Ternary Gypsum–Cement–Pozzolanic Compositions for 3D Printing: Mix Design, Rheology and Long-Term Performance Genadijs Sahmenko, Girts Bumanis, Maris Sinka, Peteris Slosbergs, Alise Sapata, Diana Bajare, Vjaceslavs Lapkovskis Infrastructures, 2026 Ternary gypsum–cement–pozzolan (GCP) binders represent a promising low-carbon alternative to traditional Portland cement-based systems for additive 3D printing (3DP). This study presents a systematic three-stage experimental framework for the development of printable and durable GCP mixtures: (i) optimisation of gypsum–cement–metakaolin binder proportions based on a ternary diagram for 25 formulations, (ii) comparative evaluation of different pozzolanic additives and secondary gypsum sources alongside comprehensive durability testing, and (iii) adaptation of the optimised mixtures for 3DP, focusing on rheological properties. The optimal composition was determined with 55 wt% gypsum, 22.5 wt% Portland cement, and 22.5 wt% metakaolin, achieving a 28-day wet compressive strength of 36.2 MPa and a softening coefficient of 0.85. Successful integration of secondary gypsum sources was demonstrated. The GCP 3DP mixtures were developed with water/binder ratios of 0.38–0.45 and sand/binder ratios of 0.5–1.4, with an open time of 20–40 min. The mixtures exhibit pronounced thixotropic behaviour, characterised by increasing yield stress over time and relatively stable plastic viscosity. Printability tests confirmed the stable application of 29–39 layers before structural buckling. 3DP under laboratory conditions successfully demonstrated the feasibility of producing architectural and structural elements from sustainable GCP compositions.
Development of a Mineral Binder for Wood Wool Acoustic Panels with a Reduced Carbon Footprint Aleksandrs Korjakins, Genadijs Sahmenko, Ina Pundiene, Jolanta Pranckevicienė, Vjaceslavs Lapkovskis Materials, 2025 The construction industry’s reliance on Portland cement (PC) significantly contributes to global CO2 emissions, driving the search for sustainable binder alternatives. This study develops and evaluates novel mineral binder systems for wood wool acoustic panels with a reduced carbon footprint. Alternative binders, including calcium aluminate cement (CAC), magnesium oxychloride cement (MOC), and gypsum–cement–pozzolan (GCP) hybrids, were combined with additives such as metakaolin and liquid glass. Mechanical testing demonstrated that 20–30% metakaolin and liquid glass composites achieved flexural strengths of up to 2.65 MPa and densities above 490 kg/m3. The GCP system showed synergistic improvements in flexural and compressive strengths by nearly 50%, along with enhanced dimensional stability and water resistance. Life cycle assessment indicated substantial CO2 emission increases, particularly for the MOC and CAC formulations, compared to conventional Portland cement-based panels. The carbon footprint of the binder system consisting of GCP is approximately 5.644 kg of CO2 equivalent per functional unit compared to magnesium chloride binder systems, which reach up to 10.84 kg CO2 eq., and white Portland cement systems, which are around 6.19 kg CO2 eq. The three-component GCP binder system offers the best balance of mechanical performance and minimised environmental impact. Key raw material contributors to the ecological load are cement (various types), MgO, MgCl2, and metakaolin, highlighting the importance of optimising binder formulations to reduce carbon emissions. The GCP system, in particular, demonstrates unprecedented synergistic improvements in flexural and compressive strengths, dimensional stability, and water resistance while minimising CO2 emissions. Current work sets a new benchmark for sustainable building materials by offering an eco-innovative pathway towards low-carbon, high-performance wood wool acoustic panels, aligning with global decarbonisation goals.
