Possibility of using Kütahya Volcanic Tuff as building stone: Microstructural evaluation and strength enhancement through heat treatment

• Heat treatment of low strength tuffs for using it as building stone was evaluated.
• Corundum and leucite were formed at 1200 °C.
• Homogeneous distribution of micro crystalline structures enhanced the strength.
• Heat treatment enhanced the uniaxial compressive strength of tuff from 7 to 47 MPa.
• Estimated costs for heat treatment of tuffs (5–8 $/m3) were found feasible.

Tuffs undergo physical, mineralogical and microstructural changes after heat treatment (HT). This study presents (i) characterisation of Kütahya Volcanic Tuff (KVT), (ii) effect of (HT) on its above mentioned properties and (iii) cost analysis of the HT. Corundum and leucite were formed at 1200 °C. According to SEM observations, homogeneous distribution of micro crystalline structures and densification of the structure enhanced the strength of KVT considerably. HT of bulk KVT provided them the required strength for building stones, with reasonable cost and maintaining their natural and aesthetic appearance.