Pulp waste could hold the key to 3D-printing concrete buildings, with global engineers now using plant-based cellulose nanofibrils (or CNF) to build greener, more consistent and more resilient structures.
Published in the latest edition of Cement and Concrete Composites, Effects of Cellulose Nanofibrils on Rheological and Mechanical Properties of 3D Printable Cement Composites, the study uses a new type of cellulose (or a waste extracted from wood pulp) to “offer new possibilities for rapid prototyping and customisation.”
Led by Professor Osman E. Ozbulut, engineers from the University of Virginga’s School of Engineering and Applied Science found that when applied to concrete, “CNF can increase flowability for smoother 3D printing and improve its strength and durability. In addition, “testing shows that their CNF-enhanced concrete performs very well under stress, which means it could build more resilient structures.”
“The improvements we saw on printability and mechanical measures suggest that incorporating cellulose nanofibrils in commercial printable materials could lead to more resilient and eco-friendly construction practices sooner rather than later,” Professor Ozbulut said.
Why is cellulose key to material reinforcement?
As the world’s most abundant renewable organic polymer, cellulose has been extensively studied as a reinforcement material not only in concrete but also in the next generation of 3D-printed plywood and lumber.
“Cellulose-based materials, such as cellulose fibres, cellulose nanocrystals (CNC), and cellulose nanofibrils (CNF), are derived from wood pulp,” the study said. “Cellulose-based materials are suitable for use as reinforcement materials because they improve the tensile strength, flexural strength, compressive strength, and durability of structures.”
Last month, Wood Central reported that the FAO is now predicting that the demand for timber will jump 49% by 2050, driven by huge investments in cellulose, in addition to cross-laminated timbers and biomass.
“This projection focuses on the demand for wood products,” the FAO said, with “multiple pathways combining increased harvesting and processing efficiency, recycling and planting of forests and trees…(which) can lead to sustainable wood supply in volumes to meet increased demand.”
In May, Wood Central spoke to Duncan Mayes, one of the report’s contributors, who said global forest companies are now looking to use lignin, cellulose and even hemicellulose to enhance the value of wood.
“Industry is now integrating cellulose from wood into cement, used in concrete structures,” Mr Mayes said. “It enables the speed of curing of the concrete structure to be increased and even 3D printed while enhancing the strength of the concrete. It may also reduce the corrosion-prone steel needed to reinforce the concrete.”
- To learn more about how cellulose (and lignin) can be used to create the next generation of wood products, click here for Wood Central’s exclusive interview with Duncan Mayes, the founder and principal of Helsinki-based Lignutech Oy.
