I'm planning on doing the same, but noticed that some people had issues with the time it took for the lime to leach out, even though it's relatively small amount of cement. I've read that by using a large amount of potassium salt in the water for it to soak in, it speeds up the leaching and drops the pH to reasonable levels quickly. I haven't tried this yet, but has anyone else here? Or has anyone an opinion on whether this would actually work?