Characterization Of Cemented And Fiber-reinforced RAP Aggregate Materials For Base/ Sub-base Applications




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Civil & Environmental Engineering


The engineering product known as RAP is a bonded base and sub-base material produced by the process of blending crushed recycled construction and demolition waste and debris to specified gradation requirements, and by bonding these with a fine silica Portland cement matrix at optimum moisture for compaction density. RAP has a great potential as an economically, environmentally, and structurally sound alternative to non-bonded materials conventionally used for base/sub-base applications in pavement engineering. The present work is aimed at thoroughly testing the engineering properties of RAP product in order to assess its suitability as a structurally sound and environmentally safe material, as well as to maintain high standards in its production process and field applications. In order to accomplish this goal, a comprehensive series of basic and engineering tests were conducted on compacted RAP specimens at the UTA geotechnical and geo-environmental laboratories. RAP specimens with no fibers (control specimens) were tested at 0, 2, and 4% dosage levels of Portland cement. RAP specimens with fibers (fiber-reinforced) were tested at 2, 4, and 6% dosage levels of Portland cement.Basic testing included gradation, specific gravity, Atterberg limits, and standard Proctor compaction tests. Engineering testing included permeability, leaching, unconfined compression, and small-strain shear modulus tests. The latter was accomplished via fixed-free resonant column testing for a purely qualitative analysis of RAP stiffness response. Leaching tests included pH, total and volatile dissolved solids, total and volatile suspended solids, and turbidity. Most tests were conducted as per current Texas Department of Transportation’s (TxDOT) standard test methods. Engineering test results on control and fiber-reinforced RAP materials were then compared to those reported in the literature for similar reclaimed asphalt pavement (RAP) materials. Results confirmed the potential of RAP material as an environmentally and structurally sound alternative to non-bonded materials for base/sub-base construction purposes.