Rheological measurements on heterogeneous civil engineering materials with evolving properties

The measurement on cellular concrete, mortar, hydraulic concrete and cold bituminous mixes are presented. A non-destructive device allows the setting to be monitored and to be clearly characterized. The device is based on the propagation of compressional waves. To prevent diffraction of waves from heterogeneities, a condition of long wavelength compared to the heterogeneity size is required, so low frequencies are used (about 800 Hz). Velocity and damping coefficients versus time are deduced, then related to rheological viscoelastic properties by an inverse analysis. The rheological evolutions of the different materials are presented and compared for different mix proportions.