CHARACTERIZATION OF SENSING REPAIR MATERIALS

In order to monitor construction, repairs, and maintenance of various types of structures, it is critical to develop materials used for structural applications with sensing capabilities. In this study, polymer and cement based structural grouting materials with compressive strengths in the range of 30 to 70 MPa were modified to have sensing capabilities. Piezoresistivity was considered as the sensing property and materials were tested under various service conditions in terms of strength and sensitivity. In addition, real-time application of such smart materials for low stress disaster monitoring was investigated. Also a cementitious repair material typically used in steel pipes as protective coating was investigated to evaluate the field performance in terms of shrinkage, water absorption, and strength characteristics. For the piezoresistive cementitious and polymeric materials the resistivity change was over 10 times more than the engineering strain. A specially designed polymeric composite cantilever beam detected applied pressure as small as 1.4 kPa (~0.2 psi). The compressive stress-strain relationships of the polymer and cementitious composite were modeled using a non-linear relationship and the constitutive behavior of the piezoresistive material was modeled using incremental nonlinear stress-resistivity relationship.