Defferennt between 80/100 and 85/100 penetration grade bitumen

[defg]

I'm currently supervising a road to be finished with a double surface dressing.The Contractor is now out of 80/100 penetration grade bitumen.He has requested from the Engineer to order 85/100 penetration grade bitumen as the previous supplier has run out of 80/100 penetration grade.Is there any detrimental effect to the work to allow the Contractor to purchase 85/100 instead of 80/100 penetration grade bitumen?Please assist.

 

[Ron]

I would be concerned for a couple of reasons:

1. The 85 penetration sounds like maybe an 80 penetration that didn't meet spec. Producers usually don't go in 5 penetration increments.

2. That's a pretty soft asphalt to start. To soften it even more will cause it to be tacky longer and will require a longer time before it weathers to a stiffer consistency to retain the aggregate.

 

[BigH]

Correct me, Ron, if I am wrong - but 85-100 is a standard AASHTO penetration grade - they don't have an 80-100 asphalt. 80-100 is typically found in SouthEast Asia - it is what we had in Laos and in India. The 85 (or 80) to 100 is the range of penetration - you need to check the actual penetration of the asphalt as delivered - it could be 90 which would then meet both specs. We found that in the hotter climates in India the specs called for 60-70 but really should have gone to 40-50 (which we wanted) but our specs wouldn't allow it - ended up using crumb rubber (not overly happy with it) or polymer modifiers (seemed to hold up much better). defg didn't indicate geographic location - likely is in Asia (?) but would be buying from US (?) on the 85-100.

 

[Ron]

BigH...you are correct. I had not seen the 5 penetration increment, just the range you noted. I re-read my post and noticed I had the out of spec backwards! Under our spec, it would be the 80 that is out of range.

Not familiar with SE Asia requirements, but as noted, the 85 would be within tolerance if defg is in SE Asia (and actually be within tolerance if in US, though the 80 would not.

I can't imagine he would be using that in a hot climate, though. Here in the SE USA, that asphalt would flow into the next county.

 

[defg]

Hi BigH,
Thanks you for the post.The geographic location of the project is Africa(Tanzania).The project road is located in a moderate climatic zone.The bitumen materials(85/100)is expected to be brought from Saudi Arabia or Iran.

 

[BigH]

Get copies of the Overseas Research Notes ORN-3 and ORN-31. They have charts on the appropriate bitumen to use for chip seals - which would have some validity, I believe, for HMA. Being in Tanzania, you might actually be using it for chip seals.(?) The main thing is to get the viscosity correct - you might need to treat with kerosene.