In this work two fiber optic sensing techniques are used to study the dimensional stability in fresh state of different
cementitious materials. A conventional Portland cement mortar and two commercial grouts were selected. The
measurements were performed by using a Bragg grating embedded in the material and a non-contact Fizeau
interferometer. The first technique was applied in a horizontal sample scheme, and the second one, by using a vertical
configuration. In addition, a mechanical length comparator was used in the first case in order to compare the results. The
evolution with time of the dimensional changes of the samples and the analysis of the observed behavior are included.