Applying a polyurea coating to high-performance organic cementitious materials

Polyurea is a polymeric material that can be used to provide environmental protection and structural enhancement. In this study, a low modulus polyurea coating, having high elongation and energy absorption capacities and a fast gel time, was sprayed under field conditions onto the surfaces of cementitious materials. Compression tests were conducted to establish the wet–dry performance of uncoated and circumferentially coated cylinders fabricated from a high-performance matrix constructed with Poly(vinyl butyral) (PVB) as the only aggregate. Results showed that the coating increased the compressive strength of specimens exposed to both fresh and sea water environments. Similar results were obtained when a lightweight matrix containing sand was subjected to the same sea water environment. Flexure tests were conducted on uncoated and fully encapsulated plates kept under normal operating conditions to establish the stress–strain behavior of these two matrices, as well as a PVB matrix with Poly(vinyl alcohol) (PVA) fibers added as reinforcement. Results showed that the addition of the fibers and the coating increased the ultimate flexural strength, decreased the stiffness, allowed the structure to sustain higher strains prior to failure, and increased the fracture toughness. Comparisons are made between the performance of lightweight and high-performance concretes.