Over years of detailed research and weathering tests, iron oxide pigments have proven their reliability across a wide range of concrete construction materials. However, their use in new-generation concrete formulations demands a strong understanding of construction chemistry and the interactions between binders, additives, and pigments.
As innovative concrete technologies gain momentum, the influence of pigments on performance and appearance has become increasingly important. According to Oliver Fleschentraeger, Technical Service for Construction Materials at LANXESS Inorganic Pigments, this shift has placed pigments firmly in the spotlight of material development.
Supporting Innovation Through Collaborative Research
To address these evolving challenges, LANXESS actively supports the development of new concrete technologies. The company works closely with customers, additive manufacturers, and universities to optimise pigment use and processing.
This work is backed by LANXESS’s application engineering laboratories and a dedicated technical centre for pigment applications. Together, these facilities enable in-depth testing of pigment properties and their direct impact on concrete performance.
Achieving Uniform Colour in Self-Compacting Concrete
Self-compacting concrete (SCC) has become the preferred material for complex reinforced structures and high-end architectural applications. Its excellent flowability and self-ventilation allow the creation of smooth, pore-free, and visually consistent surfaces.
However, some users have reported uneven coloration when using inorganic pigments. LANXESS investigations identified the cause as the plasticizer polycarboxylate ether (PCE), commonly used to improve SCC flow properties.
Higher dosages of PCE and water were found to disrupt the uniform distribution of iron oxide pigments. This occurs due to surface-enriched ettringite phases, which lead to visible colour deviations. Following extensive laboratory studies, LANXESS experts, together with external institutes, successfully optimised SCC formulations to restore consistent pigmentation.
Geopolymers and Cement-Reduced Binders: A Pigment Challenge
Another key research focus at LANXESS involves cement-reduced clinker systems, developed using alternative binders that enable lower CO₂ emissions. These include alkali-activated materials and geopolymers such as metakaolin and clay.
Unlike alkali-activated materials, which form charged calcium silicate hydrate (CSH) phases, geopolymers create neutral, network-like structures. As a result, iron oxide pigments cannot form durable bonds within the geopolymer matrix. Instead, pigments remain loosely embedded, reducing long-term colour stability.
To address this limitation, LANXESS pigment specialists are currently working with industry partners and research institutes to develop solutions that ensure durable pigment fixation in geopolymer-based concretes.
3D-Printed Concrete: Adding Colour to Additive Manufacturing
Colour is also gaining importance in 3D-printed concrete, a rapidly evolving segment within the construction industry. At present, most applications rely on standard grey concrete, largely due to limited experience with pigment behaviour in additive manufacturing processes.
Since 3D concrete formulations often include novel additives, iron oxide pigments interact differently with the system. Recognising this gap, LANXESS partnered with TU Dresden to assess the suitability of its pigments for layer-by-layer concrete printing.
The completed first research phase evaluated flow behaviour, curing, setting time, and compressive strength using standard DIN-compliant 3D concrete formulations. Testing with LANXESS red iron oxide pigments, produced via the proprietary Laux process, showed excellent colour consistency, development, and homogeneity.
According to Fleschentraeger, these results confirm the pigments’ strong potential for high-resolution coloured 3D concrete applications.
