Innovation in
Architectural Design and Construction
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Foto
2 - 2% mix
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HIGH
PERFORMANCE CRC PRE-CAST REINFORCED CEMENT
COMPOSITES
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CRC durability
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The CRC matrix is
extremely dense and has no capillary porosity only gel
pores which is the reason for a very low permeability.
However, CRC will mostly be used in structures with a
service load considerably higher than that, which is
sustained on a structure of conventional concrete. This
made it necessary to perform investigations to
demonstrate the rate of penetration of chloride ions on a
heavily loaded structure. This is investigated in a
special testing rig, where small beams are exposed to
chlorides while loaded to a specified deflection. The results of these investigations are
available.. they show, that even with a high flexural
stress in the beams (70 Mpa),the rate of chloride
penetration is not accelerated compared to beams with no
load. The number of micro cracks in the beams is in
creased at high loads, but the micro cracks have a size,
which does not affect chloride penetration. The tests
show, that even with a severe chloride exposure it will
take more than 100 years before the service life
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CRC ability |
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CRC is thixothropic, which
means it responds well to vibrations. A slump test is not
very well suited for measuring the work ability of CRC,
but as the slump test is universally known and very
simple to perform, the effect on slump of varying the
content of fibres is shown in the following pictures.
Shimizu, Japan carried out tests with fibre contents of
2, 6 and 9% by volume. 6% by volume corresponds to about
450 kg per m3. Shown in the pictures below are results of
a slump test on the 2% and the 6% mix. A 2% mix has been
used for most pre-cast applications while a 6% mix is
used for CRC Joint-Cast applications. |
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