Couple of comments: If the hydrocal is alkaline it will actually tend to reduce corrosion; acid promotes corrosion in steel alkaline recduces it.
ckelloug; in a couple of places in different post you mention pre or post tensioning reducing deflection...are you sure? Deflection depends entirely on Young's modulus, are you modifying the modulus with the tensioning? I thought that all tensioning did was increase yield strength by putting tensile stresses into the tensioning medium instead of relying on the tensile strength of the bulk material.
An open mind is a virtue...so long as all the common sense has not leaked out.