Effectiveness of a Natural Pozzolanic Material from Southern Saskatchewan for Cement Replacement in Concrete

Pozzolans are a category of supplementary cementitious materials that can be used as a partial replacement of portland cement in concrete. Aside from their environmental benefits, some pozzolans have been found to increase the strength, reduce the permeability, and thereby increase the durability of concrete. In this study, a natural pozzolanic material from deposits in Southern Saskatchewan was evaluated for its effectiveness as a partial replacement of portland cement in the production of concrete. Specimens with replacement amounts of 10%, 20%, and 30% by weight of cement were prepared and tested to measure compressive strength and permeability, along with a reference mix without pozzolan for comparison. The effect of sieving out particle sizes greater than 74 μm was investigated. The results showed that the 10% and 20% replacement amounts slowed down the strength development, but produced long-term compressive strengths at greater than six months that did not differ significantly from that of the reference mix, except when pozzolan particle sizes were not limited to less than 74 μm at the 20% replacement amount. The 30% replacement amount produced concrete that was weaker than the control mix by 16% and 8% at 56 days and one year, respectively, when the particle size was controlled. The permeability of samples prepared with 10% pozzolan was statistically lower than that of the reference mix and was also statistically lower when pozzolan particle sizes were limited to less than 74 μm. The natural pozzolan is therefore considered to be an effective cement replacement material