II. International Congress on Art and Design Research , Kayseri, Türkiye, 20 - 21 Haziran 2022, ss.1027-1035
During the production of one ton of Portland cement, approximately one
ton of carbon dioxide is emitted to the environment. It is known that the cement
industry is responsible for nearly 8% of the total CO2 emissions in the world. Today,
where sustainability is becoming more and more important, this rate is remarkably
high. One of the alternative ways to reduce this rate is to partially replace the
Portland cement with mineral additives. For this purpose, cementitious systems
have been formed by partially replacing Portland cement with 5% and 10%
metakaolin by weight; and with 15%, 20%, 30% and 35% of pumice powder. By
adding different amounts of superplasticizer to all mixtures, it was ensured that the
flow values were similar (±5%) to the flow value of the control sample without
replacement. Isothermal calorimetry tests were conducted to observe the effect of
metakaolin and pumice on the hydration kinetics. In addition, the effects of mineral
additives on the compressive strength of the cementitious mortars at 7 days and
28 days of age were investigated. In the isothermal calorimetry results, the second
peak of heat evolution curve became more evident with metakaolin replacement
when compared to cement pastes containing pumice. According to the results
obtained from the compressive strength test, it was observed that the strength of
the sample with 20% pumice was comparable to the strength of the control sample
at 7 days. At 28 days of age, the compressive strength of ternary cementitious
systems prepared with 15% pumice and 5% metakaolin replacement were
comparable to the control sample. Moreover, the addition of 15% and 20% pumice
to the system containing 5% metakaolin at 7 days and 28 days showed similar
strength values.