Investigation of the connection between test results found in the laboratory on volume stability and the values found in practice for LD slags

Investigation of the connection between test results found in the laboratory on volume stability and the values found in practice for LD slags

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Commission of the European Communities
technical steel research
Steelmaking
Investigation of the connection
between test results
found in the laboratory ^
on volume stability and the values
found in practice for LD slags Commission of the European Communities
technical steel research
Steelmaking
Investigation of the connection
between test results
found in the laboratory
on volume stability and the values
found in practice for LD slags
L. M. Juckes
British Steel pic
9, Albert Embankment
London SE1 7SN
United Kingdom
Contract No 7210/XA/804
(1.7.1987 to 30.6.1990)
Final report
Directorate-General
PARL EURCP Biblioth.
Science, Research and Development
N.C. EUR 13430 EN 1991 Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 Luxembourg
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on
behalf of then is responsible for the use which might be made of the
following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1991
ISBN 92-826-0566-3 Catalogue number: CD-NA-13430-EN-C
© ECSC-EEC-EAEC, Brussels · Luxembourg, 1991
Printed in Belgium INVESTIGATION OF THE CONNECTION BETWEEN TEST RESULTS FOUND IN
THE LABORATORY ON VOLUME STABILITY AND THE VALUES FOUND IN
PRACTICE FOR LD SLAGS
Final Summary Report
To facilitate the assessment of the suitability of BOS slags for use as aggregates, reliable tests are
required. This need is given additional impetus by the current harmonisation of European
standards on subjects including aggregates.
This project aims to compare the results of the accelerated expansion test with the behaviour of
BOS slag in weathering heaps and as laid in roads. This test has the advantage of measuring the
characteristic of BOS slag which is of most relevance to its use as an aggregate: its capacity to
expand as a result of hydration of the free lime present.
A test panel of BOS slag was laid in the sub-base of a road, and sampled at regular intervals by
drilling. Comparison of these samples with those from weathering heaps or after the accelerated
expansion test suggests that the reactions occurring in the test are closely similar to those
occurring under ambient conditions. Thus the test is a good representation, in a considerably
shorter time, of the natural processes.
Variants on the normal test were also examined. In particular the presence of sodium chloride
exercised a considerable effect on the extent of the reaction. This was itself affected by the
differing effects of water as vapour and liquid on the hydration behaviour of free lime.
— Ill — CONTENTS
Page
1. INTRODUCTION 1
1.1 Objective
1.2 Background
2. SAMPLE SELECTION 2
2.1 Slag Consistency 3
2.2 Compositional Variation
2.3 Chemical Variation 4
2.4 Free Lime And Associated Phases
2.5 Microscopic Examination 5
2.6 Discussion 6
3. ROAD TEST PANEL
3.1 Construction 7
3.2 Sampling 8
3.3 Results
3.4 Microscopy 9'
4. EFFECT OF NaCl AND MgS04 ON EXPANSION TEST RESULTS 10
4.1 Background 1
4.2 Effect ofNaCl During The Expansion Test 10
4.3t Of MgS04 During Then Test1
4.4t of Immersion In Salt Water
5. FINES AND SELF-BINDING COMPOSITE3
5.1 Fines
5.2 Self-Binding Composite4
6. DISCUSSION 1
7. REFERENCES6
TABLES8
FIGURES 3
APPENDIX 57
— V — LIST OF TABLES
1. Mean Monthly BOS Slag Compositions At Works A
2.Chemical Compositions of Individual Slag Samples
3. Free Lime and Related Phases in Slag Samples
4.Mineralogical Compositions of Slag s (Volume Percent)
