Determination of Microstructure and Phase Composition of Sand-Lime Brick after Autoclaving Process

Abstract

The mass for sand-lime products consists of fully organic components: silica sand, quicklime and water. Depending on the proportions of ingredients used, admixtures and additives, the degree of fragmentation of the sand, and autoclaving temperatures different hydrated calcium silicates structures can arise. In autoclaved sand-lime products the following phases can be found mostly: C-S-H (I), C-S-H (II), 11A tobermorite, xonotlite and C2SH (A). Using a scanning electron microscope, the internal structure of “white brick”(common name of sand-lime products) was observed and the phase composition was examined by X-ray diffractometry. Pore size distribution was described using the most universal and most common method of analysis of the porosity of building materials – Mercury Intrusion Porosimetry. An additional component to the standard ingredients of traditional sand-lime products, lithium water glass was used. Three series of samples in the rectangular shape with dimensions 40 x 40 x 160 [mm] were prepared. The study of standard samples, with the content of 0.5% and 5.0% additives was performed in a Kielce University of Technology laboratories.