Preparation and properties of sintering red mud unburned road brick using orthogonal experiments

As the major solid waste, Sintering Red Mud (SRM) comes from the process of sintering alumina production. In order to study the application of SRM-URB in road engineering, this paper utilized cement-fly ash-lime to stabilize SRM and adopted normalized orthogonal table of L9 (3(4)) in the orthogonal experiment design, thus acquiring the optimum mix proportion of SRM-URB. It also evaluated the properties of optimal SRM-URB including physical property, shrinkage property, frost resistance property and did research on influences of curing condition, cement content and fly ash content on unconfined compressive strength (UCS) of SRM-URB under 7-day and 28-day curing conditions. Experimental results showed that the prepared SRM-URB with optimal proportion had good road performance and compressive strength under 28-day standard curing condition was greater than 19 MPa, which significantly influenced the UCS. The energy dispersive X-ray spectroscopy (EDS) and the X-ray diffraction (XRD) results showed that SRM contained many hydrated active minerals. The Scanning Electron Microscope(SEM) results showed that C-S-H gel and ettringite came into being, which produced particles and form network structure thus enhancing strength and compactness of SRM-URB. The study shows that SRM is suitable for becoming the raw material of unburned road bricks, whose application in road engineering would be an effective strategy to ease the environmental burden. (C) 2019 Elsevier Ltd. All rights reserved.