• Granite masonry Rosendale cement pointing at the Brooklyn Bridge, New York
  • Chemist performing analysis at ICP-OES to determine chemical composition of historical mortar
  • Thin section image of nineteenth century lime plaster with lime washes and gypsum plaster repair
  • Chemist digesting historic mortar samples for compositional analysis using ASTM C1324
  • Sand and pigment extracted from a red lime mortar using acid digestion

Historical Mortar Analysis

Our staff possesses an unrivaled knowledge of North American binders and masonry mortars. Our analysis includes petrographic and chemical methods to evaluate historical mortar compositions.

Preparing a petrographic grain mount of an insoluble residue after chemical analysis
 

Historical mortar analysis is often a part of many preservation projects and repointing efforts.  Our clients use the information provided by this testing to design appropriate repairs and for documentation purposes.  Highbridge provides a compositional analysis that includes a combination of microscopy techniques (petrography) and chemical analysis.

Goals of Historical Mortar Analysis

  • Estimate original mix designs to guide repair strategies

  • Satisfy requirements for historic tax credits

  • Document unique materials and construction sequences for historic structures reports

  • Assess consistency in workmanship and understand general performance qualities

  • Evaluate distress that may impact the success of planned repairs (e.g., moisture infiltration, salt deposition, freeze-thaw cracking)

Our experience with historical binders comes from diligent archival research and from field studies at original quarry sites.  We have examined thousands of historical mortars from every time period and geographical region in the United States, Canada, and the Caribbean.  Our on-site mortar collection is the largest and most comprehensive in the world.

Our mortar analyses are based on ASTM C1324.  As pioneers in the field, we have modified these methods to more accurately characterize the wide variety of historical mixes.  Through presentations, publications, and university teaching, we continue to share our knowledge with the industry and its emerging professionals.  Our staff hold faculty positions at Columbia University's graduate program in historic preservation and are active members of the Association for Preservation Technology and ASTM International.