Surface dressed road useful life

[phaadu]

Does anyone have any information on the useful life of a double layer crushed stone (surface dressing) road.

 

[Ron]

It depends on what's under it! What is the double surface treatment applied to?

 

[phaadu]

The double layer surface dressing is on a 150mm laterite subbase stabilised with 5% cement and its used for a medium traffic road (75% of traffic is by 30ton trucks).

 

[Ron]

The only structural layer you have is the laterite base, and it being only 150mm thick, won't last long with the traffic you noted. I would expect frequent re-dressing will be necessary (at least monthly) and rutting will likely start in the first year or two.

 

[phaadu]

Ron, thanks for the quick response. But what is the scnenario for same road but with light traffic (50% trucks, 50% cars).

 

[Ron]

Not much different. It will last a little longer, but not much.

 

[phaadu]

Please does anyone have a table, chart or refernce to a structured means of assessing the useful life of an existing surface dressing.

 

[Debaser]

Road Note 39 (RN39) 'Design Guide for Road Surface Dressing - 6th Edition' by the TRL may help.

 

[BigH]

Debaser beat me to it . . . The cement will certainly strengthen the laterite - but you should ensure that you have a subgrade that is "adequate" - say, soaked CBR > 8 onto which to place the cement modified laterite. We have heavy haul trucks (45 tonne Volvos) on the local road here and they seem to have lasted well over the last 5 years since last surfacing - but with local potholing during the rainy season. Like with any pavements, drainage-drainage-drainage!