Rohollah Rostami

PhD Student
Project title: Development of Green Repair Materials for Seismic Regions

The current construction industry is faced with ever rising demands for safer and more cost-effective infrastructure. The way to address these requirements is to look towards multidisciplinary approaches in the developments of new sustainable building materials but also in the developments of new repair technologies. Such an approach would require experts in diverse fields such as materials engineering, chemistry and building physics.

One of the most common problems in the use of cementitious materials is shrinkage due to the hydration reaction. This process often leads to cracks in the cement matrix in the early days after casting. This phenomenon is more marked in cementitious materials which contain fine aggregate or that are subject to a rapid evaporation of the water contained in the mix. Typical examples are mortars, which used in thin layers, must contain very small aggregates. They are also subject to a rapid evaporation of water due to large surfaces exposed to the atmosphere. The problem is even more severe in the seismic regions when repetitive load applications widen the cracks. Two valid technologies used to cope with this phenomenon are to introduce fibres or superabsorbent polymers (SAP) in the mixture. Both techniques have the same purpose but the principles of actions are different. The fibres give to the material an additional tensile strength to withstand the stresses induced by shrinkage. On the other hand the polymers absorb water during the mixing and release it during hydration favouring internal curing. They alter the reaction time and provide water allowing an increase of volume of hydration products.
The main aim this study is to evaluate combined effect of polymeric fibres and Superabsorbent polymers on the performance of repair mortars and in consequence and develop a new generation of cementitious composites with self-healing properties.