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Behind the Printed Layer: Alexander Nikolov and the Science of Better Binders

A printed concrete object begins long before the nozzle moves. It begins with decisions about powders, water, chemical reactions and the time available to shape a material. A compelling design needs a mixture that can be processed consistently and assessed against the demands of its intended use.

Alexander Nikolov brings materials chemistry and geopolymer expertise to CONCREEF’s technical team. His value lies in connecting the composition of a material with how it behaves, helping the team ask better questions about binders and plan meaningful tests.

A research foundation in construction materials

Alexander holds a PhD from the University of Architecture, Civil Engineering and Geodesy in Sofia. The Institute of Mineralogy and Crystallography at the Bulgarian Academy of Sciences lists him as an associate professor. His work spans natural zeolites, geopolymers and the use of industrial by-products in alternative construction materials. These are areas where understanding the raw material is essential to choosing a viable formulation. Institutional profile.

At CONCREEF, this expertise complements architectural design, machine operation and software automation. It brings a scientific perspective to the material itself: what is reactive, which ingredients change the hardening process, and which measurements can distinguish a promising mixture from a repeatable one.

The same mineral can produce very different materials

In a 2017 study, Nikolov and co-authors investigated geopolymers made with natural clinoptilolite from Bulgaria’s Beli Plast deposit. They compared different alkaline activators and examined the resulting materials using mechanical tests, X-ray diffraction, thermal analysis and microscopy. The activators produced different degrees of dissolution and different structures. The room-temperature-cured materials had relatively low compressive strength, while coatings showed good adhesion to concrete. Nikolov, Rostovsky and Nugteren, 2017.

That distinction matters. A material suitable for an adherent coating is not automatically suitable for a load-bearing component. A familiar ingredient name does not define a product’s performance. Composition, processing and intended application must be considered together.

Later research explored calcination and aluminate activation as ways to optimize clinoptilolite-based geopolymers. This is a useful example of the work behind material development: changing the precursor or activator, then checking what actually improves. Nikolov, Nugteren and Rostovsky, 2020.

Why this matters for 3D concrete printing

For CONCREEF, the practical opportunity is to connect material selection with a controlled development process. A printed mixture must pass through equipment and retain the intended shape after deposition. A hardened specimen’s strength alone cannot establish whether a mixture can be printed reliably.

Our interpretation of this research is a development sequence with four connected questions:

  • What is in the raw material? Establish composition, particle characteristics and the consistency of the supply before treating one batch as representative of another.
  • How does the mixture change with time? Track fresh behavior and setting alongside the intended mixing and printing sequence.
  • What happens between layers? Assess the deposited geometry and the effect of pauses and interfaces, rather than relying only on cast specimens.
  • How does the finished material perform in use? Select tests for the actual component and exposure, including moisture, dimensional stability and mechanical demands.

These are proposed development priorities, not a claim that a particular CONCREEF geopolymer formulation has already passed them. Alexander’s research provides relevant expertise for deciding what to investigate and how to interpret the results.

Performance has more than one dimension

A 2025 paper co-authored by Nikolov investigated foamed geopolymers based on fayalite slag and metakaolin. Changing the water-to-solid ratio and adding an air-entraining admixture affected pore structure, density and strength. The researchers also prepared larger specimens for thermal-conductivity measurements and a preliminary flame-exposure test. They identified further work on leaching, scale-up and fire performance. Nikolov et al., 2025.

The relevance is the method of balancing properties. A lightweight insulating material and a dense outdoor component solve different problems. Evidence from one cannot simply be transferred to the other, and a preliminary fire experiment does not certify a finished building product.

Better questions lead to better development decisions

For designers and project partners, CONCREEF’s combination of digital fabrication and materials expertise creates a useful starting point: discuss the desired form together with the conditions the material must withstand. That makes the brief more specific and the next experiment more informative.

Alexander’s contribution strengthens that conversation. It connects design ambition with the chemistry, characterization and testing needed to evaluate new material possibilities responsibly.

Meet the CONCREEF team or discuss a material and design brief.

CONCREEF editorial article based on the linked research and professional background. Research credit belongs to the original authors; this article is not presented as written or endorsed by Alexander Nikolov. Published experimental results are not CONCREEF product specifications.