Ispectrum Magazine Ispectrum Magazine #06 | Page 54

try are concerned, this is a major drawback. This explains why geopolymer applications were first developed in other fields and niche markets, which do not require these types of codification. Geopolymer Moulds T.D. Volume change is the most detrimental property of cement, causing shrinkage which affects long-term strength and durability. Any suggestions specific to geopolymers, about how to overcome this problem? Dr. Davidovits To understand the long-term durability issues on geopolymers we may make a parallel with glass technologies and science. It has been recognized for a long time that there is at least a rough correlation between the dura- bility of glasses and the number of non-bridging oxygens (-Si-OH or -SiO− Me+ groups). The results of this study reveal several points that may be transferred to geopolymer structures. One is that the addition of aluminum 53 to a silicate framework generally increases durability. The importance of non-bridging oxygens on glass durability is that non-bridging oxygens provide a point of attack on a molecular scale for protons or water mole-