Optimization of Self Consolidating Concrete for Slip-form pavementPublic Deposited
The concrete currently used in the slip-form paving process is a low slump concrete that requires both internal and external vibration in order to achieve satisfactory compaction. The use of vibrator fingers for the internal vibration often leads to trails on the surface of the pavement and to segregation around the trails, which cause durability issues. The objective of this project is to overcome these problems by designing a concrete that would not require the use of internal vibrators. The concrete should be workable enough for machine placement, compactable with a minimum of energy and hold its shape for the slip-form process. Various mix designs based on the concept of Self-Consolidated Concrete were studied, so as to have some flowability and some compactibility, the challenge being to make them shape-stable. Different fine materials were added in the mix design to make the concrete hold its shape. The fine materials used were different types of clays, fly ash and magnesium oxide. The addition of polypropylene fibers was also studied. The flowability of the concrete was evaluated by using the drop table test, while the shape stability was measured by the green strength. A mini-paver was developed in collaboration with Iowa State University so as to simulate the slip-form paving process and was used to test selected mixes. The fresh and hardened state properties of the selected mixes are examined in this paper.
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