Flexural Behavior of Structural Foam Concrete with Hollow Polymer Spherical Fillers Under Thermal and Mechanical Loading: Numerical and Experimental Analysis

Creating low-density composite materials that can handle significant temperature changes and bending stress is a promising approach for building floating platforms. This study creates a numerical model and conducts an experimental analysis of foam concrete containing polymer spheres with different diameters and properties. Laboratory bending tests were performed on manufactured foam concrete samples containing 10 mm, 12 mm, 15 mm, 19.05 mm, and 20 mm diameter polypropylene spheres. To predict the thermophysical properties of a composite featuring structural foam concrete with embedded polymer spheres, a numerical model was developed in the Material Designer module as the first step. The resulting density, thermal conductivity, and specific heat dependences were used as input for subsequent numerical analysis in ANSYS under nonuniform temperature and bending loading, based on the nonlinear Menetrey–Willam model. By comparing load–displacement curves for different sphere sizes, the accuracy of the model in forecasting strength and deformation properties was established. The study revealed that the maximum equivalent von Mises stress was 3.3 MPa, indicating that the material operates in the elastic zone, but close to crack formation. The maximum displacement due to temperature differences was 0.087 mm, and the tensile stress in the longitudinal direction was σX = 0.18 MPa. This indicates that the composite performs satisfactorily under temperature differences from +4 °C to −60 °C. Patterns of failure of structural foam concrete specimens with polymer spheres under bending were analyzed, demonstrating that cracking starts in the lower chord of the tensile zone, weakened by the presence of the spheres.