Building Materials Classification

Classification of Building Materials

• Building materials can be classified into two categories:
  • Structural materials: used to resist loads, such as reinforced concrete and steel
  • Nonstructural materials: not designed to carry loads, such as brick or wood partitions

Physical Properties of Building Materials

• Density (ρ): mass per unit volume of a material
  • Calculated by: ρ = M / V
  • Unit: g/cm3
• Apparent Density (ρ0): dry mass per unit volume of a substance under natural conditions
  • Calculated by: ρ0 = M / V°
  • Unit: Kg/m3
• Bulk Density (ρb): dry mass per unit volume of a substance under packing conditions
  • Calculated by: ρb = M / Vb
  • Unit: Kg/m3
• Unit Weight (𝛾): weight per unit volume of a material
  • Calculated by: 𝛾 = W / V or 𝛾 = ρ°g
  • Unit: N/m3
• Specific Gravity (Gs): ratio of the density of a solid material to the density of distilled water
  • Calculated by: Gs = ρs / ρw or Gs = γs / γw
• Porosity (η): percentage of the pores volume to the total volume
  • Calculated by: η = Vv / V
• Voids Ratio (e): ratio of the volumes of voids to the volume of solid material
  • Calculated by: e = Vv / Vs
• Moisture Content (m): percentage ratio of the weight of water in the voids to the weight of solid material
  • Calculated by: m% = (Mw / Ms) × 100%
• Degree of Saturation (s): percentage ratio of the volumes of water in the voids to the total volume of voids
  • Calculated by: s% = (Vw / Vv) × 100%
• Water Absorption: ability of the material to absorb and retain water
  • Calculated by: Ww% = ((Ms - Md) / Md) × 100%

Mechanical Properties of Materials

• Mechanical behavior: response of the material to external loads
• Elongation (e%): largest amount of elongation at failure or the ratio between the amount of elongation and original length
  • Calculated by: e% = (ΔL / L) × 100%
• Longitudinal Strain (εL): calculated by dividing the total deformation of the dimension parallel to the direction of applied force by the original dimension
  • Calculated by: εL = ΔL / Lo
• Lateral Strain (εa): calculated by dividing the total deformation of the dimension vertical to the direction of applied force by the original dimension
  • Calculated by: εa = ΔY / Yo
• Poisson's Ratio (V): ratio of lateral strain to the longitudinal strain
  • Calculated by: V = εa / εL
• Linearity: stress-strain relation follows a straight line
• Elasticity: material returns to its original shape when the load is removed and reacts instantaneously to changes in load
• Elasto-plastic materials: exhibit linear elastic behavior followed by plastic response
• Stress-strain curve: graphical representation of the stress and strain relationship

Fire Resistance, Chemical Resistance, and Durability

• Fire Resistance: ability of a material to resist the action of high temperature without deformation and loss of strength
• Chemical Resistance: ability of a material to withstand the action of acids, alkalis, seawater, and gases
• Durability: ability of a material to resist the combined effects of atmospheric and other factors

Hardness and Abrasive Resistance

• Hardness: property of a material to resist pressing-in or scratch of a sharp object
• Abrasive Resistance: capacity of a material to resist abrasion
  • Calculated by: N = (m1 - m2) / A
  • Unit: gm/cm2