SiO_2 Powders Synthesized via Sol-gel as Pure Raw Material in Geopolymer Preparation

摘要

Geopolymers are inorganic aluminosilicates mainly proposed as environmentally friendly building materials, which are obtained by alkali activation of natural minerals, calcined clay (e.g. metakaolin) and other aluminosilicate sources. The wide range of chemical and mineralogical compositions of these raw materials influences several properties of the obtained geopolymers. In the present work, pure SiO_2 powders were synthesized via sol-gel technique and proposed as pure silicate sources to prepare alkali activated geopolymers (30, 40 and 50 wt%) through the geopolymerization process in order to improve the physical and chemical properties. The consolidation of the geopolymeric matrix containing the pure SiO_2 gel was followed by pH and conductibility until 28 days. FT-IR and mechanical analysis was performed to follow the structural modification of the materials. Moreover, compressive tests were performed to determine the mechanical properties of the mixtures.