Fresh and Hardened Properties of 3D Printable Foam-Concrete Containing Porous Aggregates (2022-06)¶

The foam concrete or aerated concrete is most widely used for construction applications where, lightweight, thermal insulation and fire resistance are crucial. While the application of foam concrete is successful in the construction industry, the emerging technology of concrete 3D printing possesses many challenges when using foam concrete. This is primarily due to the high flowability of foam concrete, since it contains a large proportion of air bubbles, resulting in poor shape retention and buildability characteristics. This study investigates the utilization of lightweight aggregate to reduce the foam content to achieve a lightweight 3D printable mix. The expanded perlite (EP) aggregate was used as a volumetric replacement to fine sand that substantially reduced the foam content in the mix. The effect of EP on the physical and mechanical properties was studied and compared with the control 3D printable foam concrete containing sand. The results showed that the replacement of sand with EP aggregate reduces the flow properties that is suitable for 3D printing. Besides, the compressive strength of 3D printed samples was also enhanced with the addition of EP aggregates. The compressive strength of EP based 3D printed specimens at 28 days was determined as 12.95 MPa, 15.5 MPa and 10.6 MPa in the perpendicular, longitudinal, and lateral directions respectively. On the other hand, control 3D printed samples displayed the compressive strength of 5.5 MPa, 8.4 MPa and 4.2 MPa at a slightly lower density range.