Effect of the Composition of Polymer-Composite Lightweight Concrete for Floating Platforms on Their Thermal and Strength Properties

In recent years, the incorporation of voids with different geometrical configurations has emerged as one of the most effective strategies for reducing concrete consumption in structural systems. This article is devoted to the numerical analysis and experimental study of lightweight concrete using polymer spheres of various diameters and properties as voids. Lightweight concrete specimens with polypropylene spheres of 10 mm, 12 mm, 15 mm, 19.05 mm, and 20 mm diameters were manufactured. The experimental specimens were subjected to compression tests, and the results were compared with the numerical model. A numerical model employing the Menetrey–Willam constitutive model was established using spheres with comparable diameters and various types of polymers: polypropylene, polyamide 66, and polyester. The thermal properties of polymer-composite lightweight concrete (PCLC) were determined for various wall thicknesses using different polymers. The results demonstrated a 1% to 2% lower thermal conductivity coefficient for PCLC with polypropylene compared to polyethylene. Verification of the compressive strength results by comparing the data with the experiment demonstrated good accuracy in predicting the strength and deformation properties. The calculated stress and strain field distributions enabled the identification of the cracking patterns and failure mechanisms of the specimens containing polymer spheres. It has been proven that smaller radius spheres manufactured from higher modulus polymer materials have better deformation resistance and provide good, consistent strength in lightweight polymer concrete. The observed strength reduction in PCLC regarding the control composition (Rb = 21.4 MPa) without spheres is within 11% for 10 mm (Rb = 19.1 MPa) and 12 mm spheres (18.2 MPa). For larger-diameter spheres, the strength reduction reaches 25% (Rb = 16 MPa).