A novel surface waterproof geopolymer derived from metakaolin by hydrophobic modification

Protecting the surface of geopolymer is essential for improving its durability under certain exposure conditions. In this work, a novel surface waterproof geopolymer was proposed based on alkali activation of metakaolin and hydrophobic modification. The experimental results show that surface hydrophobic modification of geopolymer is completely achieved due to the increasing static water contact angle on the surface of modified geopolymer from 36 to 132 and the floating of specimens on water level after surface hydrophobic modification. Surface hydrophobic modification of geopolymer matrix obviously improves waterproof properties and reduces water absorption of geopolyrner after 28 days of exposure. This newly developed modification method will broaden the application of geopolymer from environmental and economical consideration. (C) 2015 Elsevier B.V. All rights reserved.