What is the allowed tolerance for the height of a 6" mold used in standard proctor tests?

In the context of the Standard Proctor Test, which is utilized to determine the optimal moisture content and maximum dry density of soils, the specification for mold height is crucial for ensuring consistent test results. The tolerances for the height of the mold are set to maintain uniformity in the testing process.

The correct tolerance for the height of a 6-inch mold is established as ± .018 inches. This standard ensures that even minor variations in mold height do not significantly impact the volume of soil tested, which could lead to discrepancies in the density results. Maintaining this precise tolerance is vital because it directly influences the calculations and interpretations made from the test results, reflecting the soil's compactability and its behavior under load.

The other tolerances listed do not conform to the standard requirements for this particular test, as they either exceed or do not meet the specified restrictions. Consequently, adhering to the correct mold height tolerance reinforces the reliability and repeatability of the test, ultimately contributing to the overall integrity of the soil testing process.