Living mortars-simulation study on organic lime mortar used in heritage structures

The study explores the effective role of fermented plant extracts in hydraulic lime mortars towards the bacterial precipitation of calcium carbonate. Two frequently used plant extracts that are rich in carbohydrates, jaggery (unrefined sugar) and kadukkai (Terminilia chebulia) are fermented with and without lime for seven days in semi aerobic condition to study the end products and its possible interaction in lime mortar. The lime added fermented liquid has initiated the growth of Bacillus subtilis with a greater yield of lactic acid, ethanol and CO2 as compared to fermented liquid without lime. Analytical techniques like XRD, FESEM and TGA-DTA were used to study the hydrated phases and microstructural behaviour of the hydraulic lime mortars prepared with the above fermented liquids. The interaction of lime added fermented liquid with hydraulic lime has resulted the bio-precipitation of calcium carbonate polymorphs by Bacillus subtilis and enhanced the internal carbonation by absorption of carbon-di-oxide supplied by organics and shown greater compressive strength and bulk density in contrast to reference mortar.