| Summary: | This paper had the objective of statistically analyzing the effects of the substitution of high levels of fly ash in concretes. It was produced reference concretes and concretes containing fly ash with substitutions of 30, 50, and 70% of the Portland cement mass. The water/cement material relations in these concretes ranged between 0.45, 0.50, and 0.55. With these parameters, it was conducted a factorial project 32 to analyze the results concerning the mechanical properties of compressive strength and consistency index of the concretes. It was elaborated nine concrete mixtures and their replicates. With the results obtained, it was performed a statistical analysis using ANOVA, Pareto Diagram and Tukey Test. The regression models obtained were adequate, with acceptable values of R2. The validation of the model occurred through two concretes with water/cement material ratios of 0.475 and 60 % of substitution of fly ash in relation to the Portland cement. This mixture presented an average compressive strength of 33.38 MPa at 115 days. The study showed that the ground fly ash was the most significant factor to the mechanical resistance of the concretes, significantly contributing to the increase of the compressive strength in advanced ages.
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