Again, this is from my personal list and I can't remember where it came from.
However, I think it works in your context.
The civil engineering dictionary does give one of the meanings of casing as formwork for concrete

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Note added at 2002-05-14 22:07:13 (GMT)
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Yes, they drive in piles, so why wouldn\'t they drive in the casing?
Will double check. Meanwhile found this. Copying it here for my future reference too:
Extracting temporary casing


After concreting, extraction of the temporary casing can create problems particularly if delays occur and partial separation of the casing is obviously aggravated by the use of dirty or dented casings. With unsuitable mix designs, it is not unknown forth casing to be withdrawn still filled with concrete. Difficulties arise in pulling the casing if low slump concrete is used, or if the aggregate is particularly angular. Insistence on vibration the concrete can lead to arching with the casing. However the use of external casing vibrators has been found to be beneficial. Bleeding of mixing water from the joints of screwed casings may cause local consolidation of the concrete, leading to disturbance of the reinforcement cage and difficulty in extracting the casing.

Cavities outside the casing can lead to serious defects in the pile, particularly if they are water filled. If air filled voids exist outside the casing, defects are not structurally as serious. Normally the concrete in the shaft would slump to fill the cavity resulting in bulbous projections. There is a danger that debris can be dragged into the pile shaft, particularly if large cavities exist. Dry voids may form where thin gravel layers exist or where piles are formed in fill. Formation of such voids can be reduced by the use of a vibrator to insert the pile casing. Obviously, if there is any doubt that satisfactory pile shafts will be constructed, thin permanent casings should be used to support the soil.

Where slumping of concrete into voids has occurred, topping up the shaft with fresh material frequently leads to problem. Debris may be dislodged by removal of the casing or the placement of additional concrete and incorporated in the pile shaft.

http://www.envf.port.ac.uk/projects/piling2/done/Extracting ...

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Note added at 2002-05-14 22:12:58 (GMT)
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3701-28-12 Construction, surface design, maintenance, and ...
File Format: PDF/Adobe Acrobat - View as HTML
... is installed by manually or mechanically driving the casing into the ground. (B ... space
between a permanent casing and temporary casing shall be filled with grout ...
www.odh.state.oh.us/rules/final/chap28/FR28_12.pdf - Similar pages

Chapter 4
... fluid is present between the temporary casing and permanent casing or between the ... on
a permanent casing installed without driving and which is to be grouted in ...
www.lchd.org/sancode4.htm - 29k - Cached - Similar pages

SOILS-L digest for AUGUST 1994
... To summarize, this involves driving a temporary casing of plumbing pipe into the
substrate, inserting small flexible plastic tubing with screened ends, and ...
ibiblio.org/pub/academic/agriculture/agronomy/ SOILS-L/log9408.soils-l.html - 19k - Cached - Similar pages

REPORT OF THE INVESTIGATION PANEL ON ACCOUNTABILITY
... auger to excavate the boreholes when the method statement called for a vibrator driving
a 2.5m temporary casing wide enough to take a 2.3m permanent lining and ...
www.housingauthority.gov.hk/eng/ ha/piling/html/app1_5.htm - 11k - Cached - Similar pages

REPORT OF THE INVESTIGATION PANEL ON ACCOUNTABILITY
... from Houston Machinery Ltd. As indicated by the Panel\'s advisors, a vibrator is
not suitable for driving a temporary casing below 40 m. The possible range is ...
www.housingauthority.gov.hk/eng/ ha/piling/html/app2_02.htm - 10k - Cached - Similar pages
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