A study for suitability of local quarry dust materials for replacement of aggregate in an ultra-high-performance geopolymer concrete

As part of a research project to develop a prototype, ultra-high-performance, low impact, precast , concrete sandwich panel for the retrofit cladding of existing buildings, a geopolymer concrete material using industrial by-product and waste materials as a more sustainable alternative to traditional Portland cement concrete has been developed. In order to assess the suitability of three locally available quarry dust materials-basalt, greywacke and granite-as a virgin aggregate replacement, a series of tests using an electron microscope, x-ray diffractometer, x-ray fluorescence and laser diffraction spectrometer were carried out to establish the particle size, shape and elemental composition of the materials. A mix previously developed for the production of a prototype precast geopolymer concrete sandwich panel was used as a control for the comparative performance of the quarry dust based mixes. The control mix contained beach pebble, silica sand and quartz flour aggregates with an alkali activated blast furnace slag and silica fume geopolymer binder. Samples of all four mixes were tested for flow, setting time and compressive strength with all of the quarry dust materials achieving the required flow for a self-compacting mix, setting times in the region of 30 minutes and 7 day compressive strengths in excess of 80MPa.