Abstract
An investigation of characteristics of materials and techniques used for the repair of Kala Burj, Lahore Fort, Lahore was carried out. Through experience, it was established that the conservation through repair work carried out on the significant building should be identical to the authentic original techniques and materials as accurate as possible. Objective behind it is to make connection with the past and to age in the same manner as the original material. This helps to add life to the historical structures. Hence, different methods were applied to investigate the materials originally used in the construction of this monumental building of Kala Burj like, the instrumental and non-invasive techniques. Investigation of mortar samples of Kala Burj displayed that mortar was a flexible blend of fine Ravi Sand and burnt lime. The ratio of constituents of kankar lime in the vicinity of Lahore city was found to be calcium carbonate (CaCO3)?70% and 30% clay and sand along with some impurities. Nature has provided this material certain impurities to achieve the required bonding strength. Nearby soil was used to produce burnt lime from kankar. Anthropogenic and natural sources of fluorides, SO3, CO2,?NO3, and dust produced through the bustling traffic across the road were the major factors causing deterioration of the materials of the Kala Burj. Finally, after thorough analysis, the mortar with appropriate ratio comprising of sand, fine kankar and coarse kankar was recommended. The ratio suggested through analysis was 1.0: 1.0: 1.1 to 2.7.