Abstract :
[en] Large quantities of construction and demolition wastes are produced each
year. In order to make good use of recycled concrete aggregates (RCA) in
concrete, it is very important to study the influence of the granular fraction
and the origin of RCA on their properties. In this study, RCA from industrial
produced blocks (RCA_Blocks) and slabs (RCA_Slabs) were crushed and
then separated into four granular fractions (0/2, 2/6.3, 6.3/14, 14/20 mm).
Each granular fraction of RCA was physically characterised. Real RCA from
recycling plant were also used for comparison. The results showed that
recycled sands offered significantly higher cement paste content (higher
bound water content) than coarse recycled aggregates. The fine RCA had
therefore a higher water absorption coefficient compared to coarser fractions
of RCA. The water absorption of finer fraction of RCA could be extrapolated
precisely from the relationship between water absorption and cement paste
content (or bound water content) of three coarse fractions of RCA. The values
of hardened cement paste content obtained for the RCA_Blocks were lower
than those measured on the RCA_Slabs, which was due to a smaller amount
of initial cement paste content in blocks. The results showed that RCA_Slabs
were more angular than RCA_Blocks.
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