Title:
Pore Structure Characterization and Environmental Assessment of Ground Volcanic Pumice-Based Alkali-Activated Concrete
Author(s):
Mohammed Ibrahim, Ashraf A. Bahraq, Babatunde Abiodun Salami, Luai Mohammed Alhems, Syed Rizwanullah Hussaini, Muhammad Nasir, Adeshina Adewale Adewumi
Publication:
IJCSM
Volume:
19
Issue:
Appears on pages(s):
Keywords:
Ground volcanic pumice, Nanosilica, Alkali-activated concrete, 1H proton NMR relaxometry, Pore structure, Chloride diffusion, Chloride-induced corrosion, LCA study
DOI:
10.1186/s40069-025-00791-3
Date:
11/30/2025
Abstract:
The impact of pore structure and its connectivity in ground volcanic pumice (GVP) and nano-silica (nSi)-based AAB on the chloride diffusion leading to corrosion of reinforcing steel for a period of up to 2.5 years was investigated in this study. 1H proton NMR relaxometry was employed as an innovative method to examine the pore structure and connectivity in alkali-activated concrete (AAC), in conjunction with the assessment of bulk chloride diffusion. Alkali-activated GVP with marginal quantities of nSi outperformed similar grade conventional OPC concrete when exposed to bulk diffusion in accordance with ASTM C1556. There was nearly 80–90% reduction in chloride diffusivity in 5.0% and 7.5% nSi mixes and 60% increase in compressive strength. The contour maps showed that nSi incorporation greater than or equal to 5.0% significantly lowered porosity, enabled poor pore connectivity and minimized chloride diffusion, resulting in enhanced protection against chloride-induced corrosion of steel rebar in the AAC. It was revealed that the remarkable resistance of nSi-modified GVP-AAC to the aggressive environment was attributed to the better polymerization and physical influence enhanced the binder structure. The environmental assessment results showed that GVP-based alkali-activated mixes reduced CO2 emissions by 53% to 60% compared to the OPC-based mix, demonstrating their strong potential for lowering the carbon footprint of concrete.