A CONSIDERATION OF CONSTRUCTION METHODS OF THE HARIO RADIO TOWER COMPLETED IN 1922 THAT HAS BEEN DESIGNATED AS NATIONALLY IMPORTANT CULTURAL PROPERTY

Abstract

 The construction of the Hario Radio Tower commenced in 1918 and was completed in 1922 by the former Imperial Japanese Navy, which came to recognize the importance of radio communications during the Russo-Japanese War. While the deterioration of concrete structures has recently become a serious social problem, this radio tower, which was constructed approximately 100 years ago, maintains its integrity without cracks or rebar corrosion. However, except for a few extant photographs depicting the construction’s progress, we have no clear picture of the construction methods used. Nevertheless, it is necessary to pass on to future generations the construction techniques used to build this precious heritage. From an analysis of these photographs, phenomena remaining on the concrete surface, and documents of the period, it became clear that the tower was built while moving the external suspended scaffolding vertically; the concrete was compacted using the pounding “tsukikatame” method that employs medium-consistency concrete. Furthermore, the study verified that this pounding method produces dense concrete and is effective for suppressing carbonation.