Despite the importance of the Weibull modulus in reliability analysis of brittle materials, the majority of the studies are focused on plain concrete; the data being especially scarce for nano-SiO2-concrete. Therefore, this paper investigates the concrete tensile strength up to quaternary designs containing fly ash, micro- and/or nano-SiO2. Splitting failures were carried out at 3, 7, 28, 56 and 90-days. Quadratic class goodness-of-fit tests of composite hypothesis were applied to investigate the accuracy of the two- (We2) and three-parameter (We3) Weibull models. The estimated Weibull parameters were obtained using maximum likelihood (MLE) and other nonlinear methodologies. This practice enables to overcome divergences in some datasets associated with the solely use of MLE-We3. Results showed that the We3 represented the model with the best fit (71%) in comparison to the We2 (25%). However, differences through time in the mean Weibull moduli were not significant based on ANOVA analyses. Articulo tipo A1