6.3.2 Before incorporating in concrete, prepare the aggregate to ensure a difinite and uniform condition of moisture. determine the weight of aggregate to be used in the batch by one of the following procedures:
6.3.2.1 determine the mass of low-absorption aggregates (absorption less than 1.0%) in the room-dry condition with allowance made for the amount of water that will be absorbed from the unset concrete (Note 9).this procedure is particularly useful for coarse aggregate which must be batched as individual sizes; because of the danger of segregation it can be used for fine aggregate only when the fine aggregate is separated into individual size fractions.
NOTE 9 when using aggregates with low absorption in room-dry condition the amount of water that will be absorbed by the aggregates before the concrete sets may be assumed to be 80% of the difference between the 24-h absorption of the aggregates determined by test methods C 127 or C 128,and the amount of water in the pores of the aggregates in their room-dry state, as determined by test method C 566.
6.3.2.2 individual size fractions of aggregate may be weighed separately, recombined into a tared container in the amounts required for the batch, and immersed in water for 24 h prior to use. after immersion the excess water is decanted and the combined weight of aggregate and mixing water determined. allowance shall be made foe the amount of water absorbed by the aggregate. the moisture content of the aggregates may be determined in accordance with test methods C 70 and C 566.
6.3.2.3 the aggregate may be brought to and maintained in a saturated condition, with surface moisture contained in sufficiently small amounts to preclude loss by draining at least 24 h prior to use. when this method is used, the moisture content of the aggregate must by determined to permit calculation of proper quantities of the damp aggregate. the quantity of surface moisture present must be counted as a part of the required amount of mixing water.surface moisture in fine aggregate may by determined in accordance with Test methods C 70 and C 566, making due allowance for the amount of water absorbed.the method outlined here (moisture content slightly exceeding absorption) is particularly useful for fine aggregate. It is used less frequently for coarse aggregate because of the difficulty of accurately determining the moisture content, but if used, each size fraction must be handled separately to ensure that the proper grading is obtained.
6.3.2.4 aggregates, fine or coarse, may be brought to and maintained in a saturated surface-dry condition until batched for use. this method is used primarily to prepare material for batches not exceeding 1/4 ft (0.007 m) in volume.care must be taken to prevent drying during weighing and use.
6.4 Lightweight aggregates the procedures for specific gravity, absorption. and preparation of aggregates mentioned in this practice pertain to materials with normal absorption values. lightweight
6.3.2 Before incorporating in concrete, prepare the aggregate to ensure a difinite and uniform condition of moisture. determine the weight of aggregate to be used in the batch by one of the following procedures:
6.3.2.1 determine the mass of low-absorption aggregates (absorption less than 1.0%) in the room-dry condition with allowance made for the amount of water that will be absorbed from the unset concrete (Note 9).this procedure is particularly useful for coarse aggregate which must be batched as individual sizes; because of the danger of segregation it can be used for fine aggregate only when the fine aggregate is separated into individual size fractions.
NOTE 9 when using aggregates with low absorption in room-dry condition the amount of water that will be absorbed by the aggregates before the concrete sets may be assumed to be 80% of the difference between the 24-h absorption of the aggregates determined by test methods C 127 or C 128,and the amount of water in the pores of the aggregates in their room-dry state, as determined by test method C 566.
6.3.2.2 individual size fractions of aggregate may be weighed separately, recombined into a tared container in the amounts required for the batch, and immersed in water for 24 h prior to use. after immersion the excess water is decanted and the combined weight of aggregate and mixing water determined. allowance shall be made foe the amount of water absorbed by the aggregate. the moisture content of the aggregates may be determined in accordance with test methods C 70 and C 566.
6.3.2.3 the aggregate may be brought to and maintained in a saturated condition, with surface moisture contained in sufficiently small amounts to preclude loss by draining at least 24 h prior to use. when this method is used, the moisture content of the aggregate must by determined to permit calculation of proper quantities of the damp aggregate. the quantity of surface moisture present must be counted as a part of the required amount of mixing water.surface moisture in fine aggregate may by determined in accordance with Test methods C 70 and C 566, making due allowance for the amount of water absorbed.the method outlined here (moisture content slightly exceeding absorption) is particularly useful for fine aggregate. It is used less frequently for coarse aggregate because of the difficulty of accurately determining the moisture content, but if used, each size fraction must be handled separately to ensure that the proper grading is obtained.
6.3.2.4 aggregates, fine or coarse, may be brought to and maintained in a saturated surface-dry condition until batched for use. this method is used primarily to prepare material for batches not exceeding 1/4 ft (0.007 m) in volume.care must be taken to prevent drying during weighing and use.
6.4 Lightweight aggregates the procedures for specific gravity, absorption. and preparation of aggregates mentioned in this practice pertain to materials with normal absorption values. lightweight
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