Low clinker ECC materials using biomass ash for 3D printing

Concrete buildings in service are frequently subjected to dry shrinkage, temperature stress, humidity variations, static and dynamic loads, and other undesirable external variables, resulting in varying degrees of damage exhibited as cracks or micro-cracks. These issues can be mitigated or overcome in part due to the construction industry is constantly evolving, as seen by the development of cement-based matrices with self-healing properties: Engineered Cementitious Composites, ECCs, are a good example of that. These materials including PVA (polyvinyl alcohol) fibers and a high proportion of fly ash (FA) in their composition, belong to a family of high-performance fiber-reinforced composites that have more ductility than standard concretes. Also, they have the ability to self-healing using autogenous mechanisms. Due to the scarcity of FA (thermal power facilities are closing down in some regions of the world) that are employed in ECC, the substitution of fly ash by biomass ash (BA) has been studied with good results in previous research. The construction sector is evolv-ing not only from the design of material point of view, this industry is in con-stant progress also from the perspective of the development of new technolo-gies. An example is the appearance of 3D printing which has some advantages in comparison to traditional technologies as more modeling freedom, less mate-rial consumption, and environmental pollution, making it eligible for green and smart construction.
In the current work, the next step is evaluated: reduction of the cement per-centage in the formulations and the adaptation of these new formulations to 3D printing requirements. ECC formulations were created for these purposes, where cement content is reduced by increasing the BA percentage. Fresh and hardened properties and self-healing capacity of the novel cement-based mate-rials for 3D printing were assessed.
Results show good behavior of these new ECC matrices based on BA, which allows their use in 3D printing technologies and agrees with the new environ-mental policies and Circular Economy