Optimization of multifunctional nano cement composite for self – sensing

Abstract

Abstract The invent of new construction materials and extensive research in concrete technology and cement chemistry has proved that apart from proportioning concrete for high strength it is very important to design a concrete mix for high performance in terms of diagnosing damage like smart materials. The use of mineral and chemical admixtures in concrete has facilitated the material scientists to invent special types of concrete to suit the current application. Materials that are used in concrete like steel fibres, carbon nano fires (CNF) and carbon nano tubes (CNT) with appropriate dosage, can impart this self-sensing property in concrete. These multifunctional smart materials have resulted in assessing the damage to structures without the need for any external sources like sensors or any structural health monitoring device like optical fibres. The inclusions of nano materials in cementitious matrix that are conductive in nature provide a new type of self-sensing composite. Self-sensing material have the ability to sense their own conditions like stress, strain, temperature and damage. This property of the material which enables itself to assess its own damage and deformation has made it a smart material for health monitoring. Appropriate use of this smart material with a well-defined sensing scheme can enhance the sensitivity of damage detection in micro level which can prevent the collapse of the structure. CNT and CNF were used in 0.1 to 0.3% by weight of cement and their electrical conductivity was measured which gives a good relation of the self-sensing properties of the material. Cyclic compressive load was conducted and the response to the piezoresistive properties of the nano composite was tested. It was observed that 0.1% of these carbon nano materials had better electrical properties.