After how many hours should molds be removed from specimens that are not to be transported?

In materials engineering, particularly when dealing with the curing and setting process of concrete or similar materials, it is crucial to ensure that molds are removed at the appropriate time to optimize the quality of the specimens. Removing molds too early can result in damage or deformation of the specimen because it may not have reached sufficient strength.

Typically, molds should remain in place for at least 24 hours to allow the material to cure adequately, which helps develop the necessary hardness and stability. This period allows the chemical processes of setting and hydration to proceed to a point where the specimen can sustain itself without the support of the mold. After 24 hours, specimens can usually be safely demolded without compromising their integrity.

The option indicating a period longer than 24 hours may ensure even greater strength but is not a standard practice for the immediate removal of molds that are not intended for transportation. The approach of removing molds after 24 hours aligns with industry standards, effectively balancing the time it takes to develop the necessary mechanical properties while maintaining efficiency in the testing or production process.