The 1,250-year-old Kailasanathar Temple in the town of Uthiramerur, one of the oldest temples in the Indian state of Tamil Nadu, is in danger of collapse. Its 80-feet-high dome has developed cracks as much as three feet wide. The thick pelt of vegetation covering the dome makes conservation difficult, and there is very little government to be had for restoration projects. In a country bristling with ancient monuments, the Indian government preserves just 5% of them.

Indian heritage conservation organization REACH enlisted engineering experts from the Indian Institute of Technology, Madras, to examine the foundation of the temple and determine what, if anything, could be done with limited funds and care for historical integrity.

When the monument was examined it was found that a few stones in the sub-structure were dislodged from their original position, and there were several cracks in the plinth due to stress, strain and shock says Anu Padma, who was involved in the conservation project as a research scholar.

“In Uthiramerur the options were limited. If the broken stones are to be removed and replaced, the restoration process would have become very complicated and could have further damaged the temple dome,” Dr [MS Mathews of the civil engineering department at IIT-M] said. […]

So the team at IIT-M decided that “granite stitching” would be the most simple, least invasive and the necessary method to restore the temple to its original glory, Dr Mathews said.

The site observation and inspection showed that the cracks in the granite stones were “non-progressive” and laboratory tests were conducted to assess the load-bearing capacity of stitched granite beams in comparison with the solid, uncracked granite beams.

“Test results proved that the stitching would bear the desired load,” Ms Anu Padma said.

Granite stitching is a technique that uses steel rods and epoxy to pull two sides of a crack back together. Restorers drill a diagonal hole (at approximately 45 degrees) that passes through both sides of the crack, remove the granite dust and chips, then pump the hole full of an epoxy grout. Then they insert a grooved stainless steel rod into the drilled tunnel and fill in the holes with some of the granite dust removed after drilling. The rod is embedded in both sides of the rock, effectively sealing the granite back together just like a stitch in a piece of clothing, and without any unsightly visible supports.

It’s an inexpensive technique but because they were applying it to an ancient structure, experts ensured that they used the highest quality materials. The stainless steel rods have a high percentage of chromium which will keep them from corroding for at least 500 years. Hopefully somewhere in those five centuries there will be proper funding and care for India’s ancient monuments so those rods won’t be stretched to their limits.

Once the foundation was stabilized, restorers turned their attentions to the superstructure, repairing the dome and its elaborate figure carvings out of a limestone plaster based on the ancient formula.

You can find some pictures of the restoration in REACH’s flickr account.