製紙工場排出粉じんによる屋根瓦の腐蝕とその機構に関する基礎科学的研究(第2報)

Abstract

This report deals with two data, one of which relates to the breaking test of roof-tiles of the three huts mentioned in the previous report, the other being concerned with some laboratory experiments performed, with the intention of acquiring further knowledge, using tiles purchased from supply houses between Nov. 1981 and Jan. 1982. The results are as under : As regards the breaking test, it was found that (1) the strenght of tilles runs parallel to Na_2SO_4 amount in them, the higher the latter the stronger being the former. (2) The strength of the tiles which had been exposed southward is lower than that of those exposed northward. Concerning the laboratory experiments, it was discovered that (1) both water and aqueous Na_2SO_4 solutions, if absorbed into tiles and held there as such, affect their strength in such a complicated manner that capillary and tensile forces of liquid might reduce the strength while liquid existing as filler in tiles could enhance it. (2) The penetration of liquid into tiles is completely arrested by the smoking-formed layer, this being in marked contrast to the finding that, with old-fashioned tiles of the 1960s type, they permit Na_2SO_4 solutions to penetrate almost freely.