follows placing and consolidating the plastic concrete. Hydration continues indefinitely at a decreasing rate as
long as the mixture contains water and the temperature conditions are favorable. Once the water is removed,
hydration ceases and cannot be restarted.
is the period
of time from consolidation
to the point when
the concrete reaches its
design strength. During
this period, you must take certain steps to keep the concrete moist and as near to 73F as practicable. The
properties of concrete, such as freeze and thaw resistance, strength, watertightness, wear resistance, and volume
stability, cure or improve with age as long as you maintain the moisture and temperature conditions favorable to
Length of Curing Period
The length of time that you must protect concrete against moisture loss depends on the type of cement used, mix
proportions, required strength, size and shape of the concrete mass, weather, and future exposure conditions. The
period can vary from a few days to a month or longer. For most structural use, the curing period for cast-in-lace
concrete is usually 3 days to 2 weeks, depending on conditions such as temperature, cement type, and mix
proportions. Bridge decks and other slabs exposed to weather and chemical attack usually require more extended
curing periods. Figure 4-12 shows how moist curing affects the compressive strength of concrete.
Figure 4-12. Moist curing effect on compressive strength of concrete.