5Hand Made Bricks Formed into shape Fired at 1200°C Expensive Sizes VaryVery Soft – will not take mechanical anchorsOlder areas of Sydney
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7Note – Clay is not Compressed Certain images and/or photos on this page are the copyrighted property of 123RF Limited,its Contributors or Licensed Partners and are being used with permission under license.These images and/or photos may not be copied or downloaded without permission from 123RF Limited.
8Certain images and/or photos on this page are the copyrighted property of 123RF Limited, its Contributors or Licensed Partners and are being used with permission under license.These images and/or photos may not be copied or downloaded without permission from 123RF Limited.
9Voids due toLack of CompactionDistortion due tono compactionEdges not properlyformedShrinkage due tono compaction
28Holes in BricksThese are extruded bricks and the holes are called core holes or perforations that allow the brick to be fired more evenly.The Australian Standard states that core holes of up to 30 % of the material thickness have no effect on the insulation or fire resistance value of the brick.
29Calcium SilicateThe raw materials for calcium silicate bricks include lime mixed with quartz, crushed flint or crushed siliceous rock together with mineral colourants. The materials are mixed and left until the lime is completely hydrated, the mixture is then pressed into moulds and cured in an autoclave for two or three hours to speed the chemical hardening. The finished bricks are very accurate and uniform, although the sharp arrises need careful handling to avoid damage to brick (and bricklayer). The bricks can be made in a variety of colours, white is common but pastel shades can be achieved.
30Holes in BricksHoles Reduce WeightHoles allow the mortar to bind
32DurabilityBuilding Code of Australia (BCA) states that masonry units must be classified and used in the exposure conditions appropriate to their classification
33DurabilityAustralian Standard AS 3700 (Masonry Structures) provides details of these classifications
34DurabilityBrick is permanent. Once it's built it remains weatherproof and age proof. Brick doesn't get tired like man-made materials, so it requires virtually no upkeep or repairs. Bricks don't rust or erode, rot or decay, bend, twist or warp. Brick is a great protector - against the extremes of the Australian climate - heat and cold.Australia is a country of extremes. At any one time, different parts of our continent can be experiencing bushfires, floods, severe storms and drought. And climate change researchers suggest that conditions may soon become even more extreme. Many brick buildings only improve their appearance with age - The Great Wall of China is still looking great after more than 2,000 years
35Durability - FireBricks are non-combustible and don't assist the spread of fire, making them ideal for building in bushfire-prone areas. Clay bricks normally do not suffer any structural damage after a fire and can be re-used even as load bearing walls. After all, Bricks are kiln-fired at temperatures up to 1200 degrees Celsius (a standard kitchen oven operates up to about 250 degrees Celsius). Bricks alone won't fire proof a building - timber and plastic are flammable and glass shatters in the heat - but building in brick will provide a strong foundation to protecting your investment
36Durability - PestBricks don't get attacked by pests - termites don't eat it, rats don't gnaw at it, birds can't stain it. Bricks are unattractive to termites because they can't chew them - unlike timber. Cavity brick construction offers the ultimate in termite resistance, by eliminating timber framing in walls.
37Durability - WeatherMost brick colours and textures hide rain streaking, whereas plain or painted wall finishes such as render tend to show these and if damaged, are expensive and time-consuming to repair. Salt-safe and exposure grade bricks If you are building within 1km of surf coast and 100m of non-surf coast, or on harsh soils (such as former tip sites or converted industrial land) you should use Exposure Grade bricks. These bricks are made to withstand high salt conditions. In conditions like these, Exposure Grade bricks are the most affordable building material - designed for harsh Australian conditions
39Cleaning of BricksIdeally brickwork should be cleaned as it is laid. This is the simplest, cheapest and most effective method. Mortar smears should be cleaned as soon as possible using a scrubbing brush, running water and a sponge. Acid cleaning is only required if the mortar smears are allowed to harden and should be viewed as a last resort.
40Degradation of Brickwork FrettingExpansionPoor BondingLime Pitting
42Degradation - Fretting Fretting is caused by the action of salt migration in the walling system.Water with salt enters the brickworkWater dries out & salt is left behind as salt crystals.Salt crystals grow in the voids within the brick. As more salt is left behind by the evaporation of water, the salt crystal grows larger and larger.The strength of the growing salt crystal can be stronger than the elements that hold the brick together.If this occurs, the brick face begins to crumble and fall away. This is also true for mortar joints.
43Degradation - Fretting For salt attack to occur the following three conditions are required:There must be salts presentThere must be water entering the wallThe water must evaporate from the wallThe absence of any of these conditions will prevent salt attack.
44Degradation - Fretting When treating fretting, "prevention is the best cure". The source of the salt may be airborne salt from sea spray or salts that are naturally present in the soil, or introduced by fertilizers and salt-water swimming pools. The use of bore water may also provide the source of the salt.
45Degradation of Brickwork FrettingExpansionPoor BondingLime Pitting
46Degradation - Expansion Bricks undergo long-term permanent expansion over time.This expansion continues for the life of the brick, but the majority of the growth occurs early in its life.Most general purpose bricks have a coefficient of expansion in the range of mm/m (millimetres per metre) over fifteen years.
47Degradation - Expansion The typical problems arising with expansion gaps include:Inadequate sealingFailure to ensure that the gaps are clean and that no hard materials such as mortar droppings are left before sealingThe use of joint fillers that are too rigid, which have compressive strengths high enough to transfer forces across the joint.However, these problems can be avoided by good workmanship during construction. Further information on expansion gaps is available in CBPI Manual 10; Construction Guidelines for Clay Masonry
48Degradation of Brickwork FrettingExpansionPoor BondingLime Pitting
49Degradation – Poor Bonding The initial rate of absorption (IRA) is a function of the size and extent of the porosity of the bricks. The IRA is a measure of how quickly a brick will absorb water. The test method for initial rate of absorption is given in AS/NZSThe ability of bricks to absorb water affects the bond formed between brick and mortar. A tug-of-war occurs between the bricks ability to absorb water and the capacity of the mortar to retain water. If either the brick or the mortar wins, a poor bond will result. Therefore, the water retentivity of the mortar needs to be matched to the IRA of the bricks to ensure that a strong bond forms
50Degradation of Brickwork FrettingExpansionPoor BondingLime Pitting
51Degradation – Lime Pitting Lime pitting is an imperfection occurring in the surface of a brick due to the expansion of large lime particles just below the surface. The lime originates from the raw materials used in the manufacture of the bricks.Lime pitting is observed when the lime particles are present just below or on the surface of the brick. The volume expansion of the lime particle, resulting from the presence of moisture, can cause it to pop out of the brick or break the brick surface, generating a defect. An example of a large lime pit is shown below
53MortarMortar mixes are always specified as the proportion of cement to lime to sand. For example, a common mortar made from Portland cement has one part cement, to one part lime and 6 parts of sand is abbreviated C1:L1:S6 or 1:1:6 (the chief cementing agent will always be expressed as one). The type of mortar mix is classified according to the Australian Standard AS 3700 as M1, M2, M3 or M4. The grade chosen by the masonry designer should match the requirements of the design. AS 3700 lists the deemed-to-satisfy proportions for the various grades