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MASONRY. What is Masonry?. - is an assembly of bricks, blocks or stone held together with mortar. The common materials of masonry construction are :- Brick Stone (marble, granite, limestone, concrete block) Concrete Block
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What is Masonry? • - is an assembly of bricks, blocks or stone held together with mortar. • The common materials of masonry construction are :- • Brick • Stone (marble, granite, limestone, concrete block) • Concrete Block • - is commonly used for the walls of buildings, retaining walls and monuments.
Generally masonry walls consists of rectangular units built up in horizontal layers called courses. A mason laying mortar on top of a finished course of block, prior to placing the next course.
Functions of Masonry • Carry loads of ceilings/roof/ upper floors. • Divide and define internal spaces. • Prevent vegetation/vermin entering interior. • Control/provide openings – access/lights/ventilation
STONE MASONRY The craft of stonemasonry has existed since the dawn of civilization - creating buildings, structures, and sculpture using stone from the earth. These materials have been used to construct many of the long-lasting, ancient monuments, artifacts and cities in a wide variety of cultures. Famous products of stonemasonry include the Taj Mahal, the Egyptian Pyramids and Stonehenge.
Stone Masonry: Building stones obtained by quarrying from the rocky strata of earth and reducing it to the required shapes and sizes for construction. Types of rock: 1. Igneous- Formed as a result of cooling of the molten rock to solid state - It is nonporous, hard, strong and durable • - Granite: Consists mainly of quartz, feldspar, mica, and other colored minerals; colors include black, gray, red, pink, brown, buff, and green. • - Basalt: Color ranges from gray to black; used mainly for paving stones and retaining walls
2. Sedimentary: Sediments deposited by the action of water or wind gets consolidated to a rock. • - Sandstone: Sedimentary rock composed of sand sized grains made of silica, iron oxide and clay - Colors include gray, brown, light brown, buff, russet, red, copper, and purple • - Shale: Derived from clays and silts; weak along planes and is in thin laminations - High in limestone and color varies from black to red, yellow, and blue. • - Limestone:Sedimentary rock composed of calcite and dolomite - Three types: oolitic, dolomitic and crystalline - Has high compressive strength - Used for building stones and for paneling
3. Metamorphic: Igneous or sedimentary rock transformed by heat and pressure into another rock • - Marble: Recrystalized limestone, color varies from white through gray and black, red, violet, pink, yellow, and green - Presence of oxides of iron, silica, graphite, carbonaceous, matter, and mica produce these color variations • - Quartzite: It is a variety of and stone composed of mainly granular quartz cemented by silica, color varies from brown, buff, tan, ivory, red through gray • - - Slate: Consists mainly of clays and shale - Major ingredients are silicon dioxide, iron oxide, potassium oxide, magnesium oxide, and sometimes titanium, calcium and sulfur - Slate found in parallel layers, which enables it to be cut into thin sheets
Metamorphic Rock Slate Marble
QUARRYING AND PRODUCING BUILDING STONES • Produced by blasting or cutting • Irregular-sized stone is produced by blasting the rock, the larger pieces are cut into smaller units for use as an exterior finish, the rest is crushed and sorted into various sizes as aggregates • Most of the dimensional stones used in building construction are produced by cutting large blocks in the quarry • - Cut with diamond belt saws (12ft wide, 2 to 5 ft thick, and 50 ft long); rubber air bags inflated in the saw cut to break it away and then the separated rock is lowered onto prepared stone chips cushion • - Thereafter it is cut into smaller sizes and transported by front-end loaders to the mill for further processing
Laying of stone masonry blocks in a wall: (a) Rubble Masonry - Composed of un-square pieces of stones; mason has to choose carefully each stone so that it can fit into the available space (b) Ashlar masonry - Made of squared pieces of stones; mason has to carefully lift the heavy stones by a hoist and lower it into place (c) Coursed stone masonry: has continuous horizontal joints (d) Uncoursed or random masonry : Does not have defined bedding planes for the wall
Stone Masonry Patterns • Rubble (Unsquare pieces) • Ashlar (Square Pieces) • Coursed or Random
Concrete masonry unit (CMU) The standard concrete block is a rectangular 8X8X16-inch unit (200X200X400 mm) made mainly of portland cement, gravel, sand, and water. Concrete masonry is widely used to construct small and large structures. The most common application of concrete masonry is walls for buildings. CONCRETE BLOCKWORK
Bond Beam Typical Shape Combination ‘Corner’ – Round & Square
Types of bricks: 1.Building bricks 2.Pressed brick 3.Glazed brick 4.Fire brick 5.Sand-lime brick
1.Building bricks: • Building brick, also called common, hard, or kiln-run brick, is made from ordinary clay or shale and is fired in kilns. • These bricks have no special shoring, markings, surface texture, or color. • They are generally used as the backing courses in either solid or cavity brick walls, the harder and more durable types are preferred.
