BS EN 12390-17 pdf free download

BS EN 12390-17 pdf free download.Testing hardened concrete.
The drying room or cabinet shall meet the following requirements. a) Air shall be circulated through the room or cabinet so that the same specified conditions are attained adjacent to all specimens under test. The air velocity should not exceed 0,5m/s near the specimens. b) The temperature in the room or cabinet shall be maintained at (20 ± 2) °C. c) The relative humidity in the room or cabinet shall have a target value of between 50 % and 70 % and maintained within ± 5 % of the target value. Other values may be used if allowed by national provisions valid in place of use. d) The temperature and relative humidity of the room or cabinet shall be monitored throughout the duration of the test and recorded at intervals not exceeding 24 h. Separate provisions may be required in the case of manual recording of data during laboratory closure periods. The drying room or cabinet shall be fitted with suitable racks for storing specimens. The racks shall permit free circulation of air around specimens, except for necessary supports, and shall be so situated with respect to the nearest wall or other obstruction that air circulation is not restricted in the intervening space. The horizontal supports shall consist of non‑absorptive members having a total bearing width supporting the specimen of not more than 25 mm. 5.3 Length change measuring system 5.3.1 General The length change measuring device shall have a resolution of at least 0,001 mm. The maximum permissible error of for gauge lengths of 400 mm or more shall be ± 0,01 mm and for gauge lengths less than 400 mm it shall be ± 0,005 mm. Gauges relying on friction contact shall not be used. 5.3.2 Callipers or rule The callipers or rule shall be capable of determining the initial gauge length with a maximum permissible error of ± 2,0 mm for gauge lengths of 400 mm or more and ± 1,0 mm for gauge lengths less than 400 mm. 5.3.3 Reference bar (optional) If a specific reference bar is required, it shall be made of invar metal or other material that has a similar coefficient of expansion over the range of test temperatures. The reference bar shall be compatible with the measuring apparatus used. The central section of the reference bar may be covered by a thermal isolating material to minimize the effect of temperature change during handling. 5.4 Balance The balance shall be capable of weighing the specimens with a maximum permissible error of ± 0,02 % of the mass. 5.5 Gauge studs When used, gauge studs shall be made of a hard non‑corrosive material that does not react with the concrete and which can be securely fixed on or within the concrete, taking care that no mineral oil or other contaminant remains on the surface of the gauge stud that comes into contact with the concrete.The design of the studs shall be compatible with the measuring apparatus used. Side face gauge studs shall be arranged such that they are located on a minimum of two measuring lines spaced uniformly around the periphery of the specimen parallel to the principal axis or in two planes. In the case of measuring between planes, at least three gauge studs in each plane are used (see Figure 1). Gauge studs may be fixed to the surface by gluing (adhesion method) or cast into the concrete (embedded method). For prisms, the gauge studs shall not be located on the trowelled face or bottom formed face as cast. 5.6 Gauge length The gauge length shall be at least L/2, where L is the specimen length, with the measuring points symmetrically positioned and not located within d/3, where d is the specimen diameter or width, of the end of the specimen.BS EN 12390-17  pdf download.