| Abstract [eng] |
Abstract: In this study, the possibility of using cement bypass dust as a cement additive was investigated. Utilization of cement bypass dust remains a major problem in cement production, as huge amounts of it are stored in landfills. In the work presented, a hydrothermal treatment is proposed to modify the properties of these dusts and to expand their use. Hydrothermal treatment with pure bypass dust and quartz was carried out to achieve a CaO/SiO2 ratio of 1 to 2. The samples were synthesized at 200 ° C 2, 4, 8 and 24 h. To examine the influence on cement properties, the sample was selected with the CaO/ SiO2 ratio 1, hydrothermally treated 8 h. This study employed the following research approaches: XRD, XRF, DSC-TG and isothermal calorimetry. Most of the target synthesis products, tobermorite and calcium silicate hydrates, form after 8 hours of sample synthesis in which quartz was added to bypass dust and a CaO/SiO2 ratio of 1 was achieved. Examination of the composition of the liquid medium following hydrothermal processing shows that almost all chlorine passes into the liquid medium, while K2O remains partially in the solid synthesis product. The synthesised additive is an effective catalysator for the hydration reactions of Portland cement. After a 28-day curing period, specimens incorporating up to 10% replacement of Portland cement by weight with modified bypass dust demonstrate compressive strengths comparable to, or surpassing, those of specimens composed exclusively of Portland cement. |
