A Sustainable Approach for the Geopolymerization of Natural Iron-Rich Aluminosilicate Materials

Abstract

Two iron-rich clayey materials (L1 and L2, with the main difference being the level of iron accumulation) have been studied for their suitability as solid precursors for inorganic polymer composites. L1, with the lower iron content, was calcined at 700°C for 4 h and used as replacement, in the range of 15-35 wt%, for both raw laterites in the formulations of geopolymeric composites. The different mixtures were activated with a highly concentrated alkaline solution containing sodium hydroxide and sodium silicate. River sand with semi-crystalline structure was added to form semi-dry pastes which were pressed to appropriate shape. X-ray diffraction, Infrared spectroscopy, Scanning Electron Microscopy and Mercury Intrusion Porosimetry results demonstrated the effectiveness of the calcined fraction of L1 to act as nucleation sites and extend the geopolymerization to the matrix composites. A highly compact matrix with low porosity and good stability in water, together with a strength comparable to that of standard concretes was obtained allowing for conclusions to be made on the quality of laterites as promising solid precursor for sustainable, environmentally-friendly, and cost-efficient structural materials.

Physicochemical Characterization of Pulverized Phyllite Rock for Geopolymer Resin Synthesis

“…The higher kaolinite content can explain the overall superior performance of the CP in comparison to the WP geopolymer pastes despite the presence of more impurities (higher Fe 2 O 3 and TiO 2 content in the form of goethite and rutile). Previous studies indicate that iron does interfere in the strength development of geopolymer 13,14 . However, it is more likely that other factors such as particle size and the mineralogical form of the iron play a more critical role in their reactivity 13,14 .…”

“…Previous studies indicate that iron does interfere in the strength development of geopolymer 13,14 . However, it is more likely that other factors such as particle size and the mineralogical form of the iron play a more critical role in their reactivity 13,14 . When viewing the geopolymers synthesized with 75% of CP, only the use of the calcined for 6 h (CP-6) resulted in a compressive strength higher than that of SG (Figure 4b).…”

Inorganic polymers made of fayalite slag: On the microstructure and behavior of Fe

“…However, a significant proportion of the Fe 2+ in augite reacted with the alkali solution to form new ferric sites with Mössbauer parameters that were attributed to distorted tetrahedral or five‐fold coordinated sites. Obonyo et al studied the suitability of 2 partially amorphous Fe‐rich laterites as precursors for IPs. Different compositions including up to 35 wt% calcined laterite additions (for promoting reactivity) and river sand were prepared.…”

The Potential of Laterite Soils Deposit South Sulawesi as a Precursor for Na-Poly (Ferro-Sialate) Geopolymers

“…Several studies followed the utilization of aluminosilicates minerals rich with Fe in the production of geopolymers [8,27].…”