BS EN 12390‑17:2019 pdf download.Testing hardened concrete Part 17: Determination of creep of concrete in compression.
6 Test specimens 6.1 Shape and dimensions The test specimens shall be moulded (cylinder or prism) complying with the requirements of EN 12390‑1 with the exception of nominal dimensions or cores complying with the requirements of EN 12504‑1. The ratio between the specimen length L and the dimension d shall be in the range 2 ≤ L/d ≤ 7. If gauge studs are used, the moulds shall allow for the embedment of gauge studs in the specimen. The size of the specimen has an influence on the total strain recorded. For comparison of results obtained from specimens with different shape or dimensions, the concept of notional size h 0 may be used (see EN 1992‑1‑1:2004, 3.1.4). It is recommended to have at least 2 specimens for the determination of creep Sufficient specimens should be taken to enable the determination of shrinkage and if required secant modulus, testing at different ages. The determinations of shrinkage and creep shall be made on specimens of the same shape and dimension d, from the same batch of concrete and subjected to the same conditions of storage prior to and during testing. Companion specimens shall be available for the determination of compressive strength as described in 7.3 and shall be made from the same batch of concrete.
7 Procedure 7.1 Demoulding and preparation of specimens Specimens shall be demoulded at (24 ± 1) h from the time of casting. Where variations to this time period are necessary, full details shall be noted in the report. On removal from its mould, each specimen shall be marked with its own unique identification. When used, surface adhesion studs shall be securely fixed before the commencement of the test. After demoulding and fixing of gauge studs (if applicable), the specimen(s) shall be weighed, the mass recorded and the gauge length (L 0 ) measured and recorded. The specimen(s) shall then be placed in the drying room or cabinet. The alignment of the axes of the individual specimens is critical and the end preparation necessary to achieve this alignment is likewise critical. Great care shall be exercised in achieving the flatness and perpendicularity within the tolerances specified in EN 12390‑1. The requirements for flatness and perpendicularity may be met by capping with Portland cement mortar or sulphur, by grinding, or at the time of casting by fitting the ends with steel bearing plates normal to the axis of the specimen. 7.2 Curing, storage and conditioning For total creep, after demoulding, specimens shall be stored in accordance with EN 12390‑2 up to the time t 1 (wet curing), and then stored in the drying room or cabinet in accordance with 5.2 up to the time t 2 (drying curing) where t 1 and t 2 are defined prior to commencing of the test. t 1 may be equal to the demoulding time (no wet curing) and t 2 may be equal to t 1 (no drying curing before loading) For basic creep, after demoulding, specimens shall be contained and sealed within a protective envelope, e.g. coating with a resin, application of a suitable metal foil, or direct application of a self‑adhesive foil and shall be stored at (20 ± 2) °C before loading. Containment and sealing may also be done when cast, using a suitable metal foil that fits into the mould.BS EN 12390‑17 pdf download.