xxxxxxxxxx
try to use disabled="disabled":
<input type="text" id="txtEditAlternate" class="form-control" name="alternate" disabled="disabled" />
I hope it will work for you.
xxxxxxxxxx
/*sometimes the attribute works, but you just can't see it, especially if it is styled with css
you can try targetting the element with the :disabled pseudo selector in css
*/
.element:disabled{
/*your css rule*/
}