Granular sub base

[kjde]

I need to recommend a granular sub base which is free draining and will act as a good drainage material. Please tell me where I can source a suitable specification.

 

[Ron]

You may specify a medium to coarse durable sand (non-calcareous) having a fineness modulus greater than 2.2

This will provide large enough capillarity to prevent significant uptake from water below, and will provide adequate drainage for water from above.

 

[ganapati]

FHWA has developed guidelines for drainable pavements. Your state DOT or SHA may have information on this. There are specific gradation recommendations as well as compaction recommendations to get a permeable base without compromising the strength aspects.

 

[Jim6758]

Granular sub-grades are not so great in municipal pavements if water lines are buried beneath. A water line break can be counted on to flush the granular base out of the nearest open joint.

 

[CSainte]

What is a fineness modulus?

 

[ishvaaag]

You use a set of normalized sieves 0.16 to 80 mm and get the retained percentages for every one of them. Then you divide the sum of the retained percentages by 100, and that is the fineness modulus.

 

[raja44]

Use gravel/crushed or broken stone or combination having with finer material in the range of 25 to 50 % mechanically mixed and coslidateted to achieve about CBR30. Raja

 

[verns]

This is more a question, How accurate is the correlation between CBR am Modulus of Resilience of a subgrade material using the formula Mr=1500xCBR

 

[Ron]

Considering that resilient modulus testing is not done by many and there has not been a lot of correlative study other than SHRP, it's about as good as you'll get unless you have access to locally available resilient modulus test results.