Self Healing Materials

Abstract

The self-healing behaviour of materials with a particulate microstructure, which has experienced damage under uniaxial compression or tension, is studied with the Discrete Element Method. The stress-strain response of the particle system shows that the effective compressive and tensile strengths typically increase with the contact adhesion (i.e., the tensile strength between particles), where the effective compressive strength is about 5 times larger than the tensile strength. A sample with "weak" contact adhesion is selfhealed by instantaneously increasing the contact adhesion at different deformation levels from weak to "strong". The stress-strain curves of self-healed samples are bounded by an envelope curve that reflects the damage response of a sample that has a "strong" contact adhesion since the onset of loading. If self-healing is applied short before the peak stress is reached, the maximum sample strength will be close to maximum strength observed in the envelope curve. In contrast, if self-healing is initiated in the tensile softening regime, the maximum sample strength will be (significantly) less than the maximum strength related to the envelope curve.

Self-healing capacity of fiber-reinforced calcium phosphate cements

“…In millions of years, evolution developed materials with self-healing properties. These natural materials have the capability, to partially or completely restore in shape or function after the event of damage 1 . In nature there are many familiar examples of self-healing that we take for granted, such as spontaneous healing of ruptured skin or mending of broken bones.…”

“…In the recent 20 years, intense research on the development of self-healing materials was performed 1,4,5 . Hereby, several strategies are to be distinguished.…”

“…Many healing methods require external triggers, with temperature regimes being the most utilized 5 . In terms of extrinsic healing with capsule systems, the repeatability of the healing process is restricted 1 . These factors can limit the fields of potential applications.…”

Effect of age and level of damage on the autogenous healing of lime mortars

“…It is worth here remarking that a lot of studies in the last decade has been dedicated to the self-healing capacity of cement based materials [11,12] and several authors have investigated tailored additives or techniques purposely designed to enhance this capacity [13]. As a matter of fact the self-healing capacity depends on several factors, such as the mix composition of the matrix, the age of damage, the damage level, the external conditions (temperature, moisture) and the curing time [14].…”

Overview of recent work on self-healing in cementitious materials

“…Evidence of self-healing to material design was apparent at the first international conference on self-healing materials which was held in the Netherlands during April 2007. This conference has also been succeeded by the first two books devoted solely to self-healing materials (20,21). In 2005 a RILEM technical committee was established charged with investigating self-healing phenomena in cement-based materials, as stated by Joseph (22).…”