According to the standard code, the minimum acceptable soil compaction for fill under a structure is _________ percent of maximum density.

The standard code stipulates that the minimum acceptable soil compaction for fill under a structure is 90 percent of maximum density. This level of compaction is critical in ensuring that the foundation of a structure has adequate support and stability. Proper soil compaction reduces the likelihood of settlement and enhances the soil's load-bearing capacity, which is essential for the durability and safety of the construction.

Achieving 90 percent of maximum density indicates that the soil has been sufficiently compacted to minimize air voids and ensure that it can properly support the loads that will be applied to the structure. This is a widely accepted industry standard, and adhering to it is fundamental in construction practices to prevent future structural issues like shifting or sinking.