Effect of Rate of Lifting of Slump Cone on Indicated Slump of Concrete.
Abstract
Tests were conducted using a mechanical device for lifting a slump cone at various lifting rates. Four sets of randomly chosen lift times up to and including 10 sec were used to test four batches each of nominal 1-, 3-, and 6-in.-slump concretes. Three batches of nominal 5-1/2-in.-slump concrete were tested using sequence lift times of three permutations of 1, 5, and 10 sec. All mixtures were proportioned using 1-1/2-in. maximum-size limestone aggregate, 6.2 bags of cement per cubic yard, and 3 oz of molasses as a retarder. The results showed that lapsed time (i.e., time after water was added to the mixture) had more effect on the measured slump of the 1-, 3-, and 6-in.-slump concrete than did randomized time of cone lift. The results of sequence lift time tests showed a slightly significant difference in slump due to time of cone lift, the difference being between the slump occurring for a 1-sec lift time and that occurring for a 5-sec lift time. For nominal 5-1/2-in.-slump concrete, the slump test should be performed as soon as possible after water is added to the mixture using a cone lift time of 5 plus or minus 3 sec. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1971
- Accession Number
- AD0727679
Entities
People
- Hugh K. Wilson
- Richard L. Stowe