Performance Evaluation of Lime Mortars with Metakaolin and CMC for Restoration Application

The degradation of ancient buildings has attracted much attention, and plane lime mortar cannot meet the requirements of utilization in special environmental loads or buildings. In order to improve the hydraulic properties and freeze-thaw resistance of lime mortars, both carboxymethyl cellulose (CMC) and metakaolin were added to plane lime mortars in this study. The performance of lime mortars with different additives was evaluated. The experimental results showed that the combined effect of CMC and metakaolin on compressive strength of lime mortars could be divided into three stages according to the curing age. The early compressive strength of blended mortars is improved. With increasing curing ages, the compressive strength varied in accordance with the phase transition of hydration and carbonation products. Furthermore, blended mortar with a long curing age exhibits better freeze-thaw resistance. These results suggest that the combined action of metakaolin and CMC played a significant role in the properties of lime mortars, which is generally beneficial for restoration applications, especially for ancient buildings in cold regions.