Low-temperature differential scanning calorimetry (LT-DSC) is used to investigate the microstructure of tricalcium silicate pastes, hydrating in pure water and in the presence of comb-shaped polycarboxylate ether superplasticizers. LT-DSC is shown to be a powerful technique, able to provide important information on the porosity and on the fractality of the porous evolving matrices by means of rapid and nondestructive measurements. In particular, LT-DSC gives a semiquantitative estimation of the evolving porosity (capillary, small gel, and large gel pores), the depercolation threshold of the capillary pores, and the fractal dimension associated with the probed porosity. The results are in good agreement with those obtained by small-angle scattering methods ensuring that this approach, based on the well-established and easily accessible DSC technique, can provide valuable information on the evolving porosity and the fractal nature of hydrating cement pastes.