4 ms·

There is also basalt rebar. Last I checked, some building codes allow equivalent 1:1 tradeoff with classic rebar - even though the basalt rebar is stronger. F

There is also basalt rebar. Last I checked, some building codes allow equivalent 1:1 tradeoff with classic rebar - even though the basalt rebar is stronger. From what I understand, basalt rebar does not have the usual problem of regular rebar where oxidizing (rust) expansion can cause cracking in concrete. Additionally, the temperature expansion rates are much closer (rebar vs concrete). My main hesitation would be that it is relatively new so we don't have that much data on how well it ages. Overall, it seems better than rebar classic by far (other than cost - which hasn't been scaled) - but I don't build structures for a living.

SECProto 5y ago
> Last I checked, some building codes allow equivalent 1:1 tradeoff with classic rebar - even though the basalt rebar is stronger. Basalt rebar has a much lower elastic modulus, so when it fails, it fails. Steel on the other hand has a much larger elastic region - where the steel stretches while still carrying the same load. Part of the benefit of reinforced concrete is elastic failure - essentially every (properly) designed reinforced concrete structure is designed to fail with the tensile side of concrete cracking while the steel rebar still caries load, giving visual evidence that the concrete has failed. This is called elastic failure. This works because steel has a large ductile range. Basalt rebar doesn't fail the same way, so substituting it 1:1 seems inappropriate, regardless of it being stronger (per unit area). I did find one random study[1] that substituted basalt rebar 1:1 with steel and compared the failure modes, and found that basalt-reinforced had cracking load essentially the same as a steel-reinforced, but a much larger ultimate load. Interestingly, the higher ultimate strength more than makes up for the much lower elastic modulus. [1] https://www.icontrolpollution.com/articles/investigation-of-structural-members-with-basalt-rebar-reinforcement-as-an-effective-alternative-of-standard-steel-rebar-.pdf https://www.icontrolpollution.com/articles/investigation-of-...

SECProto 5y ago

> Last I checked, some building codes allow equivalent 1:1 tradeoff with classic rebar - even though the basalt rebar is stronger. Basalt rebar has a much lower elastic modulus, so when it fails, it fails. Steel on the other hand has a much larger elastic region - where the steel stretches while still carrying the same load. Part of the benefit of reinforced concrete is elastic failure - essentially every (properly) designed reinforced concrete structure is designed to fail with the tensile side of concrete cracking while the steel rebar still caries load, giving visual evidence that the concrete has failed. This is called elastic failure. This works because steel has a large ductile range. Basalt rebar doesn't fail the same way, so substituting it 1:1 seems inappropriate, regardless of it being stronger (per unit area). I did find one random study[1] that substituted basalt rebar 1:1 with steel and compared the failure modes, and found that basalt-reinforced had cracking load essentially the same as a steel-reinforced, but a much larger ultimate load. Interestingly, the higher ultimate strength more than makes up for the much lower elastic modulus. [1] https://www.icontrolpollution.com/articles/investigation-of-structural-members-with-basalt-rebar-reinforcement-as-an-effective-alternative-of-standard-steel-rebar-.pdf https://www.icontrolpollution.com/articles/investigation-of-...