IfcRelAssociatesMaterial is an objectified relationship between a material definition and elements or element types to which this material definition applies. 

The material definition can be:

• Assigned to an element occurrence as a specific usage of a layer set or profile set
• Assigned to an element occurrence or element type as a layer set, profile set, constituent set or a single material

Materials can be arranged by layers and applied to layered elements. Typical elements are walls and slabs.

• An IfcMaterialLayerSet, for layered elements with an indication of the layering direction and individual layer thicknesses
• An IfcMaterialLayerSetUsage, i.e. a material layer set with positioning information along the reference axis or surface of the element. NOTE: As a material layer set usage is an occurrence based information, that applies to each individual element, it cannot be assigned to an element type.

Material can be applied to profiles. Typical elements using profile material are beam, column, member

• An IfcMaterialProfileSet, i.e. a set of material assigned to a set of profiles, with a single material assigned to a single profile as the default.
• An IfcMaterialProfileSetUsage, i.e. a material profile set with positioning information relative to the element axis, also referred to as cardinal point. NOTE: As a material profile set usage is an occurrence based information, that applies to each individual element, it cannot be assigned to an element type.

Materials can be arranged by identified parts of a component based element. Typical elements are doors/windows (with components such as lining, framing and glazing), or distribution elements. 

The IfcRelAssociatesMaterial relationship is a special type of the IfcRelAssociates relationship. It can be applied to subtypes of IfcElement and subtypes of IfcElementType.

• The IfcElement has an inverse relation to its material definition by the HasAssociations attribute, inherited from IfcObject.
• The IfcElementType has an inverse relation to its material definition by the HasAssociations attribute, inherited from IfcPropertyDefinition.

• As a material layer set usage is an occurrence based information, that applies to each individual element, it cannot be assigned to an element type.
• As a material profile set usage is an occurrence based information, that applies to each individual element, it cannot be assigned to an element type.