Carbonation of air lime mortars under natural and accelerated conditions – A systematic review

Abstract

Lime was a prominent building material in ancient times that was replaced by cement by virtue of its fast application properties. The use of lime as a construction and repair material is gaining significance recently as the conservation of heritage structures has become a concern. Moreover, the CO2 associated with the production of cement is proliferating. The use of cement mortars in repairing heritage structures did not prove to be a good choice as the composition, characteristic properties and strength were very different to that of lime binders and therefore reduced the breathability of the existing structures. Lime mortars generally react with the CO2 present in the atmosphere to gain strength and this property of lime can be employed to use it as a CO2 sink. However, the time associated with the reaction is quite high and the present systematic review focuses on the methods by which the CO2 absorption process can be accelerated. The influence of various organic and inorganic additives in accelerating the reaction in natural and high CO2 environments is critically compared. The influence of carbon curing the lime-based mortars on mechanical and microstructural properties is studied. The current review critically compares the behaviour of lime mortars in the mentioned conditions and gives an insight into the amount of future work to be done to promote lime-based binders commercially.