Why are my China clay objects breaking during drying?
China clay is or kaolin is not structurally strong enough just on its own and needs to be mixed with other materials to form a more robust material that will survive the pre-firing drying period. Assuming this is happening pre-kiln. When you say " when it is dry after some time they end up broken" it sounds like you may not be firing them soon enough or not at all, which is required for them to remain solid. Otherwise they will return to the dust that they came from.