科研之友
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摘要
The setting time of concrete as measured by ASTM C403-08 is determined from the penetration resistance of mortar extracted from concrete by removing coarse aggregates larger than the 4.75mm (#4) sieve. Tests by the authors and others have shown a difference in penetration resistance obtained from mortars extracted from concrete compared with penetration resistance of mortar intentionally mixed to represent the mortar fraction of the concrete of interest, as is noted qualitatively in ASTM C403. The authors report this difference quantitatively, having observed or discovered in the literature prepared mortars with an initial setting time up to 6 %-16 % greater than that of sieved mortar, and final setting time that is up to 3 %-16 % greater than that of sieved mortar. In general, these differences are 1 to 3 times greater than the single operator precision for acceptable range of test results, and are thus significant in the context of ASTM C403.
- 出版日期2015-7
