some thoughts from Dozer
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Road gravel vs regular gravel

image dsc20775.jpgIn the continuing road story saga let me just say this — some people have this curse – everything they touch turns to s**t. 2low was in here doing some tractor work when he decided to do some road repair. I’m no expert on road gravel but I know this much — All gravels are not created equal. For road purposes you want to use road gravel — Thai would be ‘hin kuk’. The stuff (as pictured here) is absolutely marvelous. When you lay it down it is almost like paving, even if water sits right on top of it for long periods of time the road will not get muddy. It forms like a sealed hardpack surface. It is an inexpensive solution for a road which you don’t want to pave.

image dsc20776.jpgDon’t use regular gravel for a road application. You can simply check with the supplier of the raw material and tell him the specific application, he will get you the right material. You can see by comparison that the road and regular gravel look very similar. But the regular gravel won’t form a firm surface. After about a month after laying it down, driving on the road gravel will be like driving on a paved surface. Also, the regular gravel doesn’t seal as well — so it will eventually allow the mud to come through making a mess of the surface.

The road here is a little worse now than in the previous write-up. I can really see the problem with having common areas like this if you get people around who don’t know what the heck they are doing working on it. Will need to wait until rainy season to see how bad it is. In any event, a patch-up would only involve a couple of loads of road gravel — ‘the real stuff’.


  1. I will ask a pal of mine to contribute here FWIW

    He is a very handsome retired Brit professional road and bridge engineer. His profession is very similar to another pal of mine who was a metalurgist specialising in corrosion (he had a nervous breakdown because he could’nt face the fact that all his design work kept rotting away (unless made of solid gold). Similarly all my other Pal’s work kept getting washed away by monsoons and corruption

    Watch this space

    Robin T

  2. I’m afraid that my experience is that roads seem to be built as an afterthought here in the LOS. I have seen a kind of dark greyish road stone used that looked like leftovers or tailings from a slate stone quarry (maybe Khao Yai near Khorat). Of course, once the laterite dries out, it goes rock hard. My first enquiries when I went to live up country was “why don’t you have drainage ditches at the sides of the road. The local said “what a stupid idea, the trucks will slide off the road and fall into the ditch – very dangerous� Obvious really. They seem to make the roads pretty flat but the sides quickly turn into treacherous mud gullies and its very easy to get stuck. In fact a 4WD vehicle isn’t much better in such circumstances (and it costs 30% more to buy and 50% to repair when the FWD goes wrong). When the rains first come, the road surface often becomes as slippery as an ice rink. You dare not travel above walking speed in a truck. The locals often put half a tonne of sand in sacks in the back – gives all the necessary traction and stability.

    My shy friend Dr Puddle who can’t be exposed for professorial reasons (someone might shout “humbugâ€?) says the answer is DRAINAGE. Roadstone should be crushed not round (like beach pebbles). That way it has cohesive strength, drainage and wont slide about. Road drainage must be designed to flow somewhere convenient. Of course that’s the theory but we all live in the flat earth kingdom. Everyone is busy digging holes and building their houses on fill dirt so they are higher than their neighbours houses. I’ve seen a whole village raise itself half a meter. There are methods where you can jack up the upper wooden storey of a house (using Acros) and build up the ground walls to suit – not expensive.

    Where laterite roads have been tarmac’d, after about 6 months, various potholes appear which get no maintenance. At the end of the year they have become axle deep. The local OBT never keep aside any budget for on-going maintenance. A developing pothole, can be repaired quickly and very cheaply. If left untended it can develop into a sinkhole and take half the road away during monsoons. Chickens are smarter.

    Don’t ever think of using a fancy city car up country. These potholes will trash your suspension very expensively.

    What to do

    I have seen proprietary additives used in making laterite roads (I believe the technology emerged from South Africa where there are numerous low grade laterite roads). The process involves scarifying and grading the road surface, mixing in water with additive (and cement?) and then compacting the mixture. The whole process takes about 4 days and can then be covered with asphalt or concrete

    I don’t endorse any particular product as there are many available but here is one site for interested parties. Lots of good basic info on roads.

    I like the idea of a central roadstone drainage channel rather than side gutters. At least the locals can’t fill the gutters up with their rubbish and cause flooding. I might just build a 500m trial road on the farm.

    I wonder if PVA would make a good additive? You know the sort of milky glue used for wood working. It mixes well with water as an emulsion and it can be used as an additive to make waterproof concrete. What about a mix with laterite soil (which is around 50-50 mud and sand) and say 10% cement then PVA water to suit? Must try this experiment up country next month

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