Alga polysaccharide based bacterial encapsulation technology for potential self-healing concrete

cracks are common in concrete due to its relatively low tensile strength, often caused by external loads that generate high tensile stress. Immediate and proper treatment is essential to prevent crack propagation and costly repairs. Self-healing concrete is designed to autonomously repair cracks without external intervention, commonly using encapsulated bacteria. This study investigates the effect of Bacillus megaterium encapsulated in algae based polysaccharide shells at 2% of concrete volume. Cylindrical specimens (15 cm diameter × 30 cm height) were tested for compressive strength at 7 and 28 days. Results showed that the highest compressive strength was achieved in concrete with 2% capsules, reaching 25.85 MPa on day 7 and 32.56 MPa on day 28. Visual observation revealed visible crack closure starting around the first week of curing. SEM analysis confirmed the presence of porous, irregular capsule surfaces that facilitate bacterial release upon cracking. EDS results detected dominant elements including Oxygen (56.02%), Silicon (21.99%), and Calcium (9.38%), indicating the formation of calcium carbonate (CaCO₃) as a result of bacterial activity. These findings demonstrate the potential of biopolymer encapsulation in enhancing both strength and self-healing performance of concrete.