An Embedded Stress Measure of Concrete: A New Sensor Able to Overcome Rheology Issues

Concrete is well known to be a heterogeneous material that is usually considered homogeneous only referring to a scale of several centimetres. This characteristic makes measuring stresses inside concrete a particularly difficult task. Strains can be measured using several well-known devices. Nevertheless, it is almost impossible to derive a correct estimation of the stress within a concrete structure starting from strain measures, as the modulus of elasticity is variable and unknown and creep strains superimpose elastic ones. A long-term experimental campaign performed to test a stress sensor with the dimensions of a coin to be embedded in concrete is described in the present paper. The effects of creep, shrinkage and external applied load are measured at the scale of the bigger aggregates.