| EPSRC Reference: |
GR/M97510/01 |
| Title: |
THAUMASITE FORMATION BY COMBINED ACID & SULFATE ATTACK OF CONCRETE |
| Principal Investigator: |
Byars, Dr E |
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| Department: |
Civil and Structural Engineering |
| Organisation: |
University of Sheffield |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
01 January 2000 |
Ends: |
30 June 2003 |
Value (£): |
208,861
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| EPSRC Research Topic Classifications: |
| Civil Engineering Materials |
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| EPSRC Industrial Sector Classifications: |
| Construction |
Transport Systems and Vehicles |
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Summary on Grant Application Form |
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This proposal addresses thaumasite attack of concrete which has relevance due to the discovery of thaumasite attack in the foundations of M5 motorway concrete bridges, constructed in a backfill of Lower Lias clay.Thaumasite may be formed as a result of neutral sulfate attack. However Lower Lias clay contains pyrites which oxidises after excavation to form ferrous/ferric oxide and sulfuric acid. Neutralisation by reaction with clay and concrete surfaces increases sulfate ground water levels due to the formation of calcium, soidum and magnesium sulfate salts. It follows that pyritic clay aggressivity is significantly different before and after excavation, in terms of both acidity and sulphate content.The mechanisms responsible for thaumasite formation in acidic/sulfate conditions are not fully understood and this has been acknowledged in the recent Experts' Report on the M5 bridge problem.This investigation will examine concrete deterioration in sulfate, acidic and acidic/sulfate solutions. Also, the chemical changes in pyritic clay during simulated excavation and backfill cycles will be measured to provide the information necessary to make informed specification of concrete in those conditions and to recommend aggressivity-testing procedures for pyritic clays.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.shef.ac.uk |