Enhancing Impact Resistance of Masonry Structures with Flexible Cementitious Polymer Coatings

Cement mortar is widely used in masonry construction. Mortar, although possessing good compressive strength, lacks tensile and flexural strength due to its brittle and rigid nature. Consequently, masonry structures are vulnerable to fragmentation when subjected to dynamic loads, ranging from low-velocity impacts to high-impact and high-impulse loads. These loading conditions can lead to loss of life and property damage. However, the existing masonry strengthening techniques aren’t capable of absorbing energy during dynamic loading and are not easily accessible or affordable. In this research, the feasibility of utilizing a flexible cementitious polymer coating on masonry structures subjected to dynamic loads was investigated for three coating types (0%, 5%, and 10% of overall thickness) applied on the impact face and rear face of 40 × 40 × 160 mm mortar prism specimens. Universal Testing Machine (UTM) was used to conduct three-point bending tests with cross-head speeds of 1 and 200 mm/min to simulate quasi-static and impact loading conditions, respectively, resulting in strain rates of 0.00028 s^–1 and 0.056 s^–1. The results showed that under dynamic loading, the impact face-coated specimens with a 4 mm thick coating absorbed 119.05% more cumulative energy compared to the control specimens. Moreover, the specimens coated on the rear face displayed a substantial enhancement in energy absorption, particularly when applying a 4 mm thick coating, resulting in an 889.83% increment compared to the control specimens, along with a remarkable 1346.72% enhancement in ultimate strain. The polymer coating exhibited favourable adhesion characteristics by remaining bonded to the test specimens during ultimate failure. Even with a minimum coating thickness of 5%, the coating effectively reduced fragmentation effects. The feasibility analysis revealed that employing flexible cementitious polymer coating presented a viable approach to improve the dynamic response of masonry structures. Furthermore, the optimal configuration was determined to be a 10% thick coating applied to the rear face, offering the most favourable arrangement.