Preparation and self-healing properties of cementitious composites using polymer microcapsules

Cementitious composites are prone to microcracks due to shrinkage in the early stage of curing. During service, they develop microcracks due to mechanical loads, temperature cycling and other factors. These microcracks will lead to a decrease in their durability, which is a common problem in the engineering field. To enhance the durability of cementitious composites and enable crack self-healing, this study innovatively proposes a preparation method for cementitious composites using polymer microcapsules, which are synthesized by in-situ polymerization. Under acidic conditions [pH = 2], polymer microcapsules, with a particle size of around 100 μm, uniform morphology, and excellent thermal stability, are synthesized and uniformly integrated into the cement matrix. The performance of the microcapsules and the composite materials is characterized and tested to evaluate the effectiveness of the method. The results show that under specific acidic conditions [pH = 2], the synthesized microcapsules display a uniform spherical shape, with a particle size of approximately 100 μm and strong thermal stability [main decomposition temperature above 200 °C]. Mechanical tests reveal that when the microcapsule content is 2 % [by the mass of cement], the 28-day compressive strength of cementitious specimens reaches 35.24 MPa. After damage, the recovery rate of the specimens reached 103.46 %. Crack healing experiments showed that the initial cracks of the specimens in the study group had a significant healing effect by reducing the crack width by 85% within 16 days under specific maintenance conditions. The study preliminarily confirms that the cementitious composites with microcapsules have good self-healing potential and mechanical properties, providing evidence for the engineering application of self-healing concrete.