Cracking and Autogenous Healing in Stonework

Our clients occasionally ask us about the small, hairline cracks that have appeared in their cast stone designs.

Cracking like this is a common occurrence in both natural and cast stone, and does not affect the structural integrity of the piece.  What’s more, the fascinating, naturally-occurring process of autogenous healing helps to heal these cracks.

In this blog, we explain more about the cracking of stonework and how autogenous healing helps to heal it.

Why do cracks appear in stonework?

The appearance of cracks and hairline cracks (or fissures) in natural and cast stone is a common occurence. In the case of cast stonework, cracking is not a sign of inferior stone or poor quality casting.

Do cracks in stonework affect its strength?

No.  Cracking in nearly 100% of all cases is not detrimental to the cast stone material holding together, or the structural integrity of the cast stone design.

When does cracking occur in stonework?

Changes in temperature can increase the likelihood of natural and cast stone cracking.  For example, periods of very warm weather, followed by very cold weather forces both natural and cast stone to expand and contract.  This can result in the occurrence of hairline cracking.

What is autogenous healing?

Autogenous healing is a common process whereby hairline cracks, often found in cast stonework, are healed by a natural process activated as a result of the rainwater seeping into the limestone.

How does autogenous healing occur?

Autogenous healing occurs when rain water seeps into the cracks found in natural and cast stonework.  Over time, the movement of rainwater, through the surface of the stone dissolves the free lime, which is deposited in the micro crack as the water evaporates.

This starts a process of reaction whereby the lime subsequently reacts with the carbon dioxide in the air and is converted to calcium carbonate.  This cementitious reaction effectively binds the stone together again and the cracking is healed.

Does autogenous healing effect the structural integrity of stonework?

No.  We have seen the autogenous process take place on some of the cast stonework in our Show Gardens and those purchased by our clients.  We have seen that our Home & Garden ornamental cast stone designs and our Building & Construction architectural stonework have not been structurally impacted by autogenous healing.

Need Some Additional Help?

Our Home & Garden team has years of cast stonework knowledge.

They will be more than happy to discuss any queries you may have about autogenous healing and how it can effect our stonework.

Call our team on 01604 770711 or arrange a call back at a time that works for you.

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