Abstract： AS 1012.9:2014 pdf download.Methods of testing concrete Method 9: Compressive strength tests-Concrete, mortar and grout specimens. (a) Cement mortar or paste, and special gypsum plaster caps shall be formed against plate-glass, or a machine...

AS 1012.9:2014 pdf download.Methods of testing concrete Method 9: Compressive strength tests-Concrete, mortar and grout specimens.

(a) Cement mortar or paste, and special gypsum plaster caps shall be formed against plate-glass, or a machined metal plane plate,

at least 6 mm thick. The diameter of all such plates shall be at least 25 mm larger than the nominal diameter of the specimen. and the surfaces shall not depart from a plane by more than 0.05 mm.

(b) Caps made from sulphur mixtures shall be formed against a metal plate in which a recess has been machined. The thickness of the metal in the recessed area shall be at least 10mm. The base of the recess shall be a circle whose diameter is approximately 5 mm

greater than the nominal diameter of the specimen. The side of the recess shall slope to facilitate removal. The recessed area

shall not depart from a true plane to an extent that results in caps with surfaces which themselves depart from a plane by more

than 0.05 mm,

(c) Capping plates shall he thinly coated with mineral oil to prevent adhesion of the capping material to the plate.

(d) Alignment devices shall be used in conjunction with the plates to ensure that the specified perpendicularity of the cap to

axis of the specimen is obtained.

6.2.4 Capping procedure

Concrete cylinders prepared in the laboratory may be capped with cement mortar after the concrete has ceased settling in the mould, generally 2 h to 4 h after moulding.

Hardened concrete cylinders and cores shall he capped in accordance with the following procedures:

(a) Where a cement mortar or paste, or special gypsum plaster cap is to be applied, ensure that the end of the cylinder is in the

saturated surface-dry condition just prior to capping.

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