Title:
Effect of Carbonation on Mechanical Properties and Microstructure of One-Part- Geopolymer based on Thermo-Mechanical-Synthesis Sediments Fy Ash Mix
Author(s):
Elie Mahfoud, Khadim Ndiaye, Walid Maherzi, Salima Aggoun, Nor-Edine Abriak, Mahfoud Benzerzour
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
616-629
Keywords:
one-part-geopolymer, sediments, fly ash, durability, carbonation, mechanical properties
DOI:
10.14359/51741016
Date:
6/14/2024
Abstract:
This study aims to determine the carbonation effect on mechanical properties and microstructure of a one-part-geopolymer based on a thermo-mechanical-synthesis sediments-fly ash mixture. Four mixtures containing 0, 15, 30, and 50% sediments and optimized in terms of mechanical performance were exposed to accelerated (3% CO2) and natural carbonation. Carbonation depth and pH of mortars (4x4x16 cm2) were measured according to CO2 exposition time. Carbonation products were identified by XRD on pastes. The carbonation effect on geopolymer properties was studied by SEM-EDS observations and the mechanical strength investigation. Carbonation depth was between 4 and 6 mm with difficulty in detecting areas of partial carbonation using phenolphthalein. Nahcolite (sodium bicarbonate) is mainly the accelerated carbonation product leading to a pH decrease but still above the steels depassivation threshold. Secondary products are natron (sodium carbonate) and calcite which appear with sediment incorporation. Carbonation products with binding properties have closed pores and cracks, and consequently improved mechanical performance.