there is a company in south western virgina that distributes a "natural organic" product that will essentially reverse the chemical reaction between cement and water that creates concrete and should allow you to soften the concrete with minimal damage to steel, painted and aluminum surfaces. i'm a construction manager and i've used this product on a limited basis with moderate success. the company is called socon or southern concrete pumping or something like that. not much help but maybe you can check with someone local to you and find a smiliar product.