Rubber-cement composites for additive manufacturing. Physical, mechanical and thermo-acoustic characterization

The purpose of this work is to study the possibility of modifying a 3D printable cement-based mix by adding recycled tire rubber (TR) particles to replace the mineral aggregates. This strategy aims to evaluate the variation of some physical-mechanical properties of the material (lightness, durability, vibration absorption, acoustic and thermal insulation), promoting the disposal of the waste tires and the reduction in the consumption of natural resources. The rubberized mixture, in addition to offering interesting properties in terms of engineering performances (fundamentally important in the construction sector), can be used in additive manufacturing in the production of “bi-functional” applications. “Bi-functionality” refers to the possibility of giving a component, specific properties dependent on both the material properties and morphological structural features. Several printing mixtures, obtained for partial or total replacement of mineral aggregates with two types of rubber fillers (rubber powder and rubber granules), have been developed. After proper printability tests, an extensive experimental campaign was performed on printable rubber-cement composites: physical characterization, morphological analysis, mechanical characterization and evaluation of acoustic and thermal insulation properties. The rubber aggregates preserve optimal rheological properties related to the printability of the mixture. Besides, the synergy between the two types of polymer fillers in the cement matrix results in some interesting physical and mechanical effects: ductility, plastic energy absorption, durability, acoustic damping, and thermal inertia.