A new study published in The Open Civil Engineering Journal by Dr. Chenhui Jiang of the Department of Construction Engineering, Zhejiang College of Construction, Hangzhou, China, takes one of civil engineering's most foundational rules and brings it into the present. Abrams' Law — a relationship between concrete's water-to-cement ratio and its compressive strength, first set out by Duff Abrams in 1918 — has guided concrete mix design for over a century. But as the construction industry has increasingly adopted fly ash, a byproduct of coal-fired power plants, as a partial substitute for Portland cement, the original formula has shown clear limitations. It simply was not designed with such mineral additives in mind, and applying it directly to fly ash concrete can produce inaccurate strength predictions, complicating the design of safe and sustainable structures.