Mortar
Highbridge staff are recognized experts in the materials and technology of both historical and modern masonry. We specialize in compositional analysis through petrography and chemical analysis, and physical property evaluations of fresh and hardened mortars and grouts.
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Compositional Analysis
Petrography and chemical analysis are standard tools used by our materials scientists to determine the proportional composition of existing masonry mortars. As preservation scientists, we are also industry leaders in the development of novel methods for the characterization of historical cements, limes, and mortars. We have assisted on over a thousand historic preservation projects with experience ranging from prehistoric archaeological studies to twentieth century Art Deco.
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Permeability Studies
The concept of compatibility between masonry units and mortar is really about verifying that the physical properties of the wall components will provide the desired performance. Differences in liquid-water capillarity and water-vapor permeance inform the pathways of moisture movement in a masonry assembly. Understanding these differences can help explain patterns of past deterioration or help design successful repair mortars.
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Provenance Evaluations
Our scientists have spent years researching the history of cements and limes, visiting original mines and quarries, and recreating binders in the laboratory from historical sources. We have studied the microtexture and chemical fingerprints of well-documented specimens, and have developed diagnostics that allow us to constrain manufacturing dates and geographic provenance. With these tools we can provide critical context to historical site surveys, or assist in establishing construction sequences at complex architectural sites.
Test Methods for Mortar
Highbridge performs many tests in accordance with standard test methods but also constructs protocols for property characterization and durability evaluations using proprietary methods.
Mortar Test Methods:
Some test standards published for other materials are adapted for historical mortars or their repair mixtures.
ASTM C109 Standard Test Method for Compressive Strength of Hydraulic Cement Mortars
ASTM C1152 Standard Test Method for Acid-Soluble Chloride in Mortar and Concrete
ASTM C1218 Standard Test Method for Water-Soluble Chloride in Mortar and Concrete
ASTM C1324 Standard Test Method for Examination and Analysis of Hardened Masonry Mortar
ASTM C1437 Standard Test Method for Flow of Hydraulic Cement Mortar
ASTM C1498 Standard Test Method for Hygroscopic Sorption Isotherms of Building Materials (reference water content)
ASTM C1794 Standard Test Methods for Determination of the Water Absorption Coefficient by Partial Immersion
ASTM C1922 Standard Test Method for Water Retention of Hydraulic Cement-Based Mortars and Plasters by Way of Water Loss
ASTM E96 Standard Test Methods for Water Vapor Transmission of Materials
ISO 12572 Hygrothermal performance of building materials and products — Determination of water vapour transmission properties — Cup method
DIN EN 12087 Determination of long term water absorption by immersion (free water saturation)
Proprietary Instrumental Analysis:
Highbridge partners with trusted institutions and commercial providers to offer research-grade instrumental analysis.
X-Ray diffraction analysis of water-soluble salts extracted from masonry
Scanning electron microscopy and energy-dispersive x-ray spectroscopy
Thermogravimetric analysis for identification or quantification of volatile constituents
Fourier transform infrared spectroscopy of organic constituents
Pyrolysis - Gas chromatography / mass spectroscopy for organic components
Transient plane source for thermal conductivity and heat capacity
Mortar Specifications:
ASTM C270 Standard Specification for Mortar for Unit Masonry
ASTM C1713 Standard Specification for Mortars for the repair of Historic Masonry