I have concrete pieces 10 cm to 10 cm (C60 recipe with 1 water : 3.3 Portland composite cement : 14.4 gravel 0-16 mm with fibre glass reenforcement) which are not especially designed to remain underwater (but will have the usual concrete resistence against water). Will they resolve into a bucket of water within 4 weeks?

I started the process and after some days some pieces have cracks and even fell apart, but I'm not sure if that's just the glass fibre expanding.

I suspect this to work since something has to happen concrete which isn't mixed to remain when constantly under water when put into water permanently and can't imagine anything else than it falling into it's original ingredients (except the concrete having lost it's chemical reaction potential and being dissolved into water).

I realize that it's a lot of effort. It's more of an experiment.

  • 1
    What is "non-waterproof concrete"? Portland cement permanently bonds to water in a chemical reaction that doesn't un-happen when exposed to more water.
    – isherwood
    Jan 4, 2017 at 14:56
  • I corrected this to say concrete which isn't supposed to be under water permanently, but I realized that the problem with water and concrete is more of expansion of hot or freezing water and that special underwater concrete is just "normal" concrete with chemial additives preventing it from floating apart. Jan 4, 2017 at 18:11

2 Answers 2


Concrete chunks will not become a slurry in water in 4 weeks or 4 years or . . . Concrete recycling is evidently dry crushing. http://crushconqld.com.au/what-process-is-used-for-recycling.html


Concrete doesn't "dry", it cures in a chemical reaction. So introducing it to water will not reverse that process. This should be evident from the vast uses of concrete in constant contact with water.

  • It might be that concrete in constant contact with water have special recipes or additives. Jan 4, 2017 at 18:12
  • 1
    Portland cement is "hydraulic" it cures better when moisture is available. Jan 4, 2017 at 18:35

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