Noise protection barriers by concrete two-layer panels

In this paper protection of residential areas located near asphalt mixing plant in Zagreb (Croatia) from industrial noise is presented. The concrete wall as noise protection barrier formed by two layer panels was applied and built in February 2007 year. Two layer concrete panels consist of reinforced concrete slabs (with static function) and a sound-absorbing layer of lightweight porous concrete (on the noise source side). The short-term noise level measurements before and after the construction of the barrier were performed. Noise level measurements after the construction of the barrier were carried out at the same time in front of and behind the barrier using two sound-meters. In that way the effect of the applied protection was determined more precisely. The result of measurements on the site compared with the result of calculations and very good agreement was obtain.