter stability must be considered, meaning there must be no waterlogging at any layer interface in the overall structure.
What surface material have you chosen? What does the manufacturer specify for the bedding and joints?
Regards,
AallRounder
Both quartzite and basalt are very strong and wear-resistant natural stones. Such a base layer is a real luxury compared to recycled concrete aggregate (RCA). If you have a low-cost local supplier, run the numbers, also in comparison to RCA. Functionally, natural stone and RCA gravel of the same grain size should make no difference as a base. In my opinion, the decision mainly comes down to cost. For both, ask for the particle size distribution, including the fine material content. The fine material (grain diameter < 0.063 mm) should not exceed 5% by mass, otherwise the water permeability will be too low. This is a general guideline; the technical specifications of the paving manufacturer may set different requirements. With RCA, the proportion of crushed brick should also be low, as brick acts capillarily—even in crushed form.
For the bedding layer, follow the manufacturer’s specifications, as I already mentioned. For paving bricks and travertine, for example, crushed stone is recommended, while for concrete pavers you can possibly use paving sand instead (price!). If you expect ant problems, crushed stone would be better, because these small persistent insects cannot move it around and, frustrated, won’t settle there. You surely know the look of paving joints regularly disturbed by ants.
A crushed stone without fines—as offered to you with 2/5 (grain size)—has very high permeability but is harder to compact. This is also called “eco-laying.” In my view, this would only be an option if the base layer were poorly permeable. With 80 to 100 cm (31 to 39 inches) of mineral mix / RCA, it should be fine, because with proper slope, only a fraction of the rainfall infiltrates through the joints.
Bedding and joint material must be coordinated—e.g., a bedding made from 2/5 crushed stone and joints from 0/5 sand is poor practice because the joint material will fall into the bedding. Mixing layers must always be avoided! Also, the so-called filter stability must be considered, meaning there must be no waterlogging at any layer interface in the overall structure.
What surface material have you chosen? What does the manufacturer specify for the bedding and joints?
Regards,
AallRounder
Wow, that’s an excellent answer. Thanks a lot for that. Right now, I’m generally just gathering information and exploring what options are available and what we need. That’s why we haven’t finalized the surface material yet. But the advice about using the same grain size for both the paving bed and the jointing material sounds very reasonable! Otherwise, we live on the edge of a field in a village, and ants have already settled in the soil mounds in the garden, so I assume they could also appear at the front...
However, when I compare RCL with basalt/quartzite, honestly, I prefer to choose the better material and pay a bit more instead of opting for recycled material. It’s only about 30 m² (320 ft²), so frankly, I don’t want to cut costs in the wrong place, but I will definitely do a price comparison just to be sure!
However, when I compare RCL with basalt/quartzite, honestly, I prefer to choose the better material and pay a bit more instead of opting for recycled material. It’s only about 30 m² (320 ft²), so frankly, I don’t want to cut costs in the wrong place, but I will definitely do a price comparison just to be sure!
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AallRounder9 Sep 2013 13:32Glad to hear this is helpful to you. Maybe we can also consider the topic rating...
It’s enviable that you have such affordable suppliers for natural stone gravel. I have to pay twice as much compared to RCL for something like that. It really depends on the region.
“Only” 30 sqm (323 sq ft) is nearly 30 cubic meters (39 cubic yards) if you replace it at 1 m (3.3 ft) frost depth. That easily amounts to 50 tons (55 US tons)!
Or do you plan to skip a frost-protected foundation and only install the 20 cm (8 inches) base layer? That is only done if the subsoil is already more or less frost-free, meaning little fine-grain soil, no clay, no loam, etc. Calculate the cost per ton for that!
It’s enviable that you have such affordable suppliers for natural stone gravel. I have to pay twice as much compared to RCL for something like that. It really depends on the region.
“Only” 30 sqm (323 sq ft) is nearly 30 cubic meters (39 cubic yards) if you replace it at 1 m (3.3 ft) frost depth. That easily amounts to 50 tons (55 US tons)!
Or do you plan to skip a frost-protected foundation and only install the 20 cm (8 inches) base layer? That is only done if the subsoil is already more or less frost-free, meaning little fine-grain soil, no clay, no loam, etc. Calculate the cost per ton for that!
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