microstructure.
Nowadays, lightweight construction materials are used to
reduce the weight of building structures and improve thermal insulation
efficiency of buildings. This study, therefore, focused on the
synthesis of lightweight geopolymer. Suitable lightweight source
materials containing silica and alumina such as diatomaceous earth
(DE) and rice husk ash (RHA) are available in large quantity in
Thailand. DE contains both silica and alumina and RHA contains
mainly silica. They both have very high specific surface but particle
morphologies are very different. DE is a sedimentary rock consisting
principally of highly porous skeletons of diatom, in other word,
a loosely packed mineral. The porous silica structure gives DE useful
characteristics such as unique particulate structure, low bulk
density, high absorptive capacity and high surface area [4]. The
deposit of DE in Lampang province in the north of Thailand is quite
large estimated to be in excess of 100 million tons. The mineral
composition consists primarily of silica with some clay minerals
viz. montmorillonite, kaolinite and muscovite. DE could readily
undergo chemical reaction whenmeetsCa(OH)2 resulting information
of strong binding phase [5]. These clay minerals render DE as a
suitable feedstock materialfor geopolymer synthesis. RHA contains