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Transverse
strength AS 4046.3
This test
measures the force required to break the tile in half. Tiles
are first soaked in water for 24 hours, then supported on battens
cut to fit the tile profile and loaded via another shaped batten.
The results are expressed in newtons and can be compared
against the requirements of AS 2049.
Water
absorption AS 4046.4
Pieces of
water-saturated tile are weighed, dried in an oven and re-weighed
to measure the water absorption as a percentage of the dry weight.
AS 2049 sets out a maximum value for "general purpose"
tiles.
Permeability AS
4046.5
To determine
whether water can penetrate a tile, a dam is set up on the top
surface of the tile by sealing the bottom edge of a shaped
enclosure to the tile, filling the enclosure to a depth of 50 mm
with water, and seeing whether any drops form on the underside of
the tile over a 2-hour period.
Resistance to
salt attack AS4046.7
Salt can cause
damage to roof tiles, by chemical attack or by the expansive effect
of salt crystals forming in the pores of a tile, or a combination
of both. To assess how resistant a tile is to this, small
pieces are alternately soaked in a salt solution, dried in an oven,
soaked again etc, for 40 cycles. The amount of material
that's crumbled or flaked off the surface during this process
determines whether the tile can be classed as exposure grade.
This is of most relevance in coastal situations.
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