Slag cement was used because the customer needed a high strength concrete mix that would consistently perform in the summer heat. Using slag, the high strength mix stayed workable longer than a comparable straight cement mix, as well as helped them stay on schedule with their post tension decks. The use of slag cement (30%) granted a strength curve that allowed them to reach the desired strength to put stress on their cables as well as reach the 6000 psi that the mix was designed for in 28 days, consistently.
