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

AS 1012.9:2014 pdf free download – Methods of testing concrete Method 9: Compressive strength tests—Concrete, mortar and grout specimens.
(e) Cored specimens that are to be tested in the dr condition shall be tested within 2 h of removal from the conditioning environment.
6.1 General
Where capping is required, the specimens shall he tested using either
(a) a rnouldcd capping, prepared in accordance with Clause 6.2; or
(b) a restrained natural rubber capping system complying with the requirements of Clause 6.3, provided compressive strength is expected to he greater than 10 MPa and less than 80 MPa.
6.2 Moulded capping materials
6.2.1 General
Moulded caps shall he as thin as practicable, hut not thicker than 6 mm. Only one layer of capping material shall be used on each surface requiring capping, hut small depressions may be filled prior to capping. Moulded capped surfaces shall not depart from a plane by more than 0.05 mm.
6.2.2 Prej;aration of capping materials
Moulded capping materials shall consist of one of the following, subject to the limitations on use set out in Clause 6.4:
(a) Filled sulphur mixtures Mixtures of sulphur and at least 10% by volume of line filler material such as fly ash, finely ground silica or tire clay, or cement may be prepared. The sulphur mixture shall be used at a temperature that ensures a suitable viscosity for capping.
(b) Portland cement niorlar Mortar made from a mixture of one part of Portland Cement and one part of fine sand, provided that the water-cement ratio does not exceed 0.35. may be prepared. The Portland cement shall be fresh, free from lumps, and shall comply with the requirements of AS 3972.
The sand-cement mixture shall be mixed with water to form a stiff paste which shall be allowed to stand for not less than 0.5 h and not more than 2 h before use, to minimize shrinkage of the cap.
(c) High-alumina cement mortar Mortar made from one part of high-alumina cement and one part of fine sand, provided that the water-cement ratio does not exceed 0.35. may be prepared. The high-alumina cement shall he fresh and free from lumps.
The sand-cement mixture shall he mixed with water to form a stiff paste which shall be allowed to stand for not less than 0.5 h and not more than 2 h before use, to minimize shrinkage of the cap.
(d) Cement passes Portland cement or high-alumina cement paste or mixtures of these may be used to prepare caps if the cement used is fresh and free from lumps.
The cement shall be mixed with water to form a stiff paste and used within 2 h.
(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 he 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 10 mm. 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 be 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 specifled 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.