Page 43 - SIM Guide to annual assessment_v2.0_Dec 2021

Silo

INSPECTION OF CONCRETE WALLS

Concrete Cracks

INCLUDES:
▪ Visual inspection + cracks measurement

oFine cracks (<0.2mm) visible from < 2m
oMedium cracks (0.2-0.4 mm) visible from 2-10m
oLarge cracks (>0.5mm) visible from >10m

NOTE:
▪Vertical cracks often appear first on the inside wall face
and then propagate to the exterior wall face.

REMARKS

▪Cracks> 0.5 mm indicates excessive stress. Design review (if not yet done) needs to be done.
▪Cracks with "I" shape and sharp edges indicate only small movement in the silo wall.
▪Cracks with "Y" shape are related to changes in the tension and compression stress near the
surface and should be more closely inspected.

▪Vertical cracks >0.5mm indicate static overloading of the silo wall caused by tension and/or
bending moments (= structural integrity of silo is compromised).

▪Single large vertical crack on the silo wall’s interior surface near its junction with an adjacent
silo. This can indicate extreme wall flexure combined with maximum tension (=
structural integrity of silo is compromised).
▪Hairline cracks in a crazed pattern on the wall’s exterior surface are caused by new concrete
shrinking should be considered as benign.

CATEGORIZATION:
Cracks > 0,5mm LFF= A (Almost Certain)
Cracks > 0,3mm LFF= B (Likely)
Concrete spalling and exposed rebar (big areas) LFF= A (Almost Certain)

Previous Reparations

INCLUDES:
▪ Check for the reopening of vertical cracks that have
been previously injected with epoxy material or similar

CATEGORIZATION

Reopening of cracks LFF= B (Likely)

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