Converting raw materials into the products–Road base material stabilized with slag-based binders
|Organizations:||University of Oulu, Faculty of Technology, Department of Process and Environmental Engineering
|Online Access:||PDF Full Text (PDF, 1.5 MB)|
|Persistent link:|| http://urn.fi/urn:isbn:9514272528
|Publish Date:|| 2004-02-13
|Thesis type:||Doctoral Dissertation
|Defence Note:||Academic Dissertation to be presented with the assent of the Faculty of Technology, University of Oulu, for public discussion in Kajaaninsali (Auditorium L6), Linnanmaa, on February 13th, 2004, at 12 noon.
Professor Asko Saarela
Professor Markku Tammirinne
A procedure is defined for commercializing slags arising as by-products of steelmaking, and this is used to develop certain products. The outcome of the present work comprised three products or groups of products: 1) slag-based binding agents, 2) a road structure improved by means of stabilization with such binding agents, and 3) a procedure for designing stabilized structures. The commercialization procedure was drawn up by examining the technical properties of the initial materials, excluding environmental acceptability and the mechanisms of their chemical reactions.
The research proceeded in stages, of which the first was a reconsideration of the results presented in the author's licentiate thesis concerning factors affecting the stabilization of road construction aggregates with blast-furnace slag-based binding agents and their significance. This was followed by a series of experiments designed to test the validity of these results. At the third stage the selection of slag-based binding agents was extended to include LD steel slag products, while the final stage consisted of the implementation of a set of test structures and associated preliminary experiments and monitoring measurements.
The binding properties of three blast-furnace slag products and three LD steel slag products, used separately or in various combinations, were examined in the course of this work, taking cement as a reference material. Materials were then eliminated as the research proceeded, either on account of their poor binding properties or on economic grounds. The final construction experiments were performed with three combinations: cement-activated granulated blast-furnace slag, LD steel slag-activated granulated blast-furnace slag and a mixture of ground granulated blast-furnace slag and cement.
The actual novel product among the slag-based binding agents to be introduced here is LD steel slag-activated granulated blast-furnace slag, which was found to be similar in its technical properties to cement-activated granulated blast-furnace slag. Structural layers stabilized with these two binding agents showed very similar bearing capacities, although the former did not reach the same compression strengths at an age of 91 days. The reasons for these similarities lay in a larger amount of binding agent used when activated with LD steel slag and the greater thickness of the stabilized layer, factors which both tended to compensate for the poorer compression strength.
The new information gained on the properties of cement-activated granulated blast-furnace slag and the mixture of ground granulated blast-furnace slag and cement opens up fresh opportunities for selecting binding agents and designing road structures. Formulae were developed here for predicting the uniaxial compression strength at 91 days, used as a stabilization criterion, from the value for a sample taken at 28 days, a technique which will speed up the assessment of stabilization results, especially when using slowly reacting slag-based binding agents.
Acta Universitatis Ouluensis. C, Technica
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