Most New Zealand pavements comprise a granular base with a thin bituminous surfacing. When bituminous mixes are used for this surfacing, the predominant failure of the pavement is caused by fatigue cracking. A review of literature was made in 1993 to identify those products that could have the potential to be used to improve the fatigue life of thin bituminous mixes for surfacing roading pavements in New Zealand. the effects of modifiers on the fatigue resistance of thin bituminous mixes are included.
The most appropriate mode of laboratory testing is that which includes:
Polymer additives could be successful when used in soft bitumen, but the effect of adding fibres is unclear.
The fatigue resistance of modified bituminous mixes had been investigated and were reported in the literature reviewed, but the modes of testing did not cover the range of conditions that apply to New Zealand pavements. Therefore none of the modifiers tested could be used with confidence in this country, although a number of modifiers appear to have the potential to improve the fatigue life of thin surfacing mixes.
Keywords: Bitumen, bitumen modifier, bituminous mix, fatigue, fatigue life, New Zealand, pavements, pavement layers, roads