LabLab is the mascot of RTU Science and Innovation Centre, and this new sculpture is much more than a mascot: it is a large-scale prototype for the Transforming Waste Into High-Performance 3D Printable Cementitious Composite project, using our developed 3D printable mix and now being tested in real outdoor conditions. A nice moment where research, industry collaboration and a bit of playfulness meet in one printed object.

A huge thank you to everyone who helped LabLab 2 come to life:
👉 Project partners: SAKRET Baltic, Kaunas University of Technology and ZAG – Zavod za gradbeništvo Slovenije
👉 RTU 3D lab team for developing and optimising the mixes and working on the prototype
👉Printstone Innovations SIA for assembly
👉Creative Tuesdays, Morberga Studija, DigiSplit LTD for organising and supporting the student competition
👉 Student competition mentors: Roberto Naboni, Dr. Slava Markin and Arturs Veiss
👉 Dr. Elina Mikelsone for the original idea to print LabLabs and for keeping the LabLab birthday tradition alive

Looking forward to seeing what we learn from this prototype and how it will feed back into the next generation of sustainable 3D printed structures.

IExciting times are ahead at our lab! The installation of the large-scale prototype LabLAB 2.0 has officially begun, marking a major milestone for our research and development efforts. This landmark prototype has been designed in collaboration with students—through their competition contributions—and built using the very mixtures developed within our project framework, with a substantial amount of oil-shale ash incorporated as a key material. The result is a tangible embodiment of our vision for sustainable and high-performance building materials.

The grand unveiling is scheduled to coincide with the birthday celebration of the “LabLAB” itself, which takes place in mid-December (date to be confirmed). During this event, invited guests, industry partners, and research collaborators will witness the completed prototype in all its form and function, accompanied by insights into the design process, material development, and on-site installation journey. Stay tuned for more updates as we draw closer to this milestone — we’ll be sharing sneak-peeks, behind-the-scenes shots, and the story behind how this unique large-scale prototype came to life on Instagram page of our lab.

To mark this milestone, we are excited to unveil our own major achievement—a groundbreaking 30 MPa 3D-printed concrete made entirely from cement-free binders and recycled construction waste. Remarkably, 92% of its composition consists of recycled materials, setting a new benchmark for sustainable building solutions. ♻️🏗️

Here’s to the next decades of innovation, sustainability, and progress in concrete technology! 🚀

The IMST 2025 Conference will bring together researchers, industry professionals, and experts to discuss the latest advancements in materials science, structural engineering, and construction technologies.

Building on the success of previous editions, IMST continues to provide a platform for high-quality scientific exchange, fostering collaboration and innovation in the field.

Key Highlights

• Scientific sessions featuring cutting-edge research
• Workshops and discussions on emerging topics
• Networking opportunities with industry leaders and researchers

Special Focus: 3D Printing in Construction

This year’s conference will include a dedicated session and workshop on 3D printing in construction, showcasing advancements in:
✅ Cement reduction strategies using waste materials
✅ Cement-free 3D-printable mixtures with recycled aggregates
✅ Bio-based material printing
✅ Printing with recycled polymers

🔗 More information and updates: www.imst.rtu.lv

Join us in Riga for IMST 2025 and be part of the future of innovative construction!

https://rtucloud1.zoom.us/j/91041220374?pwd=AnEajaVbibL5H3FkR6TreNoQp0mweq.1

An opportunity to participate in the 2nd 3D Concrete Design Competition, organized by TRANSITION project. The competition will take place online, and by the end of the year, participants will need to develop a technical design for the second large-scale 3D concrete sculpture, which is planned to be installed at the Riga Technical University (RTU) student campus.

The competition will be held in English, and both students and professionals interested in innovations and 3D printing technologies are invited to apply. Registration for the competition is open until October 22nd at the following link: https://ej.uz/3DCD.

Additionally, expert support and consultations will be provided throughout the competition. Participants will have the opportunity to gain knowledge about various 3D printing techniques, material properties, and design optimization. Participation is free, and the prize fund is set at 2000 EUR.

Follow competition updates on the Facebook page — 3D Concrete Competition: https://www.facebook.com/concretecompetition.

The first online workshop, titled “Making of the Most Loved 3D Concrete Sculpture,” will take place on October 22nd at 18:00. In this session, attendees will learn about this year’s competition task and the creation of RTU’s mascot and beloved astronaut — LabLab 1.0. Facebook event link: https://www.facebook.com/events/1220157565800140.

The competition is organized in collaboration with the “3D Concrete Competition,” the research and innovation platform “Morberga Studija,” the creative education platform “Creatives Tuesdays,” the construction mixture manufacturer “SAKRET,” the young architects’ club “Atelpa,” the RTU Science and Innovation Center, and the startup “Printstone Innovations.”

