Fig. 5
From: Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

Measured shrinkage due to heating. a The volume ratio of scoriae after (\(V_{\mathrm{f}}\)) to before (\(V_{\mathrm{i}}\)) heating as a function of the heating duration. The symbol color indicates the furnace temperature at the end of heating, and the symbol size indicates the initial volume of the scoria. b The porosity change due to heating. Each set of circles and crosses connected by a line indicates the porosity change of a scoria before and after heating, respectively, as a function of the furnace temperature at the end of heating. The symbol color indicates the heating duration, and the symbol size indicates the initial volume of the scoria