A Short Review of Recent Innovations in Acoustic Materials and Panel Design: Emphasizing Wood Composites for Enhanced Performance and Sustainability Aleksandrs Korjakins, Genadijs Sahmenko, Vjaceslavs Lapkovskis Applied Sciences Switzerland, 2025 The aim of this study is to investigate the potential of wood composites as sustainable acoustic materials and to explore their integration with advanced manufacturing techniques for improved performance. Using a comprehensive review methodology, the paper analyzes recent innovations in wood composites, focusing on the combination with other sustainable materials such as expanded polystyrene (EPS) and natural fibers. The results show that wood composites can achieve sound absorption coefficients (α) of up to 0.9, with oak panels showing transmission losses of up to 11 dB. In addition, advanced designs, including biodegradable panels and lightweight honeycomb structures, significantly improve sound transmission loss, with an average sound transmission loss (TLeq) of up to 28.3 dB reported for composite panels made from waste tire rubber. In addition, the study highlights the environmental benefits achieved through the use of agricultural byproducts and industrial waste in the development of these materials, confirming the role of wood composites as a carbon-neutral alternative in the quest for green building solutions. This study provides valuable insights into the transformative potential of wood composites for sustainable acoustic applications.
Establishing Benchmark Properties for 3D-Printed Concrete: A Study of Printability, Strength, and Durability Alise Sapata, Māris Šinka, Genādijs Šahmenko, Lidija Korat Bensa, Lucija Hanžič, Katarina Šter, Sandris Ručevskis, Diāna Bajāre, Freek P. Bos Journal of Composites Science, 2025 This study investigates the fresh state and hardened state mechanical and durability properties of 3D-printed concrete. The mechanical tests focused on its anisotropic behavior in response to different load orientations. Compressive, flexural, and splitting tensile strengths were evaluated relative to the print layers orientation. Results showed that compressive strength varied significantly, achieving 85% of cast sample strength when the load was applied parallel to the print layers ([u] direction), 71% when the load was applied perpendicular to the print object’s side plane ([v] direction), while only reaching 59% when applied perpendicular to the top plane ([w] direction). Similar trends were observed for flexural strength, with average values reaching 75% of cast sample strength when the load was applied perpendicular to the print layers ([v.u] and [w.u] directions), but decreasing to 53% when the load was applied parallel to print layers ([u.w] direction), underscoring the weaknesses at interlayer interfaces. The splitting tensile strength remained relatively consistent across print orientations, reaching 90% of the cast sample strength. Durability assessment tests revealed that 3D-printed concrete exhibits reduced resistance to environmental factors, particularly at the layer interfaces where the cold joint was formed, which are prone to moisture penetration and crack formation. These findings contribute valuable insights into the mechanical and durability properties of 3D-printed concrete, emphasizing the importance of print orientation and interlayer bonding in its performance. This understanding helps guide the optimal use of 3D-printed elements in real-life applications by aligning load or exposure to environmental factors with the material’s strength and durability characteristics.
The Impact of Production Techniques on Pore Size Distribution in High-Strength Foam Concrete Slava Markin, Genadijs Sahmenko, Aleksandrs Korjakins, Viktor Mechtcherine Infrastructures, 2025 This study examined the impact of various foam concrete production techniques on pore size distribution and its water absorption properties. Techniques such as the use of a cavitation disintegrator and a turbulent mixer were employed to produce foam concrete. Six foam concrete compositions, with dry densities ranging from 820 to 1480 kg/m3 and compressive strength up to 47 MPa, were prepared. A novel method for digital image correlation was applied to analyse the pore size distribution within the foam concrete specimens. The manufactured foam concrete specimens’ porosity and water absorption indices were determined. The experimental results, including compression strength and water absorption, indicated that the production technique significantly affects the pore size distribution in foam concrete, impacting its mechanical and durability properties. Compressive strength was assessed at curing intervals of 7, 28, and 180 days. Cavitation technology was found to promote the formation of a finer porous structure in foam concrete, resulting in enhanced strength properties.
