Answer: "Annabelle" hydrangea is a named variety of Hydrangea arborescens, or Smooth Hydrangea, which makes large white flowers. It grows best in partial shade in a rich, well-drained yet moist soil and tolerates a wide range of pH. As far as the dieback goes, it's difficult to say without seeing the plants. Certainly cut off any truly dead wood, but be very patient because this plant can leaf out of outwardly looking dead stems. It may have simply suffered from a cold snap and/or transplant shock. (If it came out of a greenhouse for instance and was planted directly outside without any conditioning or acclimating, this could be the case.)
Based on your description I am not sure exactly what happened, but one common cause for wilting is lack of water. Hydrangeas appreciate ample water, especially when newly planted, and also like a soil rich in organic matter. Finally, it is a good idea to mulch them to help maintain soil moisture. They will do best in moist yet well-drained (not soggy) soil.
Another possibility is that by adding the aluminum sulphate and lime you took the pH to an extreme level and/or "burned" the roots in the process. Although "Annabelle" is always white, some hydrangeas, notably those in the Hydrangea macrophylla or Bigleaf Hydrangea group will change color somewhat depending on soil pH, with blue being predominant on acid soil (say 5.0 to 5.5) and pink on a more alkaline soil (say 6.0 to 6.5). If you think you need to adjust your soil you need to run some basic tests to determine where it is already, and then add amendments accordingly. Your County Extension (885-8995) can help you with the tests and with interpreting the results.
In any case, "Annabelle" is a fairly resiliant plant, so it is possible it will resprout from the roots if you make sure it recieves adequate water. It also blooms on new wood, so it would still bloom for you this year if it does resprout. If you suspect you may have added too much aluminum sulfate or lime, the best thing to do would be to dig up and move the plants to fresh soil, keep them watered and see if they pull through.
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