Kalidas Jethabhai House - From Research to Restoration: Crafting Lime Plaster for Conservation

The previous study by Conservation and Regeneration Master's students, Jigar Rathod and Shriram R M, looked into the lime used as a binding material in construction of KJH (Kalidas Jethabhai House). Investigation was carried out using techniques like XRD, XRF, FT-IR, FESEM, and checking binder-aggregate ratio. The study revealed that most materials were from nearby and hydrated lime was used.

For fixing and restoring the plastered walls, we tried different mix designs and various additives to match the existing building materials. Followed by testing the mixes for their strength. Matching properties is crucial for maintaining the authenticity and integrity of heritage structures and thus providing a compatible repair material for conservation works.

After identifying the nearest proportion and mix design of 1:1.5:1.5, which means 1lime: 1.5 Pozzolanic material (Surkhi): 1.5 Sand, we started removing the plaster wherever it is required to repair the surface. This step was carried out after inspecting the existing plaster of the wall and noting the later done cement patch repairs.

Creating the perfect three-layer lime plaster was a journey we documented step-by-step. First up, we carefully mixed our raw materials based on our test results. This was our foundation. Next, we applied the base layer - a 5mm thick coat of lime plaster. Keeping it moist with gentle spritzing, we let this layer solidify over a few days. Building on this, we added the second, thicker layer (10-12mm) and repeated the curing process. Finally, the finishing touch was a 4-5mm topcoat made from a special mix. After a week of careful curing, our three-layer lime plaster masterpiece was complete.

A thorough documentation process, archival research, material mapping, sample collection and material characterisation led to a compatible lime-based repair material for the conservation works of Kalidas Jethabhai House. This process also reflected a multi-disciplinary approach involving professionals from various fields as well as masons who gave valuable inputs during the mix design trials.