Abstract
This microscopic characteristics of basalt bars after exposure to alkaline solutions and pullout performance of steel and basalt rebars embedded in conventional and alkali-activated concrete were studied. The overarching goal is to assess the potential of basalt rebars as an alternative to conventional steel reinforcement in alkali activated concrete elements. To understand their durability in alkaline environments, especially within alkali-activated concrete (AAC), steel and basalt rebars were subjected to an accelerated exposure test in high-pH simulated concrete pore solutions, for 24hrs. This aimed to replicate the aggressive internal environment typically found in AAC and mixes with supplementary cementitious materials. Post-exposure microscopic inspection revealed morphological changes, but the changes were limited to the adhesives and did not influence the basalt fibre bundles. Pullout tests were conducted in reference to BS EN 1881:2006, using a 50:50 blend of CEM I and GGBS. AAC mixes used 6% and 8% alkali dosages. Both steel and basalt rebars exceeded the 75kN standard threshold. Steel rebars reached up to 115kN, while basalt rebars recorded 100–120kN. Predominant failure mode was midsection concrete splitting. Slightly higher bond strength in basalt-reinforced AAC samples may result from interface roughening caused by the initial high alkaline exposure(i.e., to activator solution). These findings highlight the viability of basalt rebars as a low-carbon, structurally reliable alternative to steel in AAC systems.
Keywords
pullout test, alkali-activated concrete, microstructure, basalt rebar, sustainable reinforcement, bond strength.
DOI
10.5703/1288284318163
Recommended Citation
ALEX, ANSU MARY; Nanukuttan, Sreejith; McCartney, Adeline; Soutsos, Marios; and McPolin, Daniel, "Surface Morphology, Bond Strength and Failure Behaviour of Steel vs Basalt Rebars in Alkali Activated Concrete" (2025). International Conference on Durability of Concrete Structures. 3.
https://docs.lib.purdue.edu/icdcs/2025/act/3
Surface Morphology, Bond Strength and Failure Behaviour of Steel vs Basalt Rebars in Alkali Activated Concrete
This microscopic characteristics of basalt bars after exposure to alkaline solutions and pullout performance of steel and basalt rebars embedded in conventional and alkali-activated concrete were studied. The overarching goal is to assess the potential of basalt rebars as an alternative to conventional steel reinforcement in alkali activated concrete elements. To understand their durability in alkaline environments, especially within alkali-activated concrete (AAC), steel and basalt rebars were subjected to an accelerated exposure test in high-pH simulated concrete pore solutions, for 24hrs. This aimed to replicate the aggressive internal environment typically found in AAC and mixes with supplementary cementitious materials. Post-exposure microscopic inspection revealed morphological changes, but the changes were limited to the adhesives and did not influence the basalt fibre bundles. Pullout tests were conducted in reference to BS EN 1881:2006, using a 50:50 blend of CEM I and GGBS. AAC mixes used 6% and 8% alkali dosages. Both steel and basalt rebars exceeded the 75kN standard threshold. Steel rebars reached up to 115kN, while basalt rebars recorded 100–120kN. Predominant failure mode was midsection concrete splitting. Slightly higher bond strength in basalt-reinforced AAC samples may result from interface roughening caused by the initial high alkaline exposure(i.e., to activator solution). These findings highlight the viability of basalt rebars as a low-carbon, structurally reliable alternative to steel in AAC systems.
