Long term properties under marine exposure of steel fibre reinforced concrete containing pfa
Tóm tắt
The paper presents results on the long-term mechanical properties and durability under marine exposure of a steel fibre reinforced concrete (SFRC) mix containing pulverized fuel ash (PFA) which was developed for marine applications. The mix was of proportions by weight of PFA:OPC:fine aggregate:coarse aggregate of 0.26:0.74:1.51:0.84 with a water/(OPC+PFA) ratio of 0.4. The resulting cement content of the mix was 435 kg m−3. Theconcrete was reinforced with low-carbon steel, corrosion-resistant (galvanized) or melt-extract (stainless) steel fibres. Prism specimens were cured in the tidal zone at Aberdeen beach, under wet-dry cycles of sea-water spray in the laboratory, in a water-tank in the laboratory and in the laboratory air. The specimens were cured for up to 1200 marine cycles of exposure (640 days) and were tested at regular intervals of age. The paper presents results on long-term compressive strength, flexural strength and energy absorption capacity as measured from the load-deflection curves. The state of corrosion of fibres is also described. The results indicate that fibres embedded within concrete remain free from corrosion under marine exposure. In the case of fibres exposed at the concrete surface during casting, extensive corrosion occurs in low-carbon steel fibres, isolated rust spots appear in corrosion-resistant fibres and no corrosion is evident in melt-extract fibres. This corrosion, however, remains a surface phenomenon and does not penetrate the concrete. The long-term mechanical properties indicate no deterioration due to possible corrosion. In general the compressive strength of concrete increases significantly with fibre reinforcement.Increases in flexural strength and post-cracking ductility due to fibre reinforcement are of the order normally expected of SFRC.
Tài liệu tham khảo
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