Collision Milling of Oil Shale Ash as Constituent Pretreatment in Concrete 3D Printing Lucija Hanžič, Mateja Štefančič, Katarina Šter, Vesna Zalar Serjun, Māris Šinka, Alise Sapata, Genādijs Šahmenko, Evaldas Šerelis, Baiba Migliniece, Lidija Korat Bensa Infrastructures, 2025 Concrete is an essential construction material, and infrastructures, such as bridges, tunnels, and power plants, consume large quantities of it. Future infrastructure demands and sustainability issues necessitate the adoption of non-conventional supplementary cementitious materials (SCMs). At the same time, global labor shortages are compelling the conservative construction sector to implement autonomous and digital fabrication methods, such as 3D printing. This paper thus investigates the feasibility of using oil shale ash (OSA) as an SCM in concrete suitable for 3D printing, and collision milling is examined as a possible ash pretreatment. OSA from four different sources was collected and analyzed for its physical, chemical, and mineralogical composition. Concrete formulations containing ash were tested for mechanical performance, and the two best-performing formulations were assessed for printability. It was found that ash extracted from flue gases by the novel integrated desulfurizer has the greatest potential as an SCM due to globular particles that contain β-calcium silicate. The 56-day compression strength of concrete containing this type of ash is ~60 MPa, the same as in the reference composition. Overall, collision milling is effective in reducing the size of particles larger than 10 μm but does not seem beneficial for ash extracted from flue gasses. However, milling bottom ash may unlock its potential as an SCM, with the optimal milling frequency being ~100 Hz.
Comparative Study on the Impact of Various Non-Metallic Fibres on High-Performance Concrete Properties Aleksandrs Korjakins, Girts Kolendo, Vitalijs Lusis, Laura Spure, Kaspars Bondars, Diana Bajare, Genadijs Sahmenko Journal of Composites Science, 2024 The performance of high-performance concrete has been enhanced in the present study by incorporating non-metallic fibres without altering the binder content. The impact of these fibres on high-performance concrete flexural and compression characteristics and the arrangement of fibres within the composite were systematically analysed. Unlike conventional practices, the authors of the research introduce various non-metallic fibres, including alkali-resistant glass fibres, carbon microfibers, three types of polypropylene microfibers, and one type of polyvinyl alcohol fibre while maintaining an equal amount of binder. The research aims to comprehensively evaluate the fibre’s influence on cement composite properties. Various types of non-metallic fibres, highlighting differences in diameters and their physical-mechanical properties with a constant amount by volume, have been considered in the research. Alkali-resistant glass and carbon fibres exhibit low values of residual post-cracking force but polyvinyl alcohol fibres demonstrate the best post-cracking behaviour, with a residual post-cracking force value. This detailed examination of fibre distribution and composition sheds light on the nuanced effects on fresh and hardened concrete properties. Notably, this work diverges from existing research by maintaining a constant binder amount and considering the quantitative distribution of fibres in a unit volume of the cement matrix, along with their aspect ratio. These findings provide valuable insights for selecting the most suitable non-metallic fibres for enhancing high-performance concrete properties.
Experimental and numerical estimation of thermal conductivity of bio-based building composite materials with an enhanced thermal capacity Piotr Łapka, Fabian Dietrich, Piotr Furmański, Maris Sinka, Genadijs Sahmenko, Diana Bajare Journal of Energy Storage, 2024 The paper tackles the important problem of estimating and predicting the thermal conductivity of bio-based building materials that can help decarbonize the building sector. Knowledge and the possibility to optimize their insulating properties is the first criterion for determining the ability of their use in the building sector. The novel yet not well-studied hemp shives and magnesium binder composites with improved thermal mass by microencapsulated phase change material (PCM) were considered. The samples of composites without PCM having different densities as well as with different amounts of microencapsulated PCM and the same density were manufactured and tested experimentally in different states, i.e., dry and after conditioning at relative humidity (RH) of 50, 75, and 90 %, and in the case of samples with PCM also at different average measurement temperatures selected with respect to the phase change range of the PCM. A novel method of predicting bio-based composites' effective thermal conductivity tensor was also developed. The method is based on the numerical solution of the heat conduction equation at the micro-scale considering real composite microstructure. The method was tuned using micro-computed tomography (μCT) data with the microstructure of composites without PCM and then applied to predict the thermal conductivities of composites with PCM, utilizing computational domains with an artificially distributed PCM in the binder. The experimental testing of composites without PCM revealed an apparent effect of increasing thermal conductivity with rising sample density and RH applied during conditioning. With an increase in density from 394 to 576 kg/m3, their thermal conductivities varied from 0.105 to 0.159 W/m/K for the dry state and from 0.157 to 0.241 W/m/K for RH 90 %. A similar effect of sample state and RH was observed for composites with microencapsulated PCM, which had the highest thermal conductivity, equal to 0.265 W/m/K, for the lowest PCM amount and RH 90 %. Moreover, a decrease in composites' effective thermal conductivity with an increase in PCM fraction was observed, except for the lowest PCM fraction, for which it increased. It also rose with increasing the average measurement temperature. The developed micro-scale-based numerical method allowed for predicting the thermal conductivities of composites with accuracies below 4.1 and 7.2 % for composites without and with PCM, respectively, except for the composite with the lowest amount of PCM, which behaved differently. Thus, its suitability for designing and optimizing bio-based composites was shown.
