BRICKS, BUILDING BLOCKS AND MORTARS. Lecturer: Prof. Dr. Mohammad Ismail Faculty of Civil Engineering, UTM-Skudai, Johor Darul Ta zim, MALAYSIA

Transcription

1 BRICKS BRICKS, BUILDING BLOCKS AND MORTARS Lecturer: Prof. Dr. Mohammad Ismail Faculty of Civil Engineering, -Skudai, Johor Darul Ta zim, MALAYSIA 1 December 6, 2013

2 BRICKS, BUILDING BLOCKS AND MORTARS 1. Materials in Construction, G.D.Taylor, 2 nd. Edition, Longman, Civil engineering Materials, N. Jackson and R.K. Dhir 5 th. Edition, Macmillan, Civil engineering Materials, S.Somayaji, 2 nd. Edition, Prentice Hall,

3 LEARNING OUTCOME At the end of a lecture: General knowledge on Brick and Blockwork Manufacture of Bricks Type and Classification Properties and Testing Application Mortar/render 3

4 Firaun said: O Chief! No god do I know for you but myself: therefore, O Haman! Light me a (kiln to bake bricks) out of clay, and build me a lofty palace, that I may mount up to the god of Moses: but as far as I am concerned, I think (Moses) is a liar! (Al-Qasas 28: 38) 4

5 INTRODUCTION MASONRY Masonry formed by combining individual masonry units, such as stone and brick, with a binding materials: mortar Mainly used to build walls-vertical structural elements, thin in their proportion to their length and height-that serve to enclose or divide a space and to support loads from other elements 5

6 One of the oldest construction materials 6 Pyramids,

7 JSB One of the oldest construction materials Great Wall of China, 7

8 JSB One8 of the oldest construction materials Taj Mahal of India

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10 JSB 10

11 Today, masonry is used in various types of application ranging from high-rise to water retaining structures Based on location: Exterior type Interior type Based on Structural requirement Load Bearing Non-load Bearing Based on Method of Construction Solid or Hollow wall Framed wall 11

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13 A masonry unit is a brick, tile stone, glass block, or concrete block 13

14 A masonry unit is a brick, tile stone, glass block, or concrete block 14

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16 MASONRY UNITS Masonry unit Solid Hollow Stone Glass Block Clay brick Concrete brick Structural clay tile Concrete Block 16

17 CLAY BRICK Clay brick is a small solid block, usually rectangular, of burned clay, block of concrete and sand-lime Most widely used size at present is the single standard metric brick 215x102.5x65 mm Made by pressing a prepared clay sample into a mould, extracting the formed unit immediately then heat it to sinter the clay 17

18 Basic Types of brick Common bricks Ordinary bricks, designed not to provide good finished appearance or high strength 18

19 Basic Types of brick Facing bricks Design to give attractive appearance, free from imperfections 19

20 Basic Types of brick Engineering bricks Designed primarily for strength and durability. High density and well fired 20

21 JSB 21

22 Indentations and Perforations in bricks Indentations (frogs) and perforations may be provided for Assist in forming a strong bond between the brick and the remainder of the structure Reduce the effective thickness of the brick and hence reduce firing time Reduce material cost without serious in-situ strength loss 22

23 Perforated bricks generally contains less than 25% 23 of voids

24 MANUFACTURE OF CLAY BRICKS CLAY PREPARATION Clay is prepared by crushing and grinding and mixing until it is of a uniform consistency Water may be added to increase plasticity (tempering) and in some cases chemicals may be added for specific purposes Barium carbonate which react with soluble salts producing insoluble product 24

25 MOULDING Moulding technique is design to suit the moisture content of the clay Semi-dry process This process utilises a moisture content in the region of 10%. The material is pressed into the mould in up to four stages. The faces of the brick may, after pressing, be textured or sand faced 25

26 Stiff plastic process This utilises clays which are tempered to a moisture content of about 15% A stiff plastic consistency is obtained, the clay being extruded and then compacted into a mould under high pressure 26

