Types of Masonry Construction, Characteristics And Common Uses
Virtually, all buildings incorporate some type of masonry construction, whether it is a stone or concrete foundation, brick veneer walls, or terra cotta ornamentation. Preservation of these buildings requires a basic understanding of masonry types and their characteristics, technology and construction methodology, proper maintenance and conservation treatments.
Masonry is generally a highly durable form of construction. However, the quality of material used, together with the quality of the mortar and workmanship can strongly affect the durability of the overall masonry construction. Masonry is commonly used for the walls of buildings, retaining walls and monuments. Brick is the most common type of masonry and may be either load bearing or a veneer. Concrete Masonry Units (CMU’s) are made from concrete and are larger than ordinary bricks. CMU walls can be reinforced by filling the block voids with concrete and steel reinforcing bars. Typically, not all voids are filled, but rather those at corners, wall ends, adjacent to window and door openings, which increase wall strength and stability. Placement of steel reinforcement generally results in a CMU walls having much greater lateral and tensile strength than unreinforced walls.
The earliest material to be used was stone. It can be obtained in two ways: from natural outcroppings or scattered deposits, and by the process of quarrying. Most early buildings were constructed of stone readily available near the building site. Early stonemasons also were aware that certain stone types had more -weatherability- – able to withstand the effects of weather better than others – and they utilized each type in accordance with its properties. Stones may be laid up in their natural form, or broken and squared, or shaped, for the proper fit with other stones in the wall.
Quarrying, the industrial process of extracting stone from the earth requires substantial effort and technology. In this process, stone is drilled, blasted, fractured or cut from the quarry face, and then shaped and finished for use in construction.
Concrete masonry units (block and concrete brick are available in sizes, shapes, colors, textures, and profiles for practically every conceivable need and convenience in masonry construction. In addition, concrete masonry units may be used to create attractive patterns and designs to produce an almost unlimited range of architectural treatments of wall surfaces. The following are some more prominent uses:
Exterior load-bearing walls (below and above grade)
Interior load-bearing or non load bearing walls
Fire walls, party walls, curtain walls
Partitions, panel walls, solar screens
Backing for brick, stone, stucco, and other exterior facings
Veneer or nonstructural facing for wood, concrete, or masonry
Fire protection of structural steel members
Firesafe enclosures of stairwells, elevator shafts, storage vaults, or fire hazardous work areas
Piers, pilasters, columns
Bond beams, lintels, sills
Floor and roof systems
Retaining walls, slope protection, ornamental garden walls, and highway sound barriers
Chimneys and fireplaces
Catch basins, manholes, valve vaults
Paving and turf block
Solid brick masonry is made of two or more layers with the units running horizontally (called -stretcher- bricks) bound together with bricks running transverse to the wall (called -header- bricks). Each row of bricks is known as a course. The pattern of headers and stretchers employed gives to different bonds such as the common bond, with every sixth course composed of headers, the English bond, and the Flemish bond, with alternating stretcher and header bricks present on every course. There are no real significant utilitarian differences between most bonds, but the appearance of the finished walls is affected. Brickwork, like unreinforced concrete, has little tensile strength, and works by everything being kept in compression.
There are many brick laying patterns, the following are but a few:
Stack Bond The brick laying patterns described by this term are not structurally sound and are used only for decorative purposes. The stack bond is a run of stretchers with each stretcher stacked centered on the stretcher below it. All joints run vertically down the entire wall.
Running Bond brick laying patterns are a run of stretchers with each stretcher placed in the center of the stretcher below it. This pattern gives a reasonable amount of structural soundness.
English Bond is made up of alternating courses of stretchers and headers. This is the strongest bond for a one-brick thick wall.
Bat is a brick cut in half or quarter along the short face
Closer A queen closer is brick cut in half down the long face. They are used in corners of English or Flemish Bond.
Header Brick is laid in a wall, usually connecting two rows of a double wythe wall. The smallest end of the brick is horizontal, aligned with the surface of the wall and exposed to the weather.
Quoins are groups of brick that project slightly from the face of a wall at the corner of a building. The pattern often alternates with several courses projecting bricks, and several courses that are aligned with the wall. The pattern of projecting quoins often alternates with the brickwork on the other side of the corner.
Rowlock is a complete course of brick laid on its side, with the shortest end of the brick exposed and vertical. Commonly used on the top course as a coping for a garden wall.
Sailor Brick are laid on its end with the largest, broad face exposed.
Shiner Brick laid on edge like a sailor, but the broad face is set horizontally.
Soldier Brick often is a complete course of brick laid on end vertically, with the narrow side exposed in the face of the wall.
Wythe is a single vertical wall of brick.
Clay Brick vs. Concrete
The formula for brick making has not changed for hundreds of years. The primary ingredients are clays and shale. It is these ingredients that give natural brick its colors and hue.
The natural color of concrete is gray. In order to give concrete bricks color, additives are necessary to create the variety of colors. Weather and the ultraviolet rays of the sun can cause concrete bricks to fade over time.
Concrete bricks have a tendency to shrink. During the concrete curing process, if the bricks are not properly cured prior to being delivered to the jobsite, shrinking and cracking will appear at the mortar joints and can allow water to enter the wall cavity.
According to a recent survey of architects, designers, engineers, and environmental planners and managers conducted by the Portland Cement Association (PCA), 77 percent chose concrete as a sustainable material. Overall, respondents ranked concrete favorably for its energy efficiency, durability and reduced maintenance. Over 500 individuals participated in the blind survey presented in an Internet survey form by a third party web host.
According to PCA President, -buildings with exterior concrete walls utilize less energy to heat and cool than similarly insulated buildings with wood or steel frame walls-. Additionally, -the superior insulation, air tightness, and mass of the walls can reduce energy for heating and cooling by up to 40%.