FIELD EVALUATION OF CONCRETE PAVEMENT CONSOLIDATION

For long-term durability of concrete pavements, it is required that the concrete be adequately consolidated. Inadequate consolidation of concrete can result in weak concrete that may lead to premature failure or loss of serviceability of the pavement. Presented in this paper is the result of a comprehensive study on concrete pavement consolidation conducted by the Construction Technology Laboratories, Inc., and sponsored by the Federal Highway Administration. The scope of the work consisted of laboratory testing, evaluation of nuclear gauges, development of model acceptance plans for concrete consolidation, and field implementation of the acceptance plans. In laboratory tests, consolidation was found to have a strong influence on compressive strength, bond of concrete to reinforcing steel, and permeability of concrete. There was a lesser effect of consolidation on resistance to freezing and thawing. A loss of 30 percent was sustained in compressive strength for every 5 percent decrease in consolidation. A variety of nuclear density gauges was evaluated for use in monitoring consolidation of concrete. Information was obtained from literature sources and state highway agencies. Typical precision on field concrete ranges from 1 to 2 lb/cu ft (16 to 32 kg/cu m) for most gauge types. A combination of techniques such as the consolidation monitoring device and commercial direct transmission gauges shows promise as a means of monitoring consolidation during the paving process. A model acceptance sampling plan for concrete consolidation is proposed. The plan is of the inspection-by-variables type and requires a sample size of eight per lot. The plan provides for buyer's and seller's risks of 5 percent. Field trial of a model acceptance plan was carried out along a section of I-86 in Idaho. The field study indicates that it is practical and cost effective to monitor concrete consolidation in the field.