Using fly ash, clay, and fibers for simultaneous improvement of concrete green strength and consolidatability for slip-form pavement

This paper presents a procedure to find the optimal balance between the consolidation properties and shape stability of fresh concrete mixtures to achieve a self-consolidating concrete applicable for the slip-form paving process. The investigations started with a conventional slip-form paving concrete mixture. Various types and amounts of supplementary cementitious materials (fly ash), admixtures (water reducers), and additives (clays, magnesium oxide, and fibers) were then gradually applied to modify flowability and maintain sufficient green strength. This approach has led to a successful mix design-the concrete mixture can be consolidated without internal or external vibration and also maintains its slab shape after the slip-form paving process. In the present paper, the step-by-step mix design approach is described, and the effects of admixtures and additives on concrete flowability and shape stability are explained.