Free Moisture and Absorption
of Aggregates
The moisture content and absorption of aggregates are
important in calculating the proportions of concrete mixes since any excess
water in the aggregates will be incorporated in the cement paste and give it a
higher water/cement ratio than expected.
§ All moisture conditions are expressed in terms of oven
dry unit weight.
Moisture conditions of aggregates:
Oven-dry Condition:
All free moisture, whether external surface moisture
or internal moisture, driven off by heat.
Air dry:
No
surface moisture, but some internal moisture
remains.
Saturated-surface dry
condition (SSD):
Aggregates
are said to be SSD when
their moisture states are such that during mixing they neither absorb any of
the mixing water added; nor they contribute any of their contained water to the
mix.
Note
that aggregates in SSD condition may possess “bound water” (water held by
physical chemical bonds at the surface) on their surfaces since this water cannot be easily removed from the aggregate.
Damp or Wet condition:
Aggregate
containing moisture in excess of the SSD condition.
Free Moisture and Absorption of Aggregates
Reviewed by Engineer
on
09:16:00
Rating:
Reviewed by Engineer
on
09:16:00
Rating:
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