A new stain/stress sensor technology was developed, based on the concept of using Multi walled carbon nanotubes (MWCNTs) and Multiferroic nanoparticles. This new technology was manifested in concrete and mortar which greatly serve to decrease the crack depth. The use of sensors in civil structures is far from being common. In this work; there is no need to embed strain gauges or other sensors in the concrete, since the concrete itself is the sensor. The new sensor technology made use of new phenomena of the stress-induced electrical effect. This new phenomena is the change in nanomaterials/ composite contact electrical resistivity upon applying an external load on the cement composite. Concrete is somewhat electrically conducting; therefore it satisfies the basic requirement for the matrix of the composite material that senses using a new concept. The addition of conducting nanomaterials to concrete not only decreased the volume resistivity, but decreased also the contact resistivity between concrete and metal. A good electrical contact can be achieved simply by touching the concrete with the metal probe.