Isophorone Diisocyanate (IPDI) Microencapsulation for Self-Healing of Cementitious Materials
Subject Areas : Advanced Materials in Structural Engineering
Komeil Farshidi
1
(
Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
)
Abbas Akbarpour
2
(
Assistant Professor, Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
)
Asghar Habibnejad Korayem
3
(
School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
)
Morteza Ebrahimi
4
(
Department of Polymer Engineering & Color Technology, Amirkabir University of Technology
)
Keywords: Self-healing, Microcapsules, Microencapsulation, Isophorone diisocyanate (IPDI), Cementitious Materials,
Abstract :
Since cementitious materials are brittle, they are prone to cracking. Cracks could be healed via autogenous methods namely healing microcapsules.The objective of this study was twofold. First, microencapsulation of isophorone diisocyanate (IPDI) as a catalyst-free healing agent. Second, evaluation of microcapsules effect on promotion of cementitious materials healing capability. PU prepolymer was synthesized and smoth spherical microcapsules of IPDI with average diameter of 48-62 μm were produced successfully. The microcapsules shell wall thickness varied linearly with microcapsule diameter and so, the shell wall thickness to diameter ratio was constant (~0.04).The microcapsules weight loss in a 6 months period was ~12.47% under ambient conditions. The mortars containg 3% of their cement weight IPDI microcapsules, had up to 74% recovery rate of compressive strength while this rate for control mortars (with no microcapsule) were less than 50%.EDS analysis of healed mortars, showed noticable amount of carbon in the areas of ruptured microcapsules and healed cracks, confirming that healing process had been precisely accomplished according to the theory of self healing assumed.Samples containig micocapsules had higher initial compressive strength in comparison with control ones, indicating that there had been an undesired rupture of portion of microcapsules during prepartion and molding of specimens. This demonstrated need of more studies and work on mechanical properties of microcapsules specially stiffness of those used in cementitious composites.