Effect of the Interfacial Transition Zone on ultrasonic wave attenuation and velocity in concrete

Elastic stiffness estimation of aggregate–ITZ system of concrete through matrix porosity and volumetric considerations: explanation and exemplification

“…Note that the water content of the cementitious matrices discussed above can be changed, but the nature and the proportion of the other components must remain constant, since their modification would imply different E 0 and k coefficients [35]. Additionally, note that the elastic stiffness of the aggregate-ITZ system, measured by E a-ITZ , will be considered regardless of the water content of the concrete mixture and any eventual change in ITZ bonding behavior due to that variable [15]. This statement is not all together evident and will be further discussed in the following sections.…”

“…Greater adherence between these two components will imply less slippage in these zones and, therefore, greater stiffness when loads are applied [14]. Adherence depends on the surface properties of the aggregate and the nature of the cementitious matrix [15].…”

“…The elasticity of the aggregate-ITZ system can be defined as the modulus of elasticity of the aggregate suitably corrected by the slippage between the aggregate and the surrounding cementitious matrix when loading is applied [14]. The elastic stiffness of the aggregate-ITZ system therefore depends both on the type of aggregate and on its interaction with the surrounding cementitious matrix; adherence will not only differ when changing the aggregate type, but it will also differ when modifying the composition of the cementitious matrix [15].…”

Numerical Study of Concrete Mesostructure Effect on Lamb Wave Propagation

“…The particle shape depends on the aggregate type. However, after other researchers [ 17 , 19 , 22 ] and for the sake of simplicity, in a later part of the paper, we assume that they are spherical.…”

“…Although the papers published by Xu et al [ 17 ], Abo-Quadis [ 18 ], and Ramaniraka et al [ 19 ] deal with the impact of the concrete mesostructure on waves characteristics, the problem of wave propagation in heterogeneous materials is still not considered in detail, yet. The existence of aggregates varying in size, shape, and material parameters, and pores and cracks may lead to additional disturbing phenomena like scattering, diffractions, and wave attenuation affecting wave amplitude or propagation velocity, which were commonly used as indicative parameters in the above-mentioned studies.…”