I currently have an existing concrete patio and driveway that has been thier for about 20 years. It has a lot of cracks and pits where you can see the aggregate. I don't want to completely demo and pour another, becasue it will be too costly. How can I repair my existing driveway and patio. I did a lot of exterior improvements to the house and now the driveway and patio are an eye sore. Please help.