Carbonation and durability of construction materials

Lime has been used for a very extended time in history as a binder in lime mortar which helped passed civilisations to realize still existing, useful and splendid constructions in many places in the world. The hardening of lime mortar is depending on the carbonation process. Extensive studies have been done on carbonation of lime and the influence of it on the properties of lime mortar and on masonry made with it. Models have been made that explain the speed of the progress of carbonation depending on the physical nature of the mortar which has an influence on the diffusion of carbon dioxide through the porous mortar medium and the interaction with water has been taken into account. The reaction speed of the carbonation reaction has been studied and variables that influence the chemical reaction has been identified amongst others using X-Ray diffraction analysis in an ongoing carbonation experiment. It contributed to understanding the relation between carbonation conditions and the nature of the reaction products that can be amorphous or have different phases of calcium carbonate. Next the hindering factor in the acceleration of carbonation has been studied and different additives are being studied to investigate their possible impact on this hindering factor. Carbonation is also studied in other building materials that contain Ca(OH)2 in its composition or as a reaction product. This is the case for cement mortar or concrete. Recent research however has also “used” the carbonation process to instigate a binding process, for example using alkaline slags from stainless steel production. This and similar research seems to indicate that carbonation is not just a chemical reaction but considering the necessary conditions for carbonation (dissolution in water, accessibility of carbon dioxide, …) can be seen as a binding process. The outcome of such carbonation processes in historical materials and construction as well as in nature (geology) helps to estimate the durability of materials generated through a carbonation process. This throws an insight on the relation between carbonation and durability which is very different from the perspective the world of concrete has on the phenomenon and it also may lead research towards materials that are durable and help reduce the carbon dioxide content in the air, which also contributes to sustainability.status: publishe