Here are some photos from the final event of the previous 3D Concrete competition held in 2022, including the three winning designs.

At the beginning of September, our project researchers had the opportunity to participate in a digital construction seminar in Braunschweig, organized as part of the AMC – TRR 277 project. There was a unique opportunity to see the large-scale framed 3D printing machine COBOD-BOD2 in action, which is particularly suited for printing large-scale objects (with dimensions of up to 8x15m). We were also personally introduced to both BAUBOT robots, which operate on this digital construction site.

After the seminar, we attended the world-leading conference on digital concrete technology, Digital Concrete 2024, in Munich. It was truly inspiring to listen to presentations from leading experts on their experiences with digital construction and to hear their perspectives on future research in construction optimization and the reuse of various materials.

Alice Sapata gave a presentation on 3D printable cement-based composites with oil shale ash, which is a part of this project.

Find the proceedings here https://digital-concrete.com/frontend/index.php?folder_id=9304&page_id=

Additionally, had the chance to visit newly opened pavilion by 3DPGroup and icon BOD – Europe’s first 3D printed building finished in 2017 by COBOD – both located in Copenhagen.

In May 2024, as part of the M-ERA.NET project “TRANSITION,” project team from RTU and SAKRET had the opportunity to visit our project partners at the Slovenian National Building and Civil Engineering Institute (ZAG) in Ljubljana, Slovenia. The goal of this visit was to share knowledge on the tests conducted so far and to align our research goals and future ideas. For some of the team, the visit was planned for a few days longer to carry out 3D printing and fresh concrete tests that could only be done at ZAG.

PART I   PRESENTATIONS, DISCUSSIONS AND FUTURE PLANS

On the first day Project leader M. Sinka briefly summarized all the dissemination activities carried out within the framework of this project so far. Regarding dissemination, he also introduced everyone to the student competition planned for the following months. We had a brief discussion about this, and we concluded that this competition could easily be made international so that students and representatives from all the institutions participating in TRANSITION project could apply.

Within the framework of this project, it is planned to create a large-scale object – LabLab astronaut – for which we already printed a smaller-scale prototype this winter. Even though the architectural design for this object is somewhat finished, there is still a need to develop the technical design. The technical design would include solutions for assembly, detailed drawings, 3D models, and other elements. This is where the student competition comes in. The idea is that each student group would be assigned a mentor to help realize their ideas for technical solutions and their execution. At the end of the competition, the best group will be rewarded with a prize.

3D model of the LabLab astronaut

Later on this day we continued on with the meeting. Each project partner presented their latest work and progress. This was very important to discuss and understand in which directions to conduct further research. For example, when RTU presented their newly acquired disintegrator, it initiated a discussion on the potential for milling ashes in a wet state, which could be an interesting direction to explore.

G. Sahmenko from RTU introduced the rest of the project participants to the mechanical properties of preliminary mixtures. Based on these mechanical properties, optimal mixture proportions for a trial mixture for 3D printing has been developed. So far this trial mixture has been printed out once and from that it was concluded that particle packing needs to be improved. Based on everyone’s experience, it was discussed which materials, either microsilica, finely milled limestone or others, would be the best additives in this case.  A. Sapata shared her experiences with various fresh mass property tests, such as unconfined uniaxial compression test, squeeze flow test, mini cone test, and slugs test. Some of these tests will be incorporated into our plan for determining fresh mass properties later in the week. B. Migliniece from SAKRET reported about works completed from their side, ZAG reported on their work.

At the end of this day we had a guided tour through Ljubljana. This was not a tour for the regular tourist, but more like a detailed explanation of how the architect Jože Plečnik (1872 – 1957) and his descender Edvard Ravnikar (1907-1993) participated in the creation of the landscape of this city as it is now. The guide introduced us to some apparently very well-known architectural landscaping ”tricks” that these architects used in their work, such as playing with perspective and geometric forms to create illusions, outline specific buildings, and create the overall view.

The Ljubljana Central Market by Joze Plecnik.

On the second day of our visit, we started out with a laboratory tour. We were introduced to both new tests and some new colleagues. Particularly interesting was the small concrete press used to compress cubes 2x2x2 cm. The laboratory workers also shared some tips and tricks for everyday work in a concrete laboratory. They suggested that it is better to use silicone molds for geopolymers but leave the metal ones for cement. They showed us how they store their equipment, how accurately they mould samples so that highly precise results can be obtained even from very small samples, and showed us how to correctly perform tests, for example, the LeChatelier test.

