First Experience of Noise-Reducing Exposed Small Aggregate Concrete Surfaces in Japan

In Nagoya, Japan, for a national highway having a large-scale common duct set under the road, concrete pavement with transverse brooming has been adopted in order to ensure structurally durable pavements. However, because these roads are located in an urban area, demand for less noisy pavements has increased. Therefore, in the project from 1994 to 1995, exposed small aggregate concrete surfaces were adopted experimentally, based on experience in Austria. The features of this concrete pavement that are different from other exposed small aggregate methods, are as follows: I )Reinforced doweled jointed concrete pavements by manual placing and consolidation, 2) Vacuum treatment soon after concrete consolidation in order to generate early strength, 3)Two types of retarding methods: by placing a retarding paper sheet or by the traditional spraying of a liquid retarder. This paper describes considerations for the mix proportion suitable for vacuum treatment and the exposed aggregate technique, construction methods, measured tireirnad noise and related surface characteristics.