New self-healing techniques for cement-based materials

In recent years, researches concerning cement-based materials has been focused not only on the strength and the toughness but also on the durability. In fact, the interest on concrete's self-healing process is increasing, due to the rapidly deterioration of that material which tends to crack and thus quickly deteriorate. In this paper, a new self-healing technology for cement-based materials is proposed. This technology is based on the encapsulation method of repairing agent inserted in randomly distributed shell inside the material during its preparation. Two different kind of shells were used: glass spheres and pharmaceutical capsules. The material the shells are made of has to be endowed with a series of fundamental characteristics. That material has to be inert with respect to the repair agent so that it doesn't react with it, resisting to the severe stress condition that the shells undergo during the mixing, and at the same time being capable of breaking down when the crack intercept them, having a good compatibility with the cement mixture. The results demonstrate that it is possible to use this kind of shell to encapsulate the repairing agent: the crack breaks them and they release the healing agent, which allows patching up the crack.