Abstract
Compressive strength of natural welded-tuff and artificial welded-tuff was measured. The artificial welded-tuff was made by slight welding of natural welded-tuff by a sintering method. Both welded-tuffs made of same material showed same compressive strength for the same porosity. In view of the above facts the most reasonable conclusion is that the structure of the artificial welded-tuff is equal to that of the natural one, and therefore, the sintering equation (Eq. 1 in the text.) is available for the studies of natural welded-tuff.
