Upon completion of initial curing, can test specimens be left in their molds and sealed in plastic bags?

Test specimens should not be left in their molds and sealed in plastic bags upon completion of initial curing because this can lead to several issues, primarily related to moisture retention and temperature control. After initial curing, it is critical for the specimens to be exposed to the environment to allow proper hydration and prevent conditions that could cause excessive moisture retention, which can adversely affect the development of strength and durability in the material.

Keeping specimens in molds and sealed can create an environment that traps moisture, leading to issues such as delayed setting times or potential for surface defects. Proper curing involves exposing the specimens to air to facilitate proper evaporation rates and ensure they achieve the intended strength properties. This also allows them to breathe and reduces the risk of future problems associated with excess moisture or inadequate curing conditions.

Therefore, it's essential that after initial curing, specimens are removed from their molds and adequately cured in an environment that allows for optimal hydration and surface conditions.