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Description: This full-colored information sheet is targeted to concrete producers and explains the materials and laboratory testing necessary to produce a quality roller-compacted concrete (RCC) mix for pavement applications. It also looks at a number of alternative mix design procedures and types of batching equipment.
While containing the same basic ingredients as conventional concrete – aggregates, water, admixtures, and cementitious materials – producing a roller-compacted concrete (RCC) mix that is durable under traffic applications is greatly different. Because of its dry, stiff consistency and use of dense-graded aggregates, RCC mixes must be made from materials that are carefully selected and correctly proportioned to meet the requirements of the intended pavement project.
All ingredients in a quality RCC mix must meet all respective and applicable ASTM or CSA requirements and must be proportioned according to methods based on 1) concrete consistency testing, 2) the solid suspension model, 3) the optimal paste volume method, or 4) soil compaction testing.
Conducting a moisture-density test to determine the optimum moisture content and maximum density of RCC mixes is important as this information will be used as the target density to which the mix must be compacted in the field (usually 98% of the maximum total density). RCC may be produced in any type of equipment that provides for thorough mixing of all the ingredients including transit mixers, tilt drum mixers, mobile truck mixers, and horizontal shaft mixers. The batch size of RCC will depend on the selected mixing equipment but it is imperative that all ingredients be mixed vigorously in order to evenly distribute the small amount of water present in the mix. In order to produce a quality final product, mixing, transporting, placing, and compaction must be planned precisely so that the rate of RCC production can keep up with the speed of construction at the site.
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