| Abstract [eng] |
This study aims at investigating the possibility of using dust, collected in air filters during the melting of mineral wool raw materials (mineral wool cupola dust) as an additive for Portland cement. It was found that the investigated dust mainly consists of quartz, periclase, albite, dolomite and amorphous phase. The main impurities are halite and sylvite. Investigated additive was additionally milled and prepared as microfiller. It was found, that the cupola dust additive increases the initial hydration of cement, but prolongs the dormant period. It was estimated that up to 15 wt.% of Portland cement can be replaced with dust additive without impairing the strength properties of samples after 28 days of hardening. However, after 3 months of hydration compressive strength of all samples with investigated additive are less than pure OPC samples. This phenomenon concerned with formation of significant amount of Friedel’s salt. Also, resistance on sulfate attack was tested. Results showed that RWCD additive encourages sulfate corrosion. It was decided to make composite (RWCD-clay) additive which was fired in 900°C temperature. It was found that additionally prepared dust-clay additive leads to the formation of a stable structure. Compressive strength of samples with composite additive after 3 month hydration grew gradually, as in OPC samples. When OPC is changed by 15 % with composite additive, samples with additive are as strong as OPC samples. Technological scheme of composite (70 % clay and 30 % dust) additive was suggested. |
