The findings of extensive laboratory tests are reported and specifications for compaction control of granular bases and subbases are presented. Major emphasis during the early states of the research was placed on accumlation and analysis of information on current practices of state highway departments. The laboratory test program involved seven methods of compaction and four materials under various moisture conditions and gradations. A prototype field compaction testing program was conducted using the same four aggregates. The materials were compacted under simulated field conditions over two different subgrades in test pits. The density was interpreted as representing the maximum compaction obtainable in the field. The purpose of these tests was to determine correlations between laboratory and field densities, and to evaluate the current and proposed density standards. Information from a review of literature and current practice was combined with analysis of data from the testing program to produce a set of revised procedures for the control of compaction during construction of granular bases and subbases. This includes test methods for determining maximum laboratory densities, criteria for arriving at target construction densities, and procedures for field control of compaction. More detailed test results and descriptions of the compaction test methods and equipment are contained in the nchrp's final report. The testing program, compaction test results and comparison with test pit density are outlined here, as are also, the field use applications. Conclusions based on the findings are presented. (Author/publisher)
Samenvatting