Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

Abstract

The use of bulk solid-waste iron tailing (IOT), red mud (RM), and oyster shells to prepare cemented paste backfill (CPB) can effectively solve the ecological problems caused by industrial solid waste storage and improve the utilization rate of such materials. In this study, a new type of CPB was prepared by partially replacing slag with RM, with calcined oyster shell (COS) as the alkaline activator and IOT as aggregate. The central composite design (CCD) method was used to design experiments to predict the effects of the COS dosage, RM substitution rate, solid mass, and aggregate–binder ratio using 28-dUCS, slump, and the cost of CPB. In this way, a regression model was established. The quantum genetic algorithm (QGA) was used to optimize the regression model, and X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) microscopic tests are performed on CPB samples of different ages with the optimal mix ratio. The results showed that COS is a highly active alkaline substance that provides an alkaline environment for polymerization reactions. In the alkaline medium, the hematite and goethite in RM and quartz in IOT gradually dissolved and participated in the process of polymerization. The main polymerization products of the CPB samples are calcium–silicate–hydrogel (C–S–H), calcium–aluminosilicate–hydrogel (C–A–S–H), and aluminosilicate crystals such as quartz, albite, and foshagite. These products are intertwined and filled in the internal pores of the CPB, enabling the pore contents to decrease and the interiors of the CPB samples to gradually connect into a whole. In this way, the compressive strength is increased.

Study of the properties of red mud-waste incineration ash composites

“…10 (f) reveals that the Ca element content is 21% and the Al element content is 5.76%, suggesting that when calcium hydroxide is activated, the silicaaluminum precursor material dissolves in an alkaline solution, resulting in the formation of silica-aluminum molecules. Additionally, the Al partially replaces Si and enters the C-S-H gel, leading to the formation of the hydrated silica-aluminum acid calcium [53] , thus generating a C-A-S-H gel. In addition, the iron content at point D was 14.69%, indicating that the red mud dissolved more fully with increasing age of conservation.…”

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

“…Uniaxial compressive strength (UCS) is a commonly used mechanical index, which directly reflects the hardening process of CPB [45][46][47][48]. In a UCS test, the CPB can generate, propagate, locate, and accumulate cracks, resulting in a series of stress-strain behaviors [49][50][51]. The strength and deformation behavior are the criteria used to measure the fracture evolution or failure of CPB, and thus, they have been the main focus of CPB research to date.…”

Synthesis and Performance Evaluation of Nano-Calcium Carbonate-Modified Geopolymers Incorporating Fly Ash and Manganese Slag: A Comprehensive Investigative Study

“…In contrast to conventional silicate-based cements, geopolymers present a multifaceted spectrum of enhanced attributes encompassing mechanical potency, resistance to corrosion, effective thermal insulation, and adept sequestration of heavy metal ions. These qualities render them propitious candidates for application spanning diverse domains, ranging from architectural engineering to waste management, aerospace technology, and defense systems [6]. Kassym Yelemessov researched the prospects of the application of building structures made of polymer concrete composites on the basis of strength analysis [7].…”