Clay brick manufacture - Construction Industry Development Board

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5.4 Mortar 29 5.4.1 Mix proportions 29 5.4.2 Cement 31 5.4.3 Lime 31 5.4.4 Sand 31 5.4.5 Mortar plasticisers 32 5.4.6 Pigments 32 5.4.7 Ready-mixed mortar 32 Part 6 CLEANING OF CLAY BRICKWORK 35 6.1 General precautions 35 6.2 Preparation 35 6.3 Mortar and mortar smear 35 6.4 Lime and lime bloom 36 6.5 Vanadium 36 6.6 Efflorescence 36 6.7 Lichens and mosses 36 6.8 Running water 36 6.9 Various oils 36 6.10 Paint 36 6.11 Rust or iron 36 6.12 Manganese 37 6.13 Timber 37 6.14 Smoke and soot 37 6.15 Tar 37 6.16 Large projects – multi-storeyed buildings 37 Part 7 CONSTRUCTION DETAILS 35 Acknowledgements 38 2
1.1 BRICK MANUFACTURE Bricks made by shaping a plastic mass of clay and water, which is then hardened by drying and firing, are among the oldest and most enduring of mankind’s building materials. Until comparatively recent times the clay was dug, the bricks were made and the kilns set or drawn by manual labour with help from animal power. About 100 years ago, the first effective machines for brick production appeared, and the trend towards mechanisation of clay winning, making and handling operations has continued at an increasing pace to the present day. Brick is the simplest and most ancient of all building materials. Few other fabricated building units have enjoyed such widespread and continuous popularity. This enduring public acceptance is based on the unique combination of the properties offered by brick to the owner and builder. This single material can be used to enclose a structure with a decorative, load-bearing wall, which is exceptionally durable and, if properly constructed in the first place, requires practically no maintenance. Because of the versatility of the raw material, which can readily be moulded into a great range of shapes and sizes, and the flexibility that this gives to design and construction, building in brick has remained cost-effective. Secondary clay materials are compounds of alumina, silica with minor amounts of lime, magnesia, soda or potash. Iron compounds, usually the oxides, hydroxides or carbonates, are nearly always present as impurities in brick clays, and they account for most of the wide range of colours found in the finished product. Clays containing up to 3% of iron oxide give white to cream or buff colours, which change to pinks and reds as the iron oxide content rises to between 8 and 10%. By adding manganese dioxide in proportions from 1 to 4%, a range of grey and brown colours can be produced. More important than their chemical composition are the facts that: • when mixed with water, the clay minerals give a plastic mass that can be shaped by pressure to form a brick; Part 1 CLAY BRICK MANUFACTURE • at economically practical temperatures ranging between 1 000˚ to 1 200˚C, the clay particles can be fused into a cohesive mass of great compressive strength; • controlled evaporation of the free water surrounding the particles in plastic clay minimises excessive shrinkage and defects in the structure of the brick. Modern brick manufacture involves high speed processing at extrusion rates of up to 25 000 bricks per hour. Solid bricks of the size traditional in South Africa (222 x 106 x 73 mm) weigh 3 kg to 3,5 kg. Therefore, 1 000 finished bricks weigh approximately 3,5 tonnes. In the wet state before firing, the clay is heavier. For every 1 000 bricks at least 4 tonnes of material must be dried, fired to a temperature of 1 000˚ to 1 200˚C (depending on the clay used) and cooled down. 3
Page 1: Contents Part 1 CLAY BRICK MANUFACT
Page 5 and 6: To reduce the drying cycle, brickma
Page 7 and 8: Part 2 THE LANGUAGE OF CLAY BRICKS
Page 9 and 10: Standard testing is carried out on
Page 11 and 12: 3.6 OTHER PROPERTIES 3.6.1 Durabili
Page 13 and 14: Fire resistance rating is a measure
Page 15 and 16: SABS 0249 recommends design for pot
Page 17 and 18: Figure 5: Location of control joint
Page 19 and 20: 5.1 STRUCTURAL DESIGN REQUIREMENTS
Page 21 and 22: 5.2.3 Dimensions of masonry walls i
Page 23 and 24: Figure 6: Acceptable method of step
Page 25 and 26: 5.2.5 Minimum thickness of foundati
Page 27 and 28: Cavity walls A cavity wall consists
Page 29 and 30: 5.4.2 Cement Cements for use in mor
Page 31 and 32: The mortar contains a regulator, wh
Page 33 and 34: 6.4 LIME AND LIME BLOOM Follow trea
Page 35 and 36: 39 The construction details that fo
Page 37 and 38: 41 Internal footing Internal footin
Page 39 and 40: 43 Facebrick externally with quarry
Page 41 and 42: 45 External brick wall with quarry
Page 43 and 44: 47 Steel window with plaster extern
Page 45 and 46: 49 Placement of dpc in two leaf bri
Page 47 and 48: 51 Brick lintel for an external fac
Page 49 and 50: 53 Brick lintel for facebrick exter
Page 51 and 52: 55 Brick on edge lintel for facebri

Clay brick manufacture - Construction Industry Development Board

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