Title:
Testing and Consolidation of Test Samples for SWC and FR-SWC
Author(s):
Kamal Khayat
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
3/28/2021
Abstract:
The use of fibers to enhance the performance of superworkable concrete can hinder workability necessitating further mechanical consolidation that can lead to segregation. This paper evaluates the effect of mechanical consolidation on segregation, surface quality, and mechanical properties of fiber-reinforced superworkable concrete (FR-SWC) in an effort to recommend a protocol that can be employed for the preparation of test samples of FR-SWC. Mixtures prepared using polypropylene and steel fibers incorporated at a volume of 0.5% were tested. With each fiber type, test parameters involved the incorporation or omission of viscosity-modifying admixture and addition of high-range water reducer to assure a slump flow of 450 mm (17.7 in.) or 550 mm (21.7 in.). Test cylinders were cast in one layer and underwent different degrees of mechanical consolidation using a 10 mm (0.39 in.) steel rod. Vibrating table was also used to induce high consolidation effort during 20 and 25 seconds. Image analysis was carried out on longitudinally saw-cut surfaces of the concrete cylinders. Test results indicate that rodding enabled the reduction of honeycombing but did not affect mechanical properties and segregation. The use of vibration consolidation enhanced mechanical properties and surface quality but led to considerable increase in segregation, unless the concrete is highly stable. Casting test samples in one lift and consolidating them with 20 strikes of rodding can provide adequate consolidation energy to enhance mechanical properties and surface properties without segregation.