The use of open graded asphalt wearing courses for highway pavements is established technology but the opportunities to use a similar cementitious based surface type for concrete pavements has been limited by material technology and costs. Research work in Australia using new generation concrete admixtures and placing techniques has allowed the development of a stiff open graded concrete material which is expected to meet the same durability requirements as standard concrete used for roads. Open graded surface textures absorb vehicle noise emissions and minimise water film build up during rain events, thus resulting in quieter and safer driving conditions. In addition, experience has shown that high void contents at the surface assist in reducing water spray generation and glare reflection. This paper details the laboratory mix design test results and three field trials using hand placing techniques to define the limits of a wet on wet construction process. The concrete developed in the trials has high compressive strength with air voids in the range of 20 to 30%. The next stage in the development of the open graded concrete surfacing is in the use of mechanised placing techniques to make the process cost competitive to other asphalt alternatives and yet meet similar durability requirements to those currently expected in concrete road surfaces over a 40 year design period.
Read full abstract