Lime mortars are more porous and soft compared
to other cement-based systems 19 and can be effectively used as a potential candidate
to repair and rehabilitate heritage structures. The sizes of the pores present
in lime mortar materials used in the current study are widely vary from
>10?m to < 1?m. The shape of the pores, orientation and interconnections with adjoining pores also widely varied. The most pores are isolated and Some are interconnected. This may be resulted in widely varied permeability of lime mortars.   The sizes of larger pores vary between 200×50?m and 250×100?m with length and breadth ratio varying between 4 and 2.5. The linear pores are found along inter-granular boundaries with length and breadth ratio varies between 5 and 4. The smaller pores less than 10?m are well rounded. The well-developed globular grains amidst the matrix of saccharoidal carbonate materials are seen in the crystal form of druses with large volumes of cavities around these crystals. The matrix is enriched with needles of fibrous carbonate materials (20×0.5?m); are seen as bundles of radiating aggregates (10?m from the centre to 20?m in peripheral portions) in some samples. The nature and form of these minerals indicate that they are composed with significant amount of water, hydroxides or other anionic components. The chloride crystals are rapidly developed by the process of evaporation of droplets from their peripheral portions by leaving hallow spaces at their centre. These hopper or skeletal crystals of sodium chloride enriched halite were started crystallization initially at the peripheral portions; indicating that they were rapidly crystallized by evaporation process leaving a hollow space at the centre. The sizes of hollow spaces present at the centre of these crystals vary from 0.1×0.1?m to 2×1?m. The peripheral rims of halite vary between 0.2 to 0.5?m. The sizes of halite crystals vary between 1.5×1.0?m and 0.5?m. A linear chain of such halite crystals indicate that they were crystallized along a linear crack of 5×2?m; tapering at both ends and appear to be a flake like fracture at interstitial spaces of the matrix of carbonate minerals of host; by capillary influx of pore fluid and subsequent evaporation. However, the matrix and co-existing minerals are characteristically of non-chlorides and are carbonates. A larger cavity of 4×3?m size is completely filled with numerous skeletal crystals of halite with cavities at their centre as aggregates. The successive individual layers of halite are also seen in this cavity. Some globular beads of halite are also seen within the cavity. The size of halite also varies from 0.2?m cubes to prisms of 4?m ×0.75?m with length and breadth ratio exceeding over 5 indicating its rapid free growth in a cavernous environment.  Generally capillary forces are effective between the pore sizes of 1 and 10?m 19. The EDS analyses showed that the matrix was essentially composed of carbonate materials.