Impact of mica content on water sensitivity of asphalt concrete

It is well known that mineral fillers have an important influence on the performance of bituminous mixtures. Properties of filler are depending on the type and the nature of mineral filler. Experience has shown that presence of mica in the filler material has reduced the asphalt concrete resistance against water influence and freeze and thaw cycles. The purpose of the present work is to clarify the effect of free mica in the filler material on the durability of bituminous mixtures. Presence of free mica results in a tremendous increase of the total surface area of aggregate, which is intended to be covered by a bitumen film. It is concluded that making mix design in respect to surface area of the filler will almost vanish the disadvantage of using mica in production of asphalt mixtures. It will also result in using less amount of mineral filler.