Lower‑carbon concrete technologies are changing the chemical environment inside concrete and opening the door for reinforcement materials that previously could not be used.

Aluminium, which is normally incompatible with high‑pH Portland cement concrete, becomes a promising option when combined with modern binder systems.

Traditional Portland‑cement concrete has a pH above 13, leading to rapid corrosion of aluminium and restricting its structural use. In contrast, emerging binder systems that include calcined clays and volcanic pozzolans create a lower‑pH environment, making aluminium reinforcement feasible in these concrete mixes.

In this paper, we will present results from both laboratory work and field exposure at Hydro Karmøy. Twelve concrete elements with aluminium reinforcement have been installed in three marine exposure zones: submerged, tidal and atmospheric. The elements represent different binder types, two concrete strength classes and three aluminium alloys, including one made from post‑consumer scrap. This setup allows us to compare how both alloy selection and binder chemistry affect corrosion behavior.

Corrosion performance has been evaluated through electrochemical measurements, galvanic coupling and long‑term exposure at the test site. Early results show very low corrosion rates for aluminium in the low‑pH concretes used, and only minor galvanic interaction with A4/316 stainless steel, even when fully submerged. These findings indicate that aluminium performs well in these concrete formulations.

Using aluminium reinforcement also reduces, or in some cases removes, the need for concrete cover. This can produce slimmer elements and reduce material use. Combined with low‑CO₂ binders, this leads to a significant reduction in embodied carbon. It also expands design possibilities, for example allowing exposed or hybrid structural–aesthetic solutions.

Taken together, the results show that aluminium has strong potential to enable durable, low‑carbon concrete systems and to open new application areas for aluminium alloys in construction.

Dr. Malgorzata Chojak Halseid