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I I I I I I I I I I I I I I I I I I I - to be used primarily for destructive testing to minimize the effect of large size aggregate. However~ only two samples with an adequate length (i.e.~ one foot) and with small en~ugh aggregate that would not disproportionately affect the test results were obtained. The core recovery ranged from 70% to 100% and averaged 78% for the six- inch diameter core. Recovery ranged from 40% to 100% and averaged 89% for the NX core. RQD ranged from 15% to 100% and averaged 51% for the six-inch diameter core. RQD ranged from 10% to 85% and averaged 48% for the NX core. Part of the low RQD and recovery percentage can be attributed to the drilling procedures. For example~ fragments of loose hard aggregate rolling around in the bottom of the hole resulted in grinding and pulverizing of the core. This was especially true for the six inch diameter cores. Evidence for this is found in the fact that five thin walled six inch diameter core barrels were destroyed by rolling aggregate. Detailed descriptions of the concrete core are given in Appendix A. In general~ the concrete ranged from poorly cemented to well cemented~ with 30% cement and 70% sand and aggregate. The aggregate was composed of angular gra- nite fragments (crushed) that ranged from well graded to gap graded. Bad sec- tions of concrete in the core were common and included honeycombed areas~ poorly cemented zones~ "rubble filled voids" (void of cement)~ and "unhydrated cement" (powder). Caving of the holes was common. In general~ the bottom 20 feet of concrete between Stations 0+30 and 0+60 was of good to excellent quality. Laboratory Tested Strengths A total of 16 concrete samples were tested for unconfined compressive strength~ density~ and moisture content; seven samples were tested for modulus of elacticity and five samples for tensile strength. The laboratory test results are given in Appendix B. -11-