27 The wire-cut process The clay is tempered to about 20% and must be processed to form a homogeneous material This is extruded to a size which allows for drying and firing shrinkage and units are cut to the correct thickness by wires 27

28 Soft mud process This process utilises a clay, in a very soft condition, the moisture content being as high as 30% Breeze or town ash may be added to provide combustible material to assist firing or improved appearance The clay is pressed into moulds which are sanded to prevent sticking. The green bricks are very soft Hand-made bricks are produced by a similar process which produce great aesthetic appeal 28

29 DRYING Must be carried out prior to firing Drying enables such bricks to be stacked higher in the kiln without lower bricks becoming distorted Also enables the firing temperature to be increased more rapidly Drying is carried out in chambers and takes several days 29

30 FIRING Firing is to cause localised melting (sintering) of the clay which increases strength and decreases the soluble salt content without loss of shape of the clay unit The main constituents of the clay silica and alumina do not melt The main stages of firing are: 100 o C evaporation of free water 400 o C burning of carbonaceous matter o C sintering of clay Engineering bricks normally fired at higher temperature 30

31 CLAMPS Bricks are stacked in large special formations on a layer of breeze, though the bricks also contain some fuel The breeze base is ignited and the fire spread slowly through the stack, which contracts as the bricks shrink on firing The process may take up to one month 31

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33 CONTINUOUS KILNS Widely used, Comprise a closed circuit of about 14 chambers arranged in two parallel rows with curved ends Fire is directed to each chamber in turn Drying is carried out prior to the main firing process and is achieved by warm air obtained from fired bricks during cooling The kilns are describe as continuous, since the fire is not extinguished It is simply diverted from one kiln to the next 33

34 TUNNEL KILNS Recently introduced and can reduce firing time to ±1 day Units are specially stacked onto large trolleys incorporating a heat-resistant loading platform The trolleys then pushed end-to-end into a straight tunnel with a waist that fits the loading platform closely The bricks pass successively through drying, firing and cooling zones 34

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36 Types of BRICKS 36

37 CALCIUM SILICATE BRICKS BS 187 This bricks are made by blending together finely ground sand or flint and lime, ratio 10:1 The semi-dry mixture is compacted into moulds and then autoclaved, using high pressure steam for several hours Surface reaction occurs between the sand and lime, producing calcium silicate hydrates which glue the sand particles into a solid mass Compressive strength 7-50 N/mm 2 Good overall durability in clean atmosphere 37

38 CONCRETE BRICKS BS 6073 Recently introduced, comprising well compacted, low workability concrete mixes appropriate aggregate size, products of high strength and durability Color and texture can be similar with clay bricks Free from efflorescence, tending to shrink slightly in dry situations 38

39 39 JSB

40 BUILDING BLOCKS Rates of production during construction substantially greater with blocks than with brick-size units 100mm thick block of size 440 x 215 mm is equivalent to approximately six standard bricks 40

41 A great variety of sizes and types is available to suit purposes ranging from structural use to light weight partitions High quality surface finishes are obtainable 41

42 CLAY BUILDING BLOCKS Generally hollow units, since the voids result in Reduced firing times Reduced weight Increased handle ability Increased thermal insulation Made from well sintered clay dense, brittle and difficult to cut Not intended as finished facing materials 42

43 CONCRETE BLOCKS BS 6073, Also cover concrete bricks, can be solid hollow or cellular Solid blocks largely void less but may have grooves or holes to reduce weight or facilitate handling Hollow blocks these voids passing right through. Strength can be increased by filling the cavities with concrete, especially if reinforcement is included Cellular blocks a special type of hollow block, the cavities are closed at one end. Solid edge would be laid upwards 43

44 Thickness > 75mm: average strength of 10 blocks not less than 2.8 N/mm 2. no individual block less than 80% of this value Thickness 75mm. Average transverse strength of 5 blocks > 0.65 N/mm 2 Drying shrinkage should be < 0.06% (except autoclaved blocks) < 0.09% for autoclaved aerated blocks 44

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