Additive manufacturing with cement-based materials, commonly referred to as 3D printing with concrete, is gaining momentum in civil engineering as a result of technological improvements leading to the commercialisation of printing equipment. However, materials used for 3D printing normally contain large quantities of cement and other high-value powders, either inert or reactive, to ensure cohesiveness and, thus, printability. Consequently, 3D-printed structures have a high carbon footprint. In principle, when considering cast concrete, high cement content yields high compressive strength and generally improves durability. This is not the case in printed structures where strength is governed by interlayer bonds and microcracking due to shrinkage effects. Thus, high dosages of cement are not justified, and more sustainable cementitious composites need to be developed to make the technology acceptable on a larger scale.
One of the materials that have the potential to reduce the carbon footprint of printed structures is oil shale ash. In the Baltic states, oil shale is an important natural resource utilised in power plants. Consequently, large amounts of oil shale ash are already available and according to the preliminary research, this material is a viable substitute for cement and high-value powders in printable concrete. However, cement-based mixes for 3D printing are fine-tuned compositions of active and inert particles, water and chemical admixtures and as such, they are sensitive to small changes in composition. Development of printable mixes thus requires advanced characterisation methods not available in concrete plants. Therefore, one approach to making 3D printing of cementitious composites a practicable construction technology is formulating specially designed blends of all ingredients (except water).
Based on these deliberations, the following project objective is defined:
Objective
Develop a high-performance cementitious composite which utilises a large proportion of industrial waste, in particular oil shale ash, and is suitable for extrusion-based additive manufacturing (3D printing) of full-scale structural elements and buildings.
Project funding:
ERA-NET and other coordination measures
Project results:
A scientific article in periodical scientific publications published abroad with a citation index (Impact Factor) in the Clarivate Analytics (formerly Thomson Reuters) Web of Science database – 2 units.
An article in peer-reviewed international conference proceedings that has all the components of a scientific article – 1 unit.
Period of project implementation: 2023-09-01 - 2026-08-31
Project coordinator: Riga Technical University
Project partners: Kaunas University of Technology, SIA SAKRET, Slovenian National Building and Civil Engineering Institute
