# Assessment of Physical Properties and Potential Elemental Leaching from Bauxite Tailing-Based Alkali-Activated Materials

## TL;DR

This study explores using bauxite tailings to create strong, durable alkali-activated materials with low water absorption and good acid resistance.

## Contribution

The novelty lies in using Amazon region bauxite washing clay as a precursor for alkali-activated materials and evaluating their physical and elemental leaching properties.

## Key findings

- The synthesized materials showed low water absorption (18.61%) and high compressive strength (25.83 MPa).
- The material released Al, Si, and Na during acid leaching, which are essential for geopolymer formation.
- Bauxite washing clay is a suitable precursor due to its high aluminum and silica content.

## Abstract

Alkali-activated materials (AAMs) are emerging materials
with enhanced
properties, including high compressive strength, low shrinkage, adjustable
curing rates, resistance to acids and fire, and low thermal conductivity.
These materials are synthesized by reacting aluminosilicate-rich precursors
with highly alkaline solutions. Given these advantageous characteristics,
this study investigates the synthesis of AAMs using bauxite washing
clay from the Amazon region. Specimens were prepared with bauxite
washing clay and a 1.3 M NaOH solution. The raw material was characterized
by using X-ray diffraction (XRD), thermal analysis (TGA-DSC), Fourier
transform infrared spectroscopy, and X-ray fluorescence. The specimens
were further analyzed by XRD and tested for compressive strength,
water absorption, apparent porosity, and acid leaching using HNO3. The bauxite washing clay sample primarily comprises aluminum-
and silica-rich minerals such as kaolinite and gibbsite, making it
a suitable precursor for alkali activation. The synthesized specimens
demonstrated low water absorption (18.61% ± 0.25) and significant
mechanical strength (25.83 MPa ± 1.33). Regarding the potential
release of metals and metalloids, the highest concentrations were
observed for Al, Si, and Na - key elements in geopolymer formation.