Knowledge of particle concentration is of extreme importance for the settling phenomenon. For well-diluted suspensions the solids concentration can be measured by sampling techniques. However, the use of such a technique for more concentrated suspension does not lead to good results. Knowledge of concentration distribution in sediments formed by decantation of aqueous suspensions inside a vertical vessel is fundamental for the evaluation of performance of some pieces of equipment such as continuous thickeners. In this work, the phenomenon of batch settling of aqueous suspensions of calcium carbonate was studied by using a nondestructive technique based upon the measurement of gamma-ray attenuation when the radiation beam goes through the physical medium as a function of the local concentration in several vertical positions of the vessel, and the sampling of suspension by aliquots is not necessary. The main objective of this work is to evaluate the use of gammaray attenuation technique for achieving concentration distributions in the phenomenon of batch settling as well as curves of iso-concentrations.