Modeling and Optimizing the Effect of 3D Printed Origami Bubble Aggregate on the Mechanical and Deformation Properties of Rubberized ECC

A recent development in the production of lightweight concrete is the use of bubble or hollow aggregates. Due to its exceptional energy absorption and ductility properties, engineered cementitious composite (ECC) is increasingly recommended and used for structural applications, particularly in earthquake-prone regions. As a result, researchers have started looking into the benefits of lightweight ECC for such applications. However, the strength is considerably compromised due to the use of lightweight fillers such as perlite, cenospheres, glass microbubbles, and crumb rubber (CR). This study evaluates an origami-shaped bubble aggregate (OBA) novel application in rubberized ECC (RECC) to achieve density reduction at a relatively lower strength loss. The experiment is designed using response surface methodology (RSM) with the spacing of the OBA at 10, 15, and 20 mm and its quantity at 9, 15, and 21 as the input factors (independent variables). The dependent variables (responses) assessed are density, compressive strength, modulus of elasticity, and Poisson’s ratio. The results showed that adding the OBA lowered the density of the RECC by 20%. It was revealed that using up to 15 OBAs with spacings between 15 and 20 mm, a lightweight OBA-RECC with substantial strength could be produced. Similarly, utilizing 15 and 21 OBAs at 20 mm spacing, a lightweight OBA-RECC with a comparable modulus of elasticity as the control could be developed. Models for predicting the responses were developed and validated using analysis of variance (ANOVA) with high R2 values. The spacing and quantity of the OBA’s optimal input levels were determined using the RSM multi-objective optimization to be 20 and 9, respectively. These levels produced optimal responses of 1899 kg/m3, 45.3 MPa, 16.1 GPa, and 0.22 for the density, compressive strength, modulus of elasticity, and Poisson ratio, respectively.