CaSO4·2H2O + paper faces
ChemistryGypsum board is specified as CaSO4·2H2O + paper faces. Density band ~700–1000 kg/m³.
What holds Gypsum board together is not the nickname. Formula CaSO4·2H2O + paper faces, density ~700–1000 kg/m³.
Meters are atlas-relative. Grades are the SKUs buyers write.
Phases
Microstructure
OrderProcessing sets grain, crystallinity or fibre orientation — the reason two lots of Gypsum board can test differently.
Interfaces
SurfacesCoatings, oxide films, sizings or paper faces often decide weather and fire behaviour more than the bulk brochure.
Defects
FlawsInclusions, voids, knots, pinholes or residual stress start the failures that mill certificates do not list.
Grades
VariantsGypsum board is a family. Grade names below are the ones buyers actually write on RFQs.
Ageing
TimeMoisture, UV, creep, hydrogen or carbonation shift properties in service. Design to the aged state.
Relative meters
Strength24
Strength is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Heat envelope54
Heat envelope is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Fire behaviour92
Fire behaviour is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Insulation34
Insulation is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Workability90
Workability is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Circularity62
Circularity is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Grades
Standard 12.5 mm
Interior partitions.Interior partitions.
Type X / F
Fire assemblies.Fire assemblies.
MR / H2
Bathrooms, still not tile backer forever.Bathrooms, still not tile backer forever.
Shaftliner
2-hour shafts.2-hour shafts.
Acoustic laminated
Constrained layer.Constrained layer.
Bonds
Primary bonding
Gypsum board holds together by ionic/covalent networks.
Secondary forces
Hydrogen bonds, van der Waals stacks or grain-boundary cohesion set toughness and moisture uptake.
Composites & fills
Fillers, fibres, plasticisers or aggregates are part of the real product, not impurities.
Environment film
Oxides, chars, sizings or paints are the layer the world actually meets.
Change the grade, the coating or the moisture and you have a different material with the same English name.
Keep exploring
More in Fire performance
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Overall 62