Designation: c 157/C 157M – 08 Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete 1
Procedure for Mixing Mortars and Concrete
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| 8. Procedure for Mixing Mortars and Concrete
8.1 If the mortar or concrete to be tested is made in accordance with requirements other than those given in one of the following paragraphs, samples shall be taken and speci- mens molded as described in the sections on sampling and on molding specimens. 8.2 Bring all materials to a temperature between 65 and 75 °F [18 and 24 °C] before using to make mortar or concrete. Proportion solid materials by mass (that is, not by volume). It is permissible to batch water and liquid admixtures either by mass or by volume. For calculation of batch quantities, assume aggregates to be saturated and surface-dry; if they are not in this condition at the time of use, apply appropriate corrections, as necessary, to batch quantities to compensate for absorption or free moisture. 8.3 Mortar—Mix mortar in a mechanical mixer as de- scribed in Practice C 305 . The clearances between paddle and bowl specified in Practice C 305 are suitable only for mortars made with fine aggregates that are finer than the 2.36 mm (No. 8) sieve. Mortars made with aggregates containing particles coarser than this sieve require special clearances or a different type of paddle to permit the mixer to operate freely and to avoid damage to the paddle and bowl. The sequence of mixing shall be in accordance with the applicable provisions of Practice C 305 . Determine the flow of the mortar in accordance with the applicable provisions of Test Method C 1437, and use sufficient mixing water to produce a flow of 110 6 5 %. 8.4 Concrete—Mix concrete in a suitable laboratory mixer in accordance with the applicable provisions of Practice C 192/C 192M . Determine the slump of the concrete using Test Method C 143/C 143M , and use sufficient mixing water to produce a slump of 3.5 6 1 ⁄ 2 in. [90 6 15 mm]. tải về 128.58 Kb. Chia sẻ với bạn bè của bạn:
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