INDIA, April 19, 2025 (The Hindu): Renovation of ancient structures using modern technology and materials without denting their aesthetics and historical value has always been a challenge. And when the structure is a temple as old as the Srikalahastheeswara Swamy Devasthanam in Srikalahasti town of Tirupati district, there is no room for error. The temple had been facing leaks at several spots on its roof for a long time, despite the application of concrete over the years. However, the temple management’s latest efforts, which blend age-old practices with modern technology, promise a lasting solution that also keeps the temple’s authentic beauty intact. The temple structure has a massive common roof spread over 64,000 sq.ft., covering the sanctum sanctorum of Sri Swamivaru as well as Ammavaru, besides the other celestial beings (Parivara Devathalu). An ancient roof of brick and surkhi (burnt clay) mortar is kept aloft by stone slabs. When it rained, water seeped into the temple through pillar joints and gaps in the roof stones. The issue was addressed for the first time in 2009, when a chemical coating was applied to arrest the leakages, but in vain.
Rajendra Chola I of the Chola dynasty constructed the main structure in the 11th century. Temple inscriptions also mention the contributions of Rajaditya Chola, Rajaraja Chola and Kulothunga Chola among others to this shrine.
Singed by the setbacks, the temple management consulted experts to come up with an out-of-the-box solution.
Indian Institute of Technology Tirupati (IIT-T), located 20 km from the temple, offered to provide a solution. IIT-T director K.N. Satyanarayana visited the temple in October 2021, along with professors C.V.R. Murthy and Arun Menon (both from IIT-Madras), B. Balakrishna and Prasanna Kumar Behera, both assistant professors from IIT-T.
The team cuts cores to understand the strata details of the Surkhi mortar at select points on the roof. The samples taken were sent to a laboratory in IIT-Madras.
The samples showed at least five layers of brick with lime mortar joints. As the thermal behaviour of plain cement concrete (PCC) and lime mortar are fundamentally different, the overlay of concrete over the ancient roofing led to the cracks. This was aggravated by the rusted chicken-wire mesh in the top layer of concrete. Cracks in the PCC layer led to significant rainwater seepage, which was absorbed by the brick layers.
For a pilot, the team selected the roof above the shrine of Goddess Gnana Prasunambika Devi. The concrete layer was removed and the depleted brick jelly lime concrete (BJLC), was proposed to be redone using a mixture made out of jaggery, Kadukkai (hirda) extract, Arabic tree gum, lady’s finger, jute and urad dal.