Seacrete

Seacrete, also known as Seament and Sea Cement, or Biorock, is a substance formed by electro-accumulation of minerals dissolved in seawater.

Seacrete samples range in compressive strength from 3720 to 5350 lbf/in² (26 to 37 MPa) – for comparison, the concrete typically used in sidewalks has a strength of about 3500 lbf/in² (24 MPa). With very slow deposition (up to a year or more) strengths as high as 8000 lbf/in² (55 MPa) have been achieved. This is because the material is deposited in a less porous (and thus denser state) when the material is deposited slowly. One of the main component of seacrete is magnesium hydroxide, another is calcium carbonate. This composition is chiefly the result of the ionic composition of seawater.

It has been erroneously reported that one kilowatt hour of electric power will result in the accretion of about 1.9 kg (4.2 lb) of seacrete; unfortunately this value appears to come from a confusion of power with energy and is therefore incorrect by a factor of 42 (the duration of the experiment was 42 hours). Correcting for this, seacrete becomes rather expensive: At $0.05 per kilowatt hour it would cost $1.10/kg, plus the cost of the electrodes (one of which will be embedded within the resulting object).

The production methods used in the original experiment were not optimal, and it is hoped that significantly lower costs will be possible.

External links

References

* Wolf Hilbertz' 1979 paper: Hilbertz, W.H., "Electrodeposition of Minerals in Sea Water: Experiments and Applications," IEEE Journal on Oceanic Engineering, Vol. OE-4, No. 3, pp. 94-113, 1979