CPD Specifier May 2015 issue January 2015 | Page 48

Structural Repair

Resin bearing the load

Oxford Hydrotechnics use innovative epoxy resin solution to repair
bearing erosion caused by on-track movement
Oxford Hydrotechnics were approached by the
client to devise a solution to repair damage
to a brickwork arch beneath a rail bridge.
The problem was deemed to be the result
of excessive vertical movement of cast iron
troughs on their bearings, particularly when the
bridge was carrying a train load above.
The issue had resulted in Network Rail being
forced to reduce the line speed on the section
of track that passed over the bridge as a
precautionary measure and urgent remedial
works were scheduled. Proposed solutions
included masonry pinning using helical ties and
some form of grouting solution to arrest the
movement of the troughs.
It was deduced that, as there was no evidence
of spoil falling out of the bridge, the bearing
areas had been subjected to a crushing action
only, and that this would not have created large
voids within the structure.
H2OX engineers concluded that a cementitious
grouting solution would not necessarily work, as
it would not have been of a low enough viscosity
to flow through the pulverised engineering
brickwork.

Oxford Hydrotechnics proposed an alternative
approach, using a very low viscosity epoxy resin
(Oxford Hydrotechnics’ EP1390 product) which
would allow permeation through the brickwork.
A temporary propping system was installed
beneath the bridge, with H2OX inflating served
grout bags to ensure full support whilst the work
took place.
A grid pattern of injection ports was then drilled
into the bearing area at the end of each trough,
almost through to the extrados of the arch.
Injection packers were then installed at a
shallow depth. allowing resin to flow into the
structure, permeating the crushed brickwork and
curing at a high compressive strength (>80N/
mm2).
The epoxy resin was injected until refusal.
Particular emphasis was placed on filling the
interface between the trough ends and the
bearing brickwork to prevent future movement.
Following completion, including a 48hr period to
allow adequate curing time for the epoxy resin,
the temporary propping system beneath the

bridge was removed and the line speed of the
track above was restored to its former limit.
The project took a total of 9 shifts from start
to completion, using both day and night shifts,
delivering quick and highly successful results for
the client.

Leak Sealing - Ground Stabilisation - Void Filling - Structural
Repairs - Concrete Repairs - Cement Grouting
OXFORD HYDROTECHNICS

TEL: [phone]

WWW.H2OX.NET

READER ENQUIRY NO: 63

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