Thermal analyses (TGA, DTG, DTA, and DSC) of construction materials are useful for detection of various hydrous, carbonate, and sulfate phases from their characteristic decomposition temperatures and associated weight changes (as detected in TGA and DTG) or differential temperature change (in DTA) or change in heat flow (detected in DSC), such as:


  • 120-150°C = Ettringite decomposition from cement paste (thaumasite at 150ºC) and water release (endotherm)

  • 120, 180-200°C = Gypsum decomposition and water release (endotherm)

  • 100-200ºC = Hydrate water from decomposition of calcium silicate hydrate (CSH)

  • 300-400°C = Brucite decomposition from dolomitic lime mortar (or from soluble magnesium salts in the paste from the use of natural cement) and water release (endotherm)

  • 400-600°C = Portlandite decomposition from Portland cement paste and water release (endotherm)

  • 500-680°C = Magnesite decomposition for dolomitic lime mortar (endotherm)

  • 573°C = Alpha-to-beta polymorphic transformation of quartz the main component of silica sand in mortar

  • 620-690°C = Calcite decomposition for cryptocrystalline calcite formed during carbonation of lime in mortar

  • 680-800°C= Calcite decomposition for coarsely crystalline calcite in limestone or marine shells (endotherm)

  • 740-800ºC = Dolomite decomposition (endotherm)

  • >950°C = Slight exotherm from initial surface reaction of lime and silica, followed by larger endotherm from melting.

CMC has a Mettler-Toledo TGA/DSC1 thermal analysis unit that can analyze up to 34 samples simultaneously to determine various hydrous, sulfate, and carbonate phases in construction materials.

 

METTLER TOLEDO'S ONLINE TUTORIALS ON THERMAL ANALYSIS AND SOFTWARE

 

METTLER TOLEDO'S BROCHURES ON TGA/DSC1 AND STAR SOFTWARE

 
 
 

HOW WE DO THERMAL ANALYSIS

 
 
 
 
 
 
 
 
 
 
 

SOME RELEVANT PUBLICATIONS ON APPLICATIONS OF THERMAL ANALYSIS IN CONSTRUCTION MATERIALS

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