What must be done if a new mix design contains materials not noted in the project specifications?

When a new mix design includes materials that are not specified in the project documentation, it is essential to conduct trial mixes. This step is crucial because trial mixes allow for the assessment of the new materials' compatibility and performance within the concrete. By running these tests, engineers can determine how the new components affect the workability, strength, durability, and overall quality of the concrete mix.

Trial mixes can help in optimizing the mix design by providing practical insights into how the new materials interact with the existing components. This process ensures that the concrete produced meets the necessary performance standards and project requirements before it is used in actual construction. Conducting trial mixes also helps in mitigating risks associated with untested materials and provides the necessary data to inform decisions regarding potential revisions to the mix design.

In contrast, simply mixing without trial testing would not provide the necessary evaluation or assurance that the new materials are appropriate for use. Confirming and documenting changes is essential for record-keeping but does not adequately address the implications of a new mix design on concrete performance. Updating project specifications may be necessary after trials, but it should follow the testing process to ensure that the specifications reflect the mix's capabilities.