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| The preliminary actions recommended for POP ceiling over wooden strips are as follows: |
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| The plaster of Paris shall be of the calcium-sulphate semi-hydrate variety. |
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| When sieved through a sieve No. 3.35 mm for 5 minutes after drying the substance, the fineness of POP shall not be more than 1% by weight. |
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| It shall not be too quick setting. |
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| Initial time setting shall not be less than 13 minutes. |
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| The average compressive strength of the material determined by testing 5 cm. cubes after removal from molds and after drying for 24 hours in an oven at 40 degree C till weight of the cubes is constant, shall not be less than 84 kg. Per square meter. |
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