Despotou E.; Schlegel T. (2016) Literature study on the rate and mechanism of carbonation of lime in mortars

ABSTRACT

The hardening kinetics of a lime based mortar is based on the up take of carbon dioxide from the ambient air; The presence of watervapour is required in order to enable the reaction between the CO2 and the lime (calcium hydroxide). Via this reaction the hardening of air lime is net uptaker of CO2.

An extensive literature study was made on the fundamentals of the carbonation process in mortars with different compositions. The results of the study indicate that carbonation ranges from 80 % up to 90 %. It/s clear that the mechanism and the kinetics of the carbonation depend strongly on the mineralogy, texture of mortars, type of additive used, the lime use for the mortar, the width of the walls, thickness of the mortar (less carbonation when mortar depth increases) as well as the time frame allowing for the carbonation process to take place.

Under natural conditions, actual building practice and depending on the thickness of the mortar/p/aster; carbonation takes between a few weeks and several years. The results of this study were used for the environmental footprint study in order to calculate the capture of CO2 that occurs progressively during the hardening of a building materials containing lime.