Evaluation of the pozzolanic activity of the earth of Datça as a building material

Durable building materials that use local raw materials and have relatively low energy input, low emissions, and low cost must be produced to counter the problem of an acute need for qualified housing in Turkey. The pozzolanic activity of volcanic tuff settled at the far west end of the Datca Peninsula is determined, and the effect of lime/pozzolan ratio (L/P) (L/P 30, L/P 35, L/P 40) and various curing conditions on the properties of the L/P mortars is investigated. The increase of pozzolan content in the mixture slowed down the pozzolanic reaction rate during early stages but resulted in a higher compressive strength at longer ages. L/P 35 has the highest pozzolanic reaction rate when both hot and moist conditions are maintained. Elevated temperature curing at 55°C, 70°C and 90°C accelerated the pozzolanic reaction rate and has significant effect on compressive strength development; however, above 70°C, the material becomes brittle and vulnerable to flexural stress due to the excessive drying. Air curing in 23°C and 65% relative humidity (RH) is not suitable to achieve sound material in comparison with more suitable conditions of higher RH for hydration of calcium silicates. In contrast, physical characteristics of the mortar develop considerably with water curing, which characterizes the material as hydraulically hardened. It has been proven that, by incorporating necessary hardening and consolidation processes, it is possible to make mortars as well as bricks similar to high-quality calcium silicate ones by using the earth of Datca and lime containing calcium silicate.