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Masonry
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Masonry

Structural masonry is an assembly of masonry units of bricks or concrete or stone blocks, bonded together with mortar, used in buildings and civil engineering structures. Like concrete, masonry is good in compression but brittle and weak in tension. Hence, their use is restricted to use in situations where they largely remain in compression. An exception is when large wall panels are subject to horizontal wind loads, which produce bending and small tensile stress to the masonry.

It is noteworthy to distinguish between bricks and brickwork. Bricks are the individual units whereas brickwork refers to the complete product including the mortar. The compressive strength of brickwork is significantly less than that of the individual bricks.

Table 1 summaries the common types of masonry units and mortars. It is noteworthy that the
natural stone units are excluded in here.

Table 1: Types of Masonry Unit and Mortar
Material Type
Masonry Clay, calcium silicate,
concrete
, autoclaved aerated concrete (AAC),
lightweight concrete aggregate
Mortar General purpose mortar, thin layer mortar, lightweight mortar

Fire resistance of masonry constructions is always measured on structural elements, such as block or brickwork walls and columns, and there are no requirements for individual units or the bonding mortar. Historically, masonry walls have demonstrated excellent fire resistance, provided that the foundations and supporting structure can keep the wall in place during the fire. However, thermal bowing of very tall unreinforced cantilever masonry walls due to a severe fire on one side of the wall can lead to collapse (Buchanan 2001).

British codes currently do not give a calculation method for masonry, and design is on the basis of experimentally determined resistance levels for walls (Vekey 2002). Guideline on fire resistance is stated as the minimum thickness of masonry walls of various types of construction to give a stated fire resistance period ranging from 30 minutes up to 6 hours.

In general, for a given material type, fire resistance increases with:

  • Thickness
  • Thermal resistance of the body material
  • Absorbed or combined water content
  • Any non-combustible applied finishes, especially insulating plasters and renders

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