Cold-bonded Class-F fly ash aggregate and its application in pervious concrete: An experimental study on effect of single particle gradation

Two single particle gradations were employed to investigate the effect on engineering properties of cold-bonded fly ash aggregate (CBA) in comparison with those of crushed stone (CS) applied in pervious concrete. Cold-bonded fly ash aggregate having two distinct gradations (5–10 mm and 10–12.5 mm) was fabricated from 85% Class-F fly ash, 15% Portland cement, and a water-to-cementitious materials ratio of 20% by using a pelletizer machine and cured in 1-d air, following by fully immersed in 6-d water at 27 ± 2 o C before testing the engineering properties. Engineering properties of pervious concretes with two single-graded CBAs as total CS replacements were examined. Experimental results showed that CBA had inferior engineering properties to CS, resulting in the lower engineering properties of pervious concretes using CBA than those of concretes using CS, regardless of particle gradations. The single particle gradations had minor effect on specific gravity and significant changes in bulk density, water absorption, and crushing value of both CS and CBA. The use of 10–12.5-mm aggregates improved compressive strength by 49.00–61.15% and flexural strength by 7.10–20.09%, and decreased permeability coefficient by 30.84–34.24% of pervious concretes, resulting from the reductions of porosity by 5.93–6.24% and connected void volume by 6.26–15.88%, when compared with that of 5–10-mm aggregates, irrespective of aggregate types. The effect of single particle gradations on the density of pervious concretes was negligible. Consequently, the single particle gradations remarkably affected the engineering properties of CBA and further the performance of pervious concretes using CBA. • Particle gradations significantly influenced engineering properties of CBA. • Particle gradations affected engineering properties of pervious concretes. • Particle gradations had a minor effect on the density of pervious concretes. • Relationships between engineering properties of CBA and concrete were established. • Microstructural models of concrete using CBA with various gradations were explored.