From the left: silicone moulds for small mortar prisms; flexural strength device; a self-made compressive strength device for samples 2x2x2cm.

All of the ZAG’s guests were introduced to the 3D printing laboratory and some of the objects that had been printed out so far. Particularly interesting was the rope-like texture of the printed concrete objects that is created by the 3D printer.

Texture of the printed objects.

After lunch, we had a discussion on the development of a small-scale prototype for 3D printable concrete mixes. L. Hanzic led the presentation on the key geometric features and parameters necessary for the prototype, considering the limitations of different printer types. Afterwards, K. Ster presented how ZAG has organized our project data on the open-access server, OSF, ensuring transparency and accessibility. The main takeaway from this was the importance of data storage so that information can be easily accessed even five years from now. We know this is a struggle for many.

Thus far, we have obtained and processed data for only one type of raw ash. However, there are three additional types of ashes that we haven’t worked with so far: Auvere electrostatic filter ash, Auvere bottom ash and Enefit 280 ash, both disintegrated and raw. During this discussion, we decided which raw material tests need to be conducted so that we can compare all the ashes and make conclusions on their suitability for use in concrete composites for 3D printing.

Different types of ashes

On the third day, we had multiple individual meetings to discuss specific problems and questions that have not been addressed so far or are too complex to be addressed in online meetings.

All of the presentations and discussions were not only informative but also inspiring, providing us with new ideas and approaches for our project. This project is not just about researching and analyzing the properties of raw materials and developing mixtures; it is also about storing data, sharing knowledge through scientific articles, and promoting 3D printing through competitions, thereby involving new people in the field. Alongside all these processes, we came up with new ideas that we will try to include and explore, and even if they are unsuccessful, we will definitely learn a lot from them.

PART II 3D PRINTING AND TESTING

The plan for the final days was to carry out 3d printing and fresh state tests on ready-made mixture for 3D printing. Before starting, we discussed in detail the plan for the following days. Various fresh state tests were planned, such as the Slugs test, unconfined uniaxial compression test, Vane test, rheometer, ultrasound test and hardened state compressive strength tests as well. The main goal of each test was to determine yield stress at different time intervals: 5min, 15min, 30min and 50min.

Preparation process for 3D printing.

First, the Slugs test was performed. This is a relatively new test method that helps determine the approximate yield stress of extruded materials. The test is based on measuring the mass of slugs extruded through a 3D printer. Depending on the length and the weight of each slug, it is possible to determine the material’s yield stress using the formula. This test was already performed at RTU using their portal-type printer and the same ready-made mixture for 3D printing many times before. It was interesting to find out that the same mixture showed the same yield stress when carrying this test out on the completely different 3D printed in ZAG.

The Slugs test.

The unconfined uniaxial compression test allows to determine the compressive strength, yield stress, and the modulus of elasticity of fresh concrete at different ages. Additionally, using the results of this test, it is possible to determine the rate at which these parameters change over time.

For this test, the chosen sample size was H=100mm and D=50mm, maintaining the ratio of H/D=2. This size was selected as optimal after performing multiple test trials where it was concluded that it best represents the printed object dimensions. If smaller samples are used, they are significantly affected by pores and voids formed during molding, while larger samples are more influenced by gravitational forces – due to higher vertical stresses, they tend to spread more laterally. Molds composed of two half-cylinders were used to minimize lateral deformations during demolding.

Since compression samples have a very small compression area and the material has very low compressive strength in its initial stage, a highly sensitive apparatus is required. This apparatus must be capable of precisely reading deformations and the applied load value. For this reason ZAG and KROKK had developed a small, portable compression apparatus with a load cell capacity of 500 N. The frame consists of four posts to which a sliding load plate and fixed electronics plate are attached. Specimens were cast directly onto a reaction platform. The platform is not moved so that the specimen is not disturbed before the test.

On the left: compression apparatus developed by ZAG and KROKK. On the right: samples before and after the compressive strength test.

Vane test comes from soil mechanics and is used to obtain shear strength of a cohesive soil. The used Hand Vane Tester comprises of four blades making 90º to each other and a torque head with a direct reading scale which is turned by hand. The Vane device was inserted inside each sample to a constant depth. While holding the sample firmly, rotation of the vane was initiated mechanically and rotated until a maximum torque value is obtained. At this point the yield stress is recorded.

The used hand Vane tester and test cylinders where the Vane device was inserted at specific time intervals.

It’s one thing to learn from presentations, seminars, or scientific articles, but quite another to conduct actual tests, especially those recently introduced. Conducting these tests with together with colleagues from ZAG using their equipment provided valuable learning experience. We’ve gained some new knowledge and intend to incorporate some of these tests into our fresh test routine in the future.