2.Pressed brick: • The dry press method is similar to mud brick but starts with a much thicker clay mix, so it forms more accurate, sharper-edged bricks. • The greater force in pressing and the longer burn make this method more expensive. • Bricks which, before burning, have been subjected to pressure, to free them from the imperfections of shape and texture which are common in molded bricks are called pressed bricks.
3.Glazed brick: • The internal faces of walls, lavatories, and bathrooms to be faced with first quality white glazed bricks as described, laid in Flemish bond in cement mortar with fine joints. • Glazed Brick are extruded clay masonry units for building veneers and partitions.
4.Fire brick: • A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnace, kilns, fireboxes, and fireplaces. • A refractory bricks is built primarily to withstand high heat, but should also usually have a low thermal conductivity to save energy.
7.Sand-lime brick • Decorative brick made of sand and lime pressed in an atmosphere of steam. These bricks have the following advantages over the clay brick: 1. Possess adequate crushing strength as a load bearing member. 2. Have cement color in appearance, are uniform in shape and smooth in finish, require no plastering for building work and consume less mortar. 3. Are lighter in weight than ordinary clay bricks. 4. They can be produced in colors if desired
Properties of bricks: • Bricks should have uniform size and plane, rectangular surfaces with parallel sides and sharp straight edges. • The brick should have uniform texture. It should be free from fissures, holes, grits or lumps of lime. • Water absorption should not exceed 20% of its dry weight when kept immersed in water for 24 hours. • Crushing strength should not be less than 10.5N/mm2 • Bricks should be well burnt for use in construction purposes.
The important properties of brick are: 1) texture 2) compressive strength and 3) absorption
Texture: Many brick have smooth or sand-finished textures produced by the dies or molds used in forming. A smooth texture, commonly referred to as a die skin results from pressure exerted by the steel die as the clay passes through it in the extrusion process.
Compressive Strength and Absorption Both compressive strength and absorption are affected by properties of the clay, method of manufacture and degree of firing. For a given clay and method of manufacture, higher compressive strength values and lower absorption values are associated with higher firing temperatures. Although absorption and compressive strength can be controlled by manufacturing and firing methods, these properties depend largely upon the properties of the raw materials.
Phases of Manufacturing The manufacturing process has six general phases: • Mining and storage of raw materials, • Preparing raw materials, • Forming the brick, • Drying • Firing and cooling and • De-hacking and storing finished products
1. Mining and Storage: • Surface clays, shales and some fire clays are mined in open pits with power equipment. • Then the clay or shale mixtures are transported to plant storage areas. • Continuous brick production is ensured by storing sufficient quantities of raw materials required for many days of plant operation.
Photo 1 Clay or Shale Being Crushed and Transported to Storage Area
2. Preparation : • To break up large clay lumps and stones, the material is processed through size-reduction machines before mixing the raw material. • Usually the material is processed through inclined vibrating screens to control particle size.
3. Forming. • Tempering, the first step in the forming process, produces a homogeneous, plastic clay mass. • Usually, this is achieved by adding water to the clay in a pug mill, a mixing chamber with one or more revolving shafts with blade extensions. After pugging, the plastic clay mass is ready for forming. • Tempering: To bring to a desired consistency, texture, hardness, or other physical condition by blending.
Clay is Thoroughly Mixed with Water in Pug Mill Before Extrusion
Next, the clay is extruded through a die to produce a column of clay. As the clay column leaves the die, textures or surface coatings may be applied. An automatic cutter then slices through the clay column to create the individual brick. Cutter spacing and die sizes must be carefully calculated to compensate for normal shrinkage that occurs during drying and firing.
4. Drying. • Wet brick from molding or cutting machines contain 7 to 30 percent moisture, depending upon the forming method. • Before the firing process begins, most of this water is evaporated in dryer chambers at temperatures ranging from about 100ºF to 400ºF (38ºC to 204ºC). • The extent of drying time, which varies with different clays, usually is between 24 to 48 hours. • In all cases, heat and humidity must be carefully regulated to avoid cracking in the brick.
Hacking • Hacking is the process of loading a kiln car or kiln with brick. • The number of brick on the kiln car is determined by kiln size. • The brick are typically placed by robots or mechanical means. • The setting pattern has some influence on appearance.
5. Firing. Brick are fired between 10 and 40 hours In tunnel kiln. In a tunnel kiln brick are loaded onto kiln cars, which pass through various temperature zones as they travel through the tunnel. The heat conditions in each zone are carefully controlled, and the kiln is continuously operated. Brick Enter Tunnel Kiln for Firing
5. Cooling. • After the temperature has peaked and is maintained for a prescribed time, the cooling process begins. • Cooling time rarely exceeds 10 hours for tunnel kilns. • Cooling is an important stage in brick manufacturing because the rate of cooling has a direct effect on color.
6. De-hacking. • is the process of unloading a kiln or kiln car after the brick have cooled, a job often performed by robots. • Brick are sorted, graded and packaged. • Then they are placed in a storage yard or loaded onto rail cars or trucks for delivery. • The majority of brick today are packaged in self-contained, strapped cubes, which can be broken down into individual strapped packages for ease of handling on the jobsite.
