Conservation & Restoration of Lime Mortars & Brickworks: CSIR-CBRI

A study on conservation and restoration of lime mortars & brickworks carried out by Environment Science & Technology Group at CSIR-Central Building Research Institute (CSIR-CBRI), Roorkee, has investigated the composition of historical mortar/plaster types, their current condition, factors and processes responsible for their deterioration. Based on the characterisation of mortar and plaster types, an intervention technique is formulated.

  • Lime has been used as the binding material for the preparation of all three building mortar samples.
  • The higher firing temperature clay minerals are absent in B1 and B2 bricks which confirms that bricks are fired at moderate temperature i.e. ~ 870°C.
  • The presence of calcite in the mortar matrix was also confirmed and can be seen as layered form as confirmed in FE-SEM analysis.
  • The presence of protein in mortar (M1-M4) samples is confirmed by the characteristic peak of amide and CO groups. Further qualitative tests were also performed for confirmation.
  • In mortar sample lime, surkhi, brick aggregates along with wheat straw fibres were also present in M3 samples.
  • The presence of lime is confirmed by XRF and XRD analysis.
  • Based on XRD results, it can be inferred that B3 bricks were manufactured by firing 850 900°C. 
  • The result shows that the main mineralogical phases in M5 mortar samples are Quartz (Q) and Calcite (C) while Anorthite (A) is present as a minor phase.
  • XRF analysis of bricks indicates a high content of silica 59% and Al2O3 26% along with 2-4% traces of other elements.
  • XRD analysis shows the peaks of Quartz (Q:SiO2) Tridymite (T), Cristoballite (Cb), calcium silicate complex and fired at between 950-1000°C.
  • Technology for the preparation of nanolime for heritage building conservation has been transferred to M/s Poysha Nanotech LLP., Haridwar.
  • A pilot plant for the preparation of nano-lime has been developed at CSIR-CBRI.

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