I need advice-My house is a 100 years. The basement is a combination of horse hair, clay, sediment and probably lime with a thin veneer of cement covering much of the walls. When we moved in 2 years ago, there were some cracks in the cement coating but now it had gotten much worse. The Cement is falling off in large pieces and much of the aggregate has dried to a fine powder. Although the bulk of the walls remain I am concerned that this will continue to get worse. Is there a way to seal the aggregate or preserve what is already there?