What is the role of the active filler in the asphalt concrete??

[msesi]

I'm currently constructing an asphalt concrete road of 5cm thick.During the design the Contractor has added 2%cement as an active filler in the mix proprortions(different types of aggregate+5%bitumen and2%active filler(cement).However the supervidsion team carriedout some mix design and found that the asphalt fullfilled all requirements without additional of active filler.In the Bill of Quantities an item of active filler is there,but to be used an authoprity must first required from the Engineer.It has been given as a Provisional sum.If this item of active filler is not incorporated in the work,will it have a decrimental effect to the asphalt concrete in the future??The road is constructed in hot areas.Please assist as the Contractor is currently pushing the Engineer to use the active filler in the production of the asphalt concrete.

 

[Ron]

Cement is generally not needed to stabilize asphaltic concrete...in fact, over the long term, it will embrittle the material. Unless you have some significantly adverse surface or weathering conditions, I would not see the need. If your area has a tenderness problem with finer gradation mixes, this might be why it was proposed; however, with an AC content of 5 percent, I doubt that you mix is overly fine.

It is used for asphalt surface treatments and as a supplement for strength in mix-in-place recycling for base materials.

 

[Zambo]

Complicated subject. And this will become more complicated due to differences between US, UK and other terminologies.

First where are you?

Second what is the bituminous material that you are using? Is it bitumen macadam, asphalt, asphaltic concrete?

 

[msesi]

Thanks Zambo for the reply,I'm in Africa the country so called Tanzania.The bitumen I'm using is asphalt 80/100