Performance of Continuously Reinforced Concrete Pavement Containing Recycled Concrete Aggregate

In 1995, the Texas Department of Transportation (TxDOT) began reconstruction in Houston on a section of IH-10 with continuously reinforced concrete pavement (CRCP). The unique aspect of this project was the use of crushed concrete as both coarse and fine aggregates in the new concrete. No virgin aggregates were used. The primary objectives of this study were to evaluate (1) the material properties of recycled concrete aggregate (RCA), (2) their effect on paving operations, and (3) in-situ concrete properties to identify the reasons for good pavement performance. The properties of recycled aggregate measured in this study compared with virgin aggregate are consistent with those reported elsewhere: low specific gravity, higher water absorption, sulfate soundness loss, LA abrasion loss, and thermal coefficient. Little variation was observed in the paving operation due to the use of 100 % recycled coarse and fine aggregates. The moisture control of recycled aggregate, especially fine aggregate, is critical in producing consistent and workable concrete. The performance of the reconstructed CRCP has been excellent, with tight crack widths and little spalling. Between concrete with virgin aggregates and concrete with recycled aggregates, there is no significant difference in thermal coefficient and permeability; however, there are significant differences in modulus of elasticity, compressive and indirect tensile strength, and water absorption. The low modulus of RCA concrete and good bond between recycled coarse aggregates and new mortar appear to be the key ingredients for good pavement performance.