Studies on blended cements containing a high volume of natural pozzolans


The characteristics of laboratory-produced blended portland  cements containing 55 wt% volcanic tuffs from Turkey were studied. Volcanic tuffs from two different sources were used. Using different grinding times, particle size distribution, setting time, compressive strength, and alkali-silica activity of the blended cements were investigated and compared with reference portland cements ground for the same period. For the compressive strength test, a superplasticiser was used to obtain mortar mixtures of adequate workability at a constant water-to-cement (w/c) ratio of 0.45. Compared to portland cement, the blended cements containing 55% pozzolan showed somewhat lower strengths up to 91 days when the grinding time was 90 min. However, at 91 days, blended cements and portland cements ground for 120 min showed similar strength. Moreover, blended cements containing 55% natural pozzolans showed excellent ability to reduce the alkali-silica expansion.  7 refs.

Primary author(s): Uzal B; Turanli L

                            Ankara,Middle East Technical University

Source: Cem.Concr.Res.


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