Preliminary Mechanical Analysis of Rubber-Cement Composites Suitable for Additive Process Construction

Abstract

Additive manufacturing for cementitious materials represents the most attractive frontier in the modern context of Construction 4.0. In addition to the technological progress of printing systems, the development of functional and low environmental impact printable mixtures is one of the current challenges of digital fabrication in building and architectural fields. This paper proposes a preliminary physical-mechanical analysis on environmentally friendly mortars, compatible with the extrusion-based printing process, made up of recycling rubber aggregates deriving from end-of-life tires. In this study, two groups of rubber particle samples (0–1 mm rubber powder and 2–4 mm rubber granules) were used to partially/totally replace the mineral fraction of the reference printable mixture. Four tire rubber powder-granules proportions were investigated and control mortar (100% sand) was also prepared to compare its properties with those of the rubber-cement samples in terms of printability properties, mechanical strength, ductility, and structural isotropy. Based on the experimental results, the rubber aggregates increase the mixture fluidity, promoting better inter-layer adhesion than the neat mix. This leads to greater mechanical isotropy. As already investigated in other research works on Rubber-Concrete technology, the addition of rubber particles increases the ductility of the material but reduces its mechanical strength. However, by correctly balancing the fine and coarse rubber fraction, promising physical-mechanical performances were demonstrated.

Recent Advances in Geopolymer Technology. A Potential Eco-Friendly Solution in the Construction Materials Industry: A Review

“…In the EP method, the cementitious mix rheology (slump, flow, and setting time), the deposition parameters (pressure and speed of printer head), and the architecture of the printing system (nozzle section and shape) affect the print quality in terms of filaments dimensions, inter-layer adhesion, extrusion regularity, and structural solidity of the printed object. The method does not allow high-print resolutions (4-6 mm maximum resolution) but is suitable for both small-scale and large-scale manufacturing processes allowing, in the latter case, easy implementation of structural reinforcements [84,85].…”

Composite Material Recycling Technology – State-of-the-Art and Sustainable Development for the 2020s.

“…Waste tires (GTR and RTR, Regenerated Tire Rubber) can be used as a source of valuable raw materials in different polymeric matrices for the manufacture of low-cost products and a cleaner environment [46]. Rubber-Concrete technology: addition of rubber particles increases the durability of the material but reduces its mechanical strength -by correctly balancing the fine and coarse rubber fractions promising physical-mechanical performance can be obtained [48].…”

Influence of Waste Tire Rubber Particles Size on the Microstructural, Mechanical, and Acoustic Insulation Properties of 3D-Printable Cement Mortars

“…Currently, the extrusion-based printing process is the most explored additive manufacturing option in academia and industry [1,5]. Similarly to fused deposition modeling (FDM), a visco-plastic cementitious material is extruded out of a deposition nozzle that prints the cement layers.…”

“…Extrudability (the ability of the material to be deposited regularly and without interruptions in the extrusion system), buildability (the ability of the printed layers to hold the subsequent layers on top of them without collapsing phenomena), and inter-layer adhesion (internal compaction of the material due to the correct cohesion between the printed layers) are considered key indicators about the print quality. In this regard, the fluidity and stiffness of the compounds should be properly balanced to meet the requirements described above [1,[5][6].…”

“…The objective is to combine the technological functionalities conferred by rubber with the performance of additive manufacturing in terms of design flexibility, structural optimization, and low pollution. Several efforts were already conducted by the authors on this topic, involving preliminary printability and print quality studies to explore the potential of incorporating recycled tire rubber particles into printable cementitious mixes [5,7,13], experimental characterization on durability analysis [13], the effect of rubber-based modification on thermal insulation properties [7,15], first mechanical investigations and modelling [5,7,15,16]. From the perspective of rational production of secondary raw materials by the tire recycling companies, economic impact and material performance, the novel purpose of the present study is to deepen in detail the influence of rubber particle size on the fresh and hardened properties of printable mortars.…”