Lime: Resurgence of a natural building material
Er. Pawan Rana
Aligning ourselves with the pace of technological advancement has certainly benefitted us in innovating new construction materials. But, it has also strayed us from learning about our historic building materials used in the various monuments that were destroyed by the devastating earthquake of 2015. We are unable to restore our own historic monuments without international support and supervision due to lack of research in this area. Most of the palaces and buildings during the Rana regime were constructed using lime as a binding material. Today, we don’t know much about the materials our ancestors used for centuries. It is sort of a disgrace not to realize its need for the restoration of our ancient artifacts as well as to upgrade our knowledge.
Initially, clay was used as a binding material until the discovery of lime. Its use also eventually subsided after the invention of cement in the early 19th century. Thus, the human need for rapid construction and stronger binding material overshadowed the attributes of lime. Since three decades ago, people started realizing the negative impacts of cement’s impermeability in restoration of historic monuments. In contrast, the breathable and self-healing property of lime makes lime the ideal material for historic buildings, increasing its demand on the market.
In a developing country like Nepal, lime can have additional application in building low cost sustainable buildings such as straw bale houses. Also, a very low proportion of lime stabilizes the clay soil which makes it stable under water. This allows it to be used in low cost flood resilient buildings needed especially in flood prone areas of Nepal.
Acknowledging the huge benefits of lime, its need in restoration of ancient heritages and the possible contribution of its amazing carbon neutralizing cycle in the tragedy of climate change motivated us to revive the forgotten knowledge. Here at SW Nepal, we conducted initial quality tests of lime, prepared lime putty and test samples of lime stabilized soil using different forms of lime. Testing compressive strengths and hydraulic property of lime stabilized soil was a huge improvement for us. This incredible experience has sparked a sense of pride, a determination to nourish the aborning practice of lime and an inspiration to inspire young Nepalese engineers.