Air-Entraining Agents in Road Concrete Code of Good Practice and Field Experiments

Air-entraining agents are increasingly recommended as a mean to counteract the ever more severe deterioration of road cement concretes in winter. However, their use is still raising problems as far as the specifications and the practical implementation of the technology are concerned. The results of research conducted by BRRC and the conclusions drawn from it have been collected in a BRRC Recommendation ("code of good practice"). The principal aspects briefly discussed in this paper are the relations between porosity and certain mechanical properties, the characterization of air-entraining agents, and repercussions on the preliminary design of concrete mixes and on inspections on site. The views developed in the Recommendation have been tried in practice and checked against results achieved on site, among other things with three types of air-entrained concrete that were laid on the test sections of State road N255 at Herne: a continuously reinforced concrete which was to serve as a base for various noise-reducing surfacings, a 0/7-mm surface concrete, and a red-coloured concrete for a cycle track. The lessons drawn from these field experiments are presented and commented