Prüfung der Eignung von Gießpfannenschlacken für den Einsatz als Substitut für Hüttensand in Zementen

Translated title of the contribution: Investigation of the suitability of ladle slags for use as a substitute for blast furnace slag in cements

Milutin Bjelic

Research output: ThesisMaster's Thesis

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Abstract

Goal of this thesis is to evaluate the suitability of ladle furnace slags originating from the production of various steel products as additive in concrete products regarding their strength and soundness behaviour. As reference for this determination values from the standards EN 197-1 and ÖNORM B 3309-1 were used. Granulated blast furnace slag was furthermore beneficiated in the same manner and used as reference alongside the required values from the standards. To characterize the samples chemical analyses were conducted and a phase analysis using X-ray diffractometry (XRD). Further an eluate analysis was conducted to determine the amount of water-soluble Chromium [VI] of the slags. The material densities were determined using a helium pycnometer. The slag samples were moreover examined regarding their comminution behaviour. For this evaluation the ladle furnace slags were crushed using a laboratory jaw crusher, the ladle furnace slags and the granulated blast furnace slag were ground in a rod mill and afterwards milled in a ball mill to the desired fineness. During crushing and milling in the ball mill the energy input was measured, for the rod mill it was calculated using a known procedure. While comminuting in the ball mill apart from the energy input also the quantity of the mass specific surface was measured in differing steps using the measurement method after Blaine. Apart from the comminution a magnetic separation was carried out with a bar magnet before the following comminution step to determine the portion of present steel. For subsequent investigations different portions of the slags were milled to a fineness of 2000, 4000 and 6000 Blaine. The slags were added in the contents of 12,5%, 25% and for one ladle furnace slag of 50% to so called Einheitszement, to produce mortar prisms for strength testing. These were tested for the initial strength after 7 days and for the standard strength after 28 days. Accompanying these tests was the determination of the young’s modulus through measurements of sound propagation time. The developments of these parameters over time were used to compare the behaviours of the slags. For testing of soundness according to autoclave testing after ÖNORM B 3309-1 also mortar prisms were produced, to which 25% slag was added for all finenesses. Afterwards the testing was carried out for all slags for the finenesses of 4000 and 6000 Blaine with 50% added slag. The tests showed that a beneficiation of ladle furnace slags to an additive and in combination with a cement of the strength class 42,5 yields binders which show strengths in the range of the strength class 32,5 even for high amounts of added slag. Compared to blast furnace slag the strengths measured after 7 days were similar or around 6% lower. After 28 days strengths were measured, which were up to 17% lower for the highest added slag content. The soundness behaviour was compared to the behaviour of granulated blast furnace slag and showed an up to 33% greater change in length compared to blast furnace slag for 50% added slag content, but within the limit for a positive evaluation
Translated title of the contributionInvestigation of the suitability of ladle slags for use as a substitute for blast furnace slag in cements
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Marschall, Irmtraud, Supervisor (internal)
Award date1 Jul 2022
Publication statusPublished - 2022

Bibliographical note

no embargo

Keywords

  • ladle furnace slag
  • LFS
  • slag
  • granulated blast furnace slag

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