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Assumptions
Building Process exists
Waterproofing is able to be replaced

Notes

  • Please answer yes or no with the science backing.

  • This question is only about the strength and lifespan.

  • This question is NOT about cost, or process.

  • Additional material may be required. Please include in your answer if it can overcome an obstacle.

Potentially Relevant Values

Compressive Strengths:
Granite: ~200MPa
Concrete: ~70MPa

Dev Slocum
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    What have you researched / found so far? So we don’t repeat and waste effort, ie we make a suggestion then you torpedo us with “I considered that but...”... – Solar Mike Mar 01 '19 at 05:09
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    I suggest you research how tunnels are actually built (there's more than one way of course), then the advanteges of concrete become more apparent. – mart Mar 01 '19 at 07:57
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    How waterproof does this tunnel need to be? (The joints between granite blocks is a critical point.) – ingenørd Mar 01 '19 at 09:11
  • Welcome to Engineering! This looks like a ['Novel Idea' question](http://meta.engineering.stackexchange.com/q/311/1832). Such questions tend to become moving targets and lead to discussions, neither of which are a good fit for our format. See if you can [edit] your question to make it specific and answerable. – Wasabi Mar 01 '19 at 13:16
  • Related: https://worldbuilding.stackexchange.com/q/140188 –  Mar 01 '19 at 13:45
  • @GlenH7 I asked the question on worldbuilding and they referred me here lol. – Dev Slocum Mar 02 '19 at 03:57
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    If your interest lies in increasing service life, the questions you might want to back up and tackle first are (1) what factors currently determine tunnel service life? (2) Does granite actually improve any of these considerations/conditions? Seems a bit like you’re diving into analyzing the bark before determining whether you’re even in the right forest. – CableStay Mar 02 '19 at 13:15
  • Your recent edit has made this question an even better fit for the "Novel Idea" category which as I said make this question a poor fit for this site. Also, pay attention to @CableStay's comment, which raises very valid points. – Wasabi Mar 02 '19 at 15:40
  • @CableStay from my understanding the steel corrodes and the concrete cracks. – Dev Slocum Mar 03 '19 at 03:24

1 Answers1

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It is possible to use granite instead of concrete in construction (remember that buildings were made out of stone long before concrete was invented), but only in those instances where the structure is guaranteed to never experience tensile stresses.

By reinforcing the concrete with prestressed steel rods, it is possible to render the resulting structure resistant to tensile loads as well- something which cannot be done with granite blocks.

Careful preparation of concrete results in uniform properties. Blocks of granite, being natural products mined out of the earth's crust, can possess faults, cracks and inhomogenieties which compromise their structural integrity in a way that is out of the designer's control.

I know of no way to reinforce granite blocks with any sort of nanomaterials.

niels nielsen
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  • Concrete can also have non-uniform properties, mixing issues, filling times etc - it may not be the “perfect” material... – Solar Mike Mar 01 '19 at 06:25
  • yeah, so a good batch has to be carefully prepared, if the resulting structure is to be sound. – niels nielsen Mar 01 '19 at 06:31
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    low quality question. – kamran Mar 01 '19 at 08:25
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    but a suitable answer, yes? – niels nielsen Mar 01 '19 at 18:52
  • @nielsnielsen great answer! regarding the reinforcing the granite: there may be opportunity to reinforce the granite with prestressed cords or outer layer of a high yield strength material such as graphene. – Dev Slocum Mar 02 '19 at 04:02
  • @kamran I have tried to make the question better – Dev Slocum Mar 02 '19 at 04:04
  • @nielsnielsen regarding the lack of uniform material: I have added a quality control stage to the question though I recognize we cannot properly test the blocks without destroying them. We may be able to mitigate the damages when poor quality ones fail by using smaller blocks. Essentially replacing a brick – Dev Slocum Mar 02 '19 at 04:15
  • Oh no, you can indeed test the granite blocks via CATscan/xray or ultrasonic imaging, but this results in a lot of $$$ invested in each block. Is it worth it? – niels nielsen Mar 02 '19 at 06:21
  • @nielsnielsen eh thats cool. I am not asking about whether it is cheap or affordable. I am asking if it would be at least as strong and longer lasting. – Dev Slocum Mar 03 '19 at 03:56