Characterization of lime plasters used in 16th century Mughal monument

This paper addresses the results of mineralogical and physico-chemical investigation of 16th century Mughal plaster of Bibi Ka Maqbara, the Taj of Deccan. The study investigated micro-morphological structure of various components of the plaster for the great to provide a basis for future restoration. The investigation on particle size distribution of aggregates in the plaster was carried and the result correlated to the strength of the plaster. Sieve/petrological analysis indicate the addition of creamy white zeolites (also detected by Raman spectrum) along with crushed amygdaloidal basalt of different grain sizes as aggregate in the plaster. The component material of the plaster and its purity has been studied through thermal analysis. The outer plaster layer was characterized for addition of hygroscopic organic additive with active carbonyl group by FTIR spectroscopy. The SEM images show salt crystallization in the pores as one of the reason for failure of plaster at some location, probably due to recent conservation with cement mortars/plaster of paris.