What needs to be verified during concrete placement according to special inspection requirements?

During concrete placement, verifying the use of the required design mix is critical because it ensures that the concrete meets the specified strength, durability, and performance criteria outlined in the design documents. The design mix includes the proportions of cement, aggregates, water, and any admixtures, which directly impact the characteristics of the cured concrete. Adhering to the specified mix helps achieve the desired structural performance, particularly under loads and during varying environmental conditions.

Ensuring that the correct design mix is utilized is vital for maintaining the structural integrity and safety of the building. Deviating from the specified mix can lead to weaknesses in the concrete, potentially resulting in future structural failures or non-compliance with building codes. Therefore, special inspections during concrete placement focus on confirming that the right materials and proportions are being used as designated in the design documents, rather than on aspects like the cost of materials, dimensions of forms, or the structural integrity of formwork, which may have different requirements for verification.