What is mass concrete

A question often arises as to exactly what is considered to be mass concrete. According to ACI 116R,1 mass concrete is defined as “any volume of concrete with dimensions large enough to require that measures be taken to cope with generation of heat from hydration of the cement and attendant volume change, to minimize cracking.” Because this definition doesn’t provide a specific measure, many agencies have developed their own definitions of mass concrete. 

For example, mass concrete is defined by some agencies as “any concrete element having a least dimension greater than 3 ft (0.9 m).” Under this definition, a large mat foundation with a thickness of 3 ft (0.9 m) would not be considered mass concrete, but a large mat foundation with a thickness of 3.25 ft (1 m) would be considered mass concrete.

Other agencies use different minimum dimensions, ranging from 1.5 to 6.5 ft (0.46 to 2.0 m), depending on

past experience. Note that none of these definitions considers the cementitious material content of the concrete. Temperatures within a concrete element will be much different if high-performance or high-early-strength concrete is used rather than typical structural concrete.