Final answer:
Second hand masonry units can only be used if they adhere to specified criteria and receive approval from the engineer responsible for the construction project to ensure safety and compliance with standards.
Step-by-step explanation:
The question is about the use of second hand masonry units in construction. Second hand masonry units shall not be used unless they meet the specified criteria and are approved by the engineer overseeing the project. This is to ensure that the structural integrity and design specifications of a building or structure are not compromised. The units must be inspected to meet the required standards for strength, durability, and suitability for the intended use. Without meeting these conditions, second hand masonry units could potentially lead to unsafe building practices and outcomes.
When it comes to masonry units, using second-hand ones can be risky if they do not meet the specified criteria. Masonry units are the building blocks used in construction, such as bricks or concrete blocks. It is important to ensure that they meet the required standards for strength, size, and durability.