Rheological Characteristics of Wet-Mix Shotcrete Mixtures with Crushed Aggregates and Mineral Admixtures

In this study, implications of various mineral admixtures such as fly ash, silica fume, metakaolin, and Ground Granulated Blast Furnace Slag (GGBFS) for the rheological properties of fresh wet-mix shotcrete incorporating crushed aggregates are quantitatively assessed. Laboratory testing was performed using an IBB rheometer, which is proven to suitably measure the Bingham parameters of fresh concrete mixtures. Technical tips to improve the pumpability and shootability are also proposed in terms of the type and replacement level of mineral admixtures based on the results of rheological characterization. The findings from a series of laboratory tests include: (1) incorporating higher dosages of fly ash and silica fume led to an enhancement of both pumpability and shootability for wet-mix shotcrete mixtures; (2) the use of metakaolin and GGBFS was only effective in improving the pumpability, particularly when lower dosages were employed; and (3) a build-up thickness of approximately 240 mm to 390 mm could be achieved by varying the type and replacement level of mineral admixtures.