Second-hand masonry units that are reused must be:

Reusing second-hand masonry units in construction involves several key considerations to ensure structural integrity and safety. Each criterion mentioned contributes to the overall quality and longevity of the reused material.

Units must be in whole, sound material because this ensures they can withstand the stresses and loads they will encounter in the building. Any chips, breaks, or missing pieces could compromise the structure's stability.

Being free of cracks is equally important. Cracks can indicate internal weaknesses or past failures that could lead to further degradation over time or cause the masonry to fail under load.

Cleaning the units of old mortar is vital for proper bonding with new mortar. Residual mortar can create weak points where the new material does not adhere well, leading to structural failures.

When all these factors are considered collectively, the correct approach is to ensure that reused masonry units satisfy all these conditions. This comprehensive assessment makes the reused units suitable for construction, promoting safety and reliability in the building process.