rapport 1129 Potentialbedömning av flygaskor ...

VÄRMEFORSK
sary compressive strength. The results show that the compressive strength decreases if
wet-stored fly ash is used in the stabilised samples compared with the use of dry fly ash
instead.
Sediment
Sediments from the Port of Gävle entry channel are sulphatic silty sediments with approximately
5% organic content (TOC). Water quota is between 329 and 370%. The
sediment’s pollutant content and pollutant levels were compared to those in some other
Swedish ports and therefore can be considered representative of sediment in Swedish
ports.
S / S Treatment – Properties in Terms of Technology and Environment
Fly ashes A1–A5 were used as a binder together with C / M. No clear correlation
between the key parameters of fly ashes and the obtained compressive strengths of the
stabilised samples can be identified, except that the minimum compressive strength was
obtained with the fly ash with lowest CaO content and the maximum compressive
strength with a maximum content of CaO. The binder composition was 50% cement,
20% Merit 5000 and 30% fly ash (A1–A5). The amount of binder was 150 kg/m 3 .
Figure 1 presents the compressive strength results summarized for the stabilisation of
the two sediments and the five different binder mixtures. All binder mixtures A1–A5
passed the basic criterion of compressive strength > 140 kPa after 91 days, see Figure 1.
The median of the investigated sediments’ compressive strength was more than 500 kPa
after 91 days and the minimum compressive strength was about 300 kPa, which was
achieved with A2. The highest value was achieved with A1, around 780 kPa. All samples
yielded permeability values between 10 -8 m / s and 10 -9 m / s after 91 days. Since
batch test were performed on the stabilised material, the leaching of organic pollutants
is barely detectable. Even the leaching of metals was low in these tests.
Tryckhållfasthet. kPa
800
700
600
500
400
300
200
100
0
28 dygn 91 dygn
Figure 1 Compressive strength results as median, maximum and minimum values of the binder
mixtures A1–A5 for the investigated sediments. The amount of binders was 150 kg/m 3 – the
recipe mixture was C / M / A (50/20/30), where A is A1–A5.
Finances
In a s / s project, there are usually large volumes of dredged material to be stabilised,
which require large volumes of binders. Normally, the binder quantity is 100–200 kg/m 3
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