Chemical and mineralogical characterization of old mortars from jahangir tomb, Lahore-Pakistan

Abstract

The 17th century tomb of the Mughal Emperor Jahangir has suffered several conservation and restoration interventions throughout its existence, without any systematic previous knowledge of the chemistry and mineralogy of old mortars. The characterization involved a multidisciplinary set of chemical, physical and micro-structural techniques, particularly X-ray fluorescence spectrometry and scanning electron microscopy equipped with EDS detector to determine the chemical composition of the mortars, which provides necessary information for compatible mortars as well as the state of conservation. The XRD and petrographic studies results show that the mortars were a variable mixture of burnt lime and fine Ravi river sand. The binder being the calcitic lime was obtained from kankar (lime nodules) abundantly found in zone B of Lahore soils and in its surrounding area which contains 70 % CaCO3, 30 % clay and a fraction of sand with other impurities. The aggregates used were sand, brick pieces and broken kankar. Surkhi (pulverized brick) and rarely slag were used as pozzolanic materials to increase the strength of the mortars.