PERFORMANCE AND DURABILITY OF BITUMINOUS MATERIALS. 13: PERFORMANCE ASSESSMENT OF SPANISH AND BRITISH POROUS ASPHALTS

Porous asphalt is currently gaining in prominence in the UK after recent legislation that will help in enhancing its use to a level comparable to that in other European countries. In Spain, porous asphalt has been used extensively and has a well established performance record. The material is predominantly designed with the aid of the Cantabro Test, developed originally at the University of Cantabria and is based on the abrasion loss undergone by specimens after being rattled in a Los Angeles machine without the steel balls. In the UK, apart from the Binder Drainage Test propounded by the Transport Research Laboratory and which is conducted on uncompacted mix specimens, there is no laboratory tool which can be used to aid in porous asphalt mix design. This paper attempts to arrive at a mix design method which takes into account the parameters referred to above which address the limitations of porous asphalt, namely strength, porosity and durability. Non destructive tests for the determination of the elastic modulus and permeability have been proposed to make maximum use of the prepared samples before introducing them to a Cantabro-like test for abrasion loss determination. Porous asphalt grading specifications from BS 4987 have been adopted and designed according to the proposed method. The performance of these mixes was then compared to that of mixes designed according to the Spanish specifications and inferences made thereof. Recommendations for further refinement of the method have also been made. (A) For the covering abstract see IRRD 875331.