Effectiveness of tetra-ethyl-ortho-silicate (TEOS) consolidation of fired-clay bricks manufactured with different calcination temperatures

• All specimens treated with TEOS showed improvements in both mechanical and transport properties.
• The improvements strongly depend on porosity of the bricks, which strongly influences the retention of TEOS.
• Consolidation effectiveness also depends on the substrate–consolidant interaction (mineralogy).

Tetra-ethyl-ortho-silicate (TEOS) consolidation is a promising technique; however, the effects of substrate microstructure and mineralogy on the TEOS performance have not been systematically assessed; which is critical to improve consolidation efficiency. Clay bricks were manufactured in a variety of clay/kaolin proportions, calcination temperatures and treated with TEOS. by immersion. TEOS retentions between 4.9% and 5.9% were obtained, which increased surface hardness, compressive strength and flexural strength compared to non-treated specimens. Furthermore, consolidation reduced brick permeability and resulted in slight color variations. These improvements are explained by the deposition of consolidant in the pores and substrate–consolidant chemical interaction.