The aggregate makes up most of the concrete and expands far less than the paste, which it holds back in proportion to its stiffness. The concrete's CTE combines the two by the rule chosen; the aggregate's rock type matters most.

Temperature and strain readings over any number of heating and cooling steps; the CTE is the slope of strain against temperature.

CTE measured at several ages, each with the specimen's curing temperature. Ages go to equivalent age and α(t_e) = α_∞ + (α₀ − α_∞)·exp(−t_e/τ) is fitted: the high early value of plastic concrete settling to the hardened one.