A Comparative Study of the Effects of Silica Fume, Metakaolin and PFA on the Air Content of Fresh Concrete (April 27, 2000) A Comparative Study of the Effects of Silica Fume, Metakaolin and PFA on the Air Content of Fresh Concrete (April 27, 2000) View PDF To Purchase or Inquire You can purchase Silica Fume or Metakaolin in bags, super sacks, or bulk shipments. Connect with Us to Get Started