The Portland Cement Association SRI study measured the solar reflectance of 45 concrete mixes in accordance with ASTM C 1549, Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer. These concretes were selected because they represent the range of concrete and concrete constituents typically used in exterior flat work in the U.S.
After the typical mix designs were tested, researchers created a mix with the darkest of each ingredient (cement, sand, aggregates and fly-ash) to test in a worst case scenario. Read more about the results.