Concrete Stone Casting. Pre mixed bags of ready to mix concrete

You can buy premixed bags of readytomix concrete. These simply require water and mixing; the measuring is already done for you. An 80 lb bag (on average) will make 4 sq. feet x 2. 5 thick. A more economical method is to make your own concrete, using this simple timetested formula as a guide 1:2:3 parts by dry volume one part Portland cement, two parts sand, three parts coarse aggregate.