5. Size Grading of Slag Used in Road Panel
6.Chemical Analysis of Slag Used in Road Panel
7. Free Lime Content of Slag Used in Road Panel
8.Chemical Analyses of Slag Samples From Road Panel, 19/4/1989
9. Hydration and Carbonation of BOS Slag Samples From Test Road Panel
10. Results From Accelerated Expansion Tests on Samples From Test Road Panel
11. Expansion Test Data For Samples Examined
12. Mean Characteristic Values For Expansion Curves
13. Size Analysis of BOS Slag Used For Immersed Weathering Tests
14. Chemical Analyses of BOS Slag Used For Immersed Weathering Tests
15. Results From Accelerated Expansion Tests After Immersion Weathering, Fresh Water
16. s From d n Tests After n , Salt Water
17. Hydration and Carbonation of BOS Slag Samples Weathered in Fresh Water
18. n and n of BOS Slag s d in Salt Water
19. Chemical Analyses of Crusts
20. Hydration and Carbonation of Free Lime in Fine BOS Slag Sample
LIST OF FIGURES
1. Plot of Total Tricalcium Silicate (Tricalcium Silicate Plus Inverted Tricalcium Silicate)
Against CaO/Si02Ratio For the Test Slags
2. Plot of Total Tricalcium Silicate Against Free Lime Content For the Test Slags
3.Plot of Primary Dicalcium Silicate Against CaO/Si02 Ratio For the Test Slags
4. Plot of y m e t Free Lime Content For the Test Slags
5. Particles of MgO (Labelled M), Derived From Refractory Wear, In BOS Slag.
Scale Bar is 100 μιτι
6. Partial Hydration (H) of Dicalcium Silicate in BOS Slag. Scale Bar is 25 pm
7.l n (H) of Tricalcium e in BOS Slag. Scale Bar is 100 pm
8. Lime (L) With Exsolved RO Intergrowth in BOS Slag. Scale Bar is 25 pm
9.Position of Test Panel (P) in Approach Road
10. Section of Road Panel, Showing Position of BOS Slag in the Sub-Base
11. Slag Panel Surrounded by Dolomite in the Sub-Base
12. Entrance Drive With Slag Panel in Place. The Thin (50 mm) Dolomite Upper Sub-Base
and the Bitumen-Bound Road Base Have Already Been Applied on the Far Side
13. Core Drilling Through the Bitumen-Bound Upper Layers of the Road Test Panel
14. Recovering Unbound Sub-Base Material by Hand
15. Shattering of Slag During Heap Weathering. Scale Bar is 100 pm
16. g of Slag, Mainly Along Grain Boundaries, During Accelerated Expansion Test.
Scale Bar is 100 pm
17. Unaltered Free Lime (Dark) Close to the Crust-Lined Surface of a BOS Slag Fragment.
Scale Bar is 100 pm
18. Hydration of Dicalcium Silicate Globules, the Hydrates Preserving the Original Outlines,
in BOS Slag After the Accelerated Expansion Test. Scale Bar is 50 pm
•VII — 19. Hydration of Dicalcium Silicate Globules, the Hydrates Preserving the Original Outlines,
in BOS Slag From the Road Test Panel. Scale Bar is 50 μπι
20. Extensive Breakdown of Dicalcium Silicate Which Formed by the Inversion of Tricalcium
Silicate in BOS Slag from the Road Panel. Scale Bar is 50 pm
21. Carbonate Crust Forming on Surface of the Slag Fragment During Accelerated Expansion
Test. Scale Bar is 100 pm
22. Effect of NaCl Additions on A-Value (Maximum Expansion) in the d
Expansion Test
23. Effect on NaCl on C-Value (Expansion Rate) in the Accelerated Expansion Test
24. Marginal Hydration of Free MgO During Accelerated Expansion Test, in the Presence of
MgS04. Scale Bar is 100 pm
25. BOS Slag After 1 Month Immersion in Fresh Water. Free Lime (Dark) Shows No
Fracturing; Dicalcium Silicate (Grey) Shows Only Limited Marginal Breakdown.
Scale Bar is 50 pm
26. BOS Slag After IMonth Immersion in Salt Water. Dicalcium Silicate Shows Breakdown
at Crystal Margins, Even Deep Within Particles. Scale Bar is 50 pm
27. BOS Slag After 1 Month Immersion in Salt Water. Free Lime Shows a Pattern of
Fractures. (Other Phases Are Out of Focus Because of Differential Etching).
Scale Bar is 50 pm
28. BOS Slag After 1 Month Immersion in Salt Water. Matrix of RO-Phase (Bright) Appears
to be Dissolving Away Around the Globules of Dicalcium Silicate (Grey). Bar is 50 pm
29. Crust Formed During Immersion Weathering of BOS Slag
— VIII —