I am planning to construct a ‘pathway’ around our newly built house in Northeastern Thailand – it’s more for stopping mud splashes to the house render than for regular walking on. The new driveway should be strong enough for occasional 10 ton delivery vans.
Labour is cheap and enthusiastic (the fit working men of my wife’s family proffered work at slave wages of £3 a day and were delighted when I said £5 – still feel a bit guilty!). Stone is cheap at £4 /tonne ex quarry. Haven’t priced ready-mix concrete yet, but likely to be a third of UK prices.
I’m DIY’ing it mostly because my wife wants to give her family work and partly because I’m not impressed with the quality of paving I’ve seen in Thailand – other than on major roads. The answer here seems to be to use lots of the same small stone (about 40-70mm) and then bung a big wedge of concrete on top.
The house sits on quite a high plinth and the original garden level has had to be raised significantly with topsoil. Unfortunately the soil filling took place while I was back in the UK, so now I am paying the family to dig some back out again for the driveway and path!
For the driveway I plan to build up the level (as deep as 1 metre) back to the new garden level with a capping layer of crushed stone – irregular stuff that varies from 50mm to 200mm. On top of that a 150mm sub-base of DTp1 (or the nearest I can get to it). On top of that 150mm of concrete – reinforced with fibre if they sell that here.
My questions are: (1) Is it essential to dig down below the original soil level? The land was fallow for 20 years and the topsoil is rock hard so I am hoping the answer is no. (2) When rolling the capping layer, should I do this in layers of say 3 x 330mm or 2 X 500mm? (3) Do I need to place something on top of the capping layer to stop the sub-base filtering down through it? I am not sure I can find fancy geo textiles locally if that is the answer: can I alternatively put a thin layer of concrete between capping and sub base or is that an unnecessary extravagance? (4) is it essential to put a damp proof membrane between sub base and concrete? Again, I’m not sure whether I can get it easily here.
For the pathway the new level will vary between 150 and 400mm high above the original soil level. (1) Having already dug that out can I get away with using just a sub base of varying levels of 75 to 325mm or must I put in a capping layer for the deeper areas? (2) The concrete slab will be 75mm. Again – DPM essential? (3) Is it necessary to put an insulation/expansion joint (fibreboard) between the house and the pathway and should the (1300mm wide) pathway have joints at 3m intervals? (4) I can’t yet find a whacker machine for hire and don’t think a roller will get to much of the pathway, due to aircon units and other sticking out bits. Does 25 people jumping on the sub base for a couple of hours do the same trick? That was tongue in cheek, but seriously what were the old-fashioned techniques?
My attempts to explain a sub-base spec - DTp1 or ‘40mm to dust’ - to quarrymen, in pidgin Thai and using my wife as interpreter, failed miserably! The best I can do is to get them to mix 3 or 4 grades of stone (including dust) – probably rather badly - at the quarry. Any comments on slightly less effective but easier mixes? My local quarry has sizes 1 to 10 with 10 being the 50-200mm material and 2 being the 40-70mm stuff. (All of this is my layman observations from inspecting the piles). I have not seen it yet, but I am assuming that 0 is dust.
I’ll save the questions on curing concrete in 80-95 degree temperatures until I’ve searched your excellent web-site further, but if anyone has experience of doing this kind of job in warm expatriate conditions I would love to hear of it.
Concrete driveway and paths in thailand - Comment on my plans please
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