Efffect of Wax Content on HMA Behaviour

[BigH]

Hoping that someone in the group our from the group member's personal network can help direct me to the effects of wax content on the behaviour of HMA after placement. Bitumen is 60-70 pen straight from refinery - no modifiers, low softening point (about 46degC).)

 

[iandig]

By HMA do you mean Hot Melt Adhesive?
I have copied below an explaination of the role of wax in a HMA (Hot melt adhesive), but I am not convinced yet that this is what you are looking for.
The role of wax in hot melt adhesives:
1.The low viscosity of the wax is used to reduce the high viscosity of the polymer and resin to ensure efficient mixing. This reduction in viscosity is particularly important during the application stage. A low viscosity is required to pump the molten adhesive from the storage tank to the application area and to ensure proper surface wetting when applied.
2.The degree of crystallinity and the congealing point of the wax in the adhesive formulation control the open and set times of the HMA, as well as the flexibility and elongation properties.
3.Wax plays a major role in increasing the blocking point of the final adhesive, preventing the adhesive pastilles from sticking together during transport and storage.
4.The high temperature properties of a hot melt adhesive are largely controlled by the melt range of the wax being used.
A typical HMA contains 10-30 % wax.

 

[BigH]

Ian - you can tell you ain't a "Yank"!! Sorry - HMA is hot mix asphalt (HMB in UK??). Any help you can find would be appreciative.

Got home in time to see the 6-Nations match (replay) of England and Ireland. What a hell of a game! England came so so close a number of times but just lacked the ability to put it across - of course, I think the ref screwed up the one try and discounted it. Hard hitting at its best - but commentators were lamenting the lack of push in the standing mucks. Still I enjoyed it; the Scotland-Italy game was boring.

 

[iandig]

To be honest Howard, we were never going to win - Two tries disallowed for no good reason and turnovers given against the run of play. We tend to take our Rugby quite seriously (thats what you get for living in Rugby!!) and we also sponsor one of the rising stars at Leicester Tigers.
As for the wax in the mix, I know it can be used as an additive in order to reduce the viscocity at lower temperatures prior to laying (hence Warm Mix Asphalt WMA - but I am sure you know this already) As for the long term effects, I would need to refer to one of the oracles I know in the pavement/bitumen research institues I know. Are you looking for the [potential] long-term effects on the stiffness/durability/life-span, and if wax was added is it not a WMA in stead of a HMA? I havn't played with the balckstuff for over a year now, and in this industry that can be a long time!

 

[BigH]

We've been having a lot of flushing - and other problems. Bitumen in India is not the best quality. Our softening point for 60-70 straight pen is 46 to 48 and it should be upwards to 53 to 55. Indian bitumen is also waxy - there is a limit on the wax content - but I will have to get it from work tomorrow - anyway, we meet the limit. One of the reasons that one "expert" was implying that would cause the flush is the wax content. Details tomorrow. By the way, when we were in London in October, I bought an English rugby shirt!