Jaehun Ahn, Jinwoo Jung, Seungbae Kim, and Shin-In Han. “X-RAY IMAGE ANALYSIS OF POROSITY OF PERVIOUS CONCRETES”. GEOMATE Journal, vol. 6, no. 11, Mar. 2014, pp. 796-9, https://geomatejournal.com/geomate/article/view/2948.