Unveiling the Potential of Pretreated Recycled Aggregates and Alkali-Activated Binders in the Development of Pavement-Quality Concrete

As the construction industry faces growing environmental concerns and a need for viable practices, this study explores the potential for substituting natural aggregates (NA) with untreated coarse recycled aggregates (CRAs) and pretreated CRAs (PCRAs) in the production of pavement-quality concrete (PQC). The research explores the performance of ambient-cured alkali-activated pavement-quality concrete (AAPQC), chosen as an environmentally friendly alternative to the water cured cement concrete, with the CRAs as the alternative to the traditional NA. The investigation includes a systematic assessment of the properties of PCRAs to determine their suitability for AAPQC production. Furthermore, a series of experimental investigations such as slump, ultrasonic pulse velocity, compressive strength, flexural strength, split tensile strength, water absorption, apparent density, and the volume of permeable voids to evaluate the mechanical and durability properties of the AAPQC mixtures were carried out. Microstructural investigations including FESEM, energy-dispersive X-ray, X-ray diffraction, FTIR, and stereo microscopy were also carried out for deeper understanding and substantiation of the results observed. It was interesting to observe that AAPQC with 100% PCRAs exhibited higher compressive strength (approximately 55.1 MPa) and flexural strength (4.9 MPa) than AAPQC with 100% untreated CRAs. Furthermore, AAPQCs with 100% PCRAs were superior in absorption and permeability compared to AAPQCs with CRAs. With these and many more interesting observations, this study holds promise and contributes valuable insights into viable pavement construction practices by promoting the use of PCRAs in the ambient-cured AAPQC.