Behaviour Analysis of Beam-Type Timber and Timber-Concrete Composite Panels Elza Briuka, Dmitrijs Serdjuks, Pavel Akishin, Genadijs Sahmenko, Andrejs Podkoritovs, Raimonds Ozolins Applied Sciences Switzerland, 2024 This study addresses the enhancement of material efficiency and reduction in brittleness in timber-to-concrete adhesive connections for beam-type timber and timber-concrete composite panels. The research explores the potential benefits of adding longitudinal timber ribs to cross-laminated timber (CLT) beam-type panels. Three groups of flexure-tested specimens were analysed as follows: (1) timber panels (1400 mm × 400 mm) with two 100 mm thick CLT panels and two 60 mm thick CLT panels reinforced with 150 × 80 mm timber ribs; (2) eight specimens (600 mm × 100 mm × 150 mm) with CLT members (600 mm × 100 mm × 100 mm) connected to a 50 mm concrete layer using granite chips and Sikadur-31 (AB) epoxy adhesive; (3) six CLT panels (1400 mm × 400 mm × 50 mm) bonded to a 50 mm concrete layer, with two panels containing polypropylene microfibres and two panels incorporating polyethene dowels for mechanical connection. Specimens were subjected to three-point bending tests and analysed using the transformed section method, γ-method, and finite element method with ANSYS 2023R2 software. Results indicated a 53% increase in load-carrying capacity for ribbed CLT panels with no additional material consumption, a 24.8–41.1% increase for CLT panels strengthened with a concrete layer, and improved ductility and prevention of disintegration in timber-concrete composites with polypropylene microfibres.
High performance and conventional concrete properties affected by ashes obtained from different type of grasses American Concrete Institute ACI Special Publication, 2012
Use of straw-clay material in walls Civil Engineering 11 3rd International Scientific Conference Proceedings, 2011
Ultra high performance concrete hardening under pressure Civil Engineering 11 3rd International Scientific Conference Proceedings, 2011
Obtaining composition of geopolymers (alkali activated binders) from local industrial wastes Civil Engineering 11 3rd International Scientific Conference Proceedings, 2011
Effect of different mix compositions and curing regimes on ultra high performance concrete compressive strength 10th International Conference Modern Building Materials Structures and Techniques, 2010
Concrete with microfiller obtained from recycled lamp glass 10th International Conference Modern Building Materials Structures and Techniques, 2010
Application a dolomite waste as filler in expanded clay lightweight concrete 10th International Conference Modern Building Materials Structures and Techniques, 2010
Using of dolomite waste as an alternative filler in producing of concrete A Global Road Map for Ceramic Materials and Technologies Forecasting the Future of Ceramics International Ceramic Federation 2nd International Congress on Ceramics Icc 2008 Final Programme, 2008
Light weight concrete application in bridges Proceedings of the International Conference on Concrete for Transportation Infrastructure, 2005
Light weight concrete application in latvian bridges Proceedings of the Fib Symposium 2004 Concrete Structures the Challenge of Creativity, 2004
Concrete mix design and optimization Proceedings 2nd International Phd Symposium in Civil Engineering, 1998
GRANT DETAILS
Participation at the Latvian Council of Science funding project “Long-term properties of innovative cement composites in various stress-strain conditions” (No. lzp-2018/2-0249")
INDUSTRY EXPERIENCE
Development production technology in paving brick plant, foam concrete plant. Work in testing laboratory.
SOCIAL, ECONOMIC, or ACADEMIC BENEFITS
2008. Member of Latvian Concrete Society (LCA), from 2017. chairman of the board of LCA. duties: the advancement of science in the concrete industry, development of recommendation for new specification, standards and lows in the field of concrete industry.
2016. Member of American Concrete Institute (ACI) Committee 523 – Cellular Concrete.
