If the concrete contains aggregate larger than what is allowed for the slump test, what must be done?

When conducting a slump test, it is essential that the aggregate used falls within specific size limits as outlined in testing standards. The reason sieving the large aggregate is necessary is that the size of the aggregate can significantly affect the test results. If the concrete contains aggregate larger than the allowed size, it can hinder the ability to achieve a consistent slump measurement.

By sieving, the larger particles can be removed to ensure that the remaining aggregate conforms to the testing requirements. This process enables a more accurate assessment of the concrete's workability, which is essential for ensuring quality in construction practices.

In comparison, simply discarding large aggregate, reducing water content, or replacing the affected concrete do not directly resolve the issue of aggregate size that interferes with the slump test, nor do they guarantee that the remaining material will meet the test standards needed for accurate evaluation. Instead, sieving allows for the proper preparation of the concrete mix while adhering closely to the established guidelines for performance evaluation.