Which of the following tests would assess the stability of a compacted aggregate base?

The California Bearing Ratio (CBR) Test is the correct choice for assessing the stability of a compacted aggregate base. This test measures the strength of the material by comparing the pressure required to penetrate a standard piston into the soil to that required for a similar penetration into crushed stone. A higher CBR value indicates better load-bearing capacity and overall stability, which is critical for determining if the compacted aggregate base will adequately support traffic loads without excessive deformation.

The other tests listed serve different purposes. The Marshall Stability Test is primarily used to evaluate asphalt mixtures rather than aggregate bases. The Slump Test measures the workability of fresh concrete and is not relevant to compacted aggregates. The Moisture-Density Relationship helps establish the optimum moisture content for compaction but does not directly assess the stability under load conditions. Thus, the CBR test stands out as the most appropriate method for evaluating the stability of compacted aggregate bases.