Air lime–metakaolin–sepiolite mortars for earth based walls

Highlight
• Metakaolin and sepiolite were chosen as additives for lime mortars.
• Mortars were studied as prisms, applied on adobes and adobe wall.
• Optimal behaviour has mortar containing both, metakaolin and sepiolite.

The present study aims to evaluate the behaviour of mortars based on lime, with the addition of metakaolin and sepiolite, seeking their application as renders on adobe walls. Since the renders used in traditional adobe buildings are mortars whose binder is lime, three mortars were formulated based on lime. An air lime mortar with sand and two other mortars, also based on air lime, but with the addition of metakaolin or metakaolin and sepiolite were tested. The mortar prisms 4 × 4 × 16 cm were analysed in the laboratory conditions in view of mechanical properties. In parallel, the mortars were placed on old adobes, taken from demolished houses and their behaviour was verified with artificial accelerated ageing tests. Finally, mortars were placed on a wall made from traditional adobes, where panels were monitored and trials with Karsten tubes and Schmidt hammer have been conducted. The results obtained by comparison of the characteristics of mortars studied as prisms in laboratory conditions, applied on adobes and the adobe wall provided an extended study which is necessary to assess the suitability of mortars for use in the rehabilitation of adobe buildings.