Bricks & Pavers Technical Manual - Boral

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Bricks & Pavers Technical Manual Section 1.1 Brick Properties 1.103 Water Absorption Cold Water Absorption The amount of water that a brick can absorb is measured by the cold water absorption test. There is no distinct relationship between water absorption and the water-tightness of walls. The results of water absorption tests are used by the brick manufacturer for quality assurance. Initial Rate of Absorption The initial rate of absorption (IRA) is the amount of water absorbed in one minute through the bed face of the brick. It is a measure of the brick’s ‘suction’ and can be used as a factor in the design of mortars that will bond strongly with units. As mortars other than the ‘deemed to comply’ mortars are rarely used, the impact of the IRA is primarily on the bricklayer. Bricklayers, through practical experience, adjust the mortar, the height of a wall built in a day and the length of time before ironing the joints, according to the suction. The bond between the masonry unit and mortar is largely influenced by the capacity of the brick to absorb water and the ability of the mortar to retain the water that is needed for the proper hydration of cement. If the brick sucks the water too quickly from the mortar, the next course may not be properly bedded. If the mortar retains too much water, the units tend to float on the mortar bed, making it difficult to lay plumb walls at a reasonable rate. In either case there will be poor bond. The optimum value of IRA is considered to be between 0.5 and 1.5 kg/m2 /min. However, IRAs can exceed these limits. The mortar’s water retentivity should be matched to the brick type where good bond strength is critical. ■ ADV03745
Bricks & Pavers Technical Manual Section 1.1 Brick Properties 1.104 Durability Salt attack is the most common durability problem affecting bricks. In the form of a solution, salt can be absorbed into masonry. As the water evaporates, the salt is drawn towards the outside face. The evaporating water leaves the solution super-saturated so salt crystals begin to form. The salt crystals grow in the pores just below the surface and depending on the texture of the brick, the amount of salt, the rate of drying and the temperature, the salt may fill the pores, exerting very high pressures on the matrix. The energy in the constrained salt crystal increases and if sufficient ‘pops’ a piece of the outer surface off and salt attack has begun. Bricks are assessed and classed into three grades according to AS/NZS4456.10 Resistance to Salt Attack. In summary the three grades of brick that can be used are as follows: • Protected Grade (PRO) Suitable for use in elements above the damp-proof course in non-marine exterior environments. Elements above the damp-proof course in all exterior environments, with a waterproof coating, properly flashed junctions with other building elements and a top covering (roof or coping) protecting the masonry. • General Purpose Grade (GP) Suitable for use in an external wall, excluding walls in severe marine environments or in contact with aggressive soils and environments (see AS3700 Appendix E). General purpose grade bricks can also be used in PRO applications. • Exposure Grade (EXP) Suitable for use in external walls exposed to severe marine environments, i.e. up to one kilometre from a surf coast or up to 100 metres from a non-surf coast or in contact with aggressive soils and environments. The distances are specified from mean high water mark. Exposure grade bricks can also be used in PRO and GP applications. Boral bricks are classified as either EXP or GP. ■ ADV03746
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2.1 Paver Properties
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2.2 Pavement Design
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2.4 Clay Paver Property Tables
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3 Face Brick Range 3. Face Brick Ra
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5 Paver Range 5. Paver Range
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Projects In View PIV, Boral’s pub
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Free Clay Brick and Paver Samples F
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Bricks & Pavers Technical Manual - Boral

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