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Basalt fibre reinforced concrete looks promising. The tensile strength is greater than steel rebar, and inexpensive when compared to carbon fibre. The environme

by gnode 7y ago

Basalt fibre reinforced concrete looks promising. The tensile strength is greater than steel rebar, and inexpensive when compared to carbon fibre. The environmental impact is much lower, as it's a melting process similar to fibreglass production, rather than smelting. I get the impression that the continued use of steel rebar is less because there aren't superior technical solutions, but because there are significant regulatory, training and qualification hurdles. Use of non-steel rebars seems to complicate projects, and is only justifiable in special situations. Steel is usually adequate when appropriate anti-corrosion measures are taken (such as coating the rebar in epoxy).

MertsA 7y ago
>such as coating the rebar in epoxy Actually epoxy coated rebar has pretty major debonding issues in practice. If the epoxy coating was continuous then sure, but realistically during bending, cutting, tying, etc you're basically guaranteed to introduce scratches through that thin epoxy layer and once that steel starts rusting it'll tend to spread under the surface causing more cracks in the epoxy and allowing more corrosion. The abstract of this report shows that epoxy coated rebar performs rather poorly. http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r16%20.pdf http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r... >Adhesion loss of the epoxy coating to the steel surface was detected in all but one deck that was 4 years old and older. The epoxy coatings were debonding from the reinforcing bars. Whereas a bonded coating can be expected to protect the steel, a debonded coating allows chlorides, moisture, and oxygen to reach the steel and initiate a rapid corrosion mechanism. Reinforcing bars in various stages of adhesion loss showed visible signs of a corrosion process underneath the coating, suggesting that ECR will provide little or no additional service life for concrete bridge decks in comparison to bare steel. Other systems that will provide longer protection against chloride-induced corrosion of the reinforcing steel with a higher degree of reliability should be considered.

by gnode 7y ago

MertsA 7y ago

>such as coating the rebar in epoxy Actually epoxy coated rebar has pretty major debonding issues in practice. If the epoxy coating was continuous then sure, but realistically during bending, cutting, tying, etc you're basically guaranteed to introduce scratches through that thin epoxy layer and once that steel starts rusting it'll tend to spread under the surface causing more cracks in the epoxy and allowing more corrosion. The abstract of this report shows that epoxy coated rebar performs rather poorly. http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r16%20.pdf http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r... >Adhesion loss of the epoxy coating to the steel surface was detected in all but one deck that was 4 years old and older. The epoxy coatings were debonding from the reinforcing bars. Whereas a bonded coating can be expected to protect the steel, a debonded coating allows chlorides, moisture, and oxygen to reach the steel and initiate a rapid corrosion mechanism. Reinforcing bars in various stages of adhesion loss showed visible signs of a corrosion process underneath the coating, suggesting that ECR will provide little or no additional service life for concrete bridge decks in comparison to bare steel. Other systems that will provide longer protection against chloride-induced corrosion of the reinforcing steel with a higher degree of reliability should be considered.