Effects of types and replacement levels of artificial fly ash aggregate on physical-mechanical properties, clogging resistance, and microstructure of pervious concrete

• Crushed and cold-bonded fly ash aggregates (CFA and CBA, respectively) were made. • CBA slightly increased permeability of pervious concrete as compared to CFA. • CFA improved mechanical strengths of pervious concrete as compared to CBA. • CBA enhanced clogging resistance of pervious concrete as compared to CFA. • High replacement levels of CFA or CBA remarkably affected the concrete performance. Aggregates are one of main components significantly affecting pervious concrete performance. This study uniquely explored the effects of types and replacement levels of artificial fly ash aggregate (AFA) on physical-mechanical properties, clogging resistance, and microstructure of pervious concrete to facilitate further applications of sustainable pervious concrete using various AFAs. Two types of AFA having various shapes were made from different production technologies, including crushed AFA (CFA) having rough and angular shape and cold-bonded AFA (CBA) having smooth and spherical shape. Three replacement levels of natural crushed stone (CS) by AFA were 0%, 50%, and 100% for producing the pervious concretes. Experimental results exhibited that the use of CFA having rough and angular shape decreased the porosity by 2.18–3.86% and permeability coefficients by 4.77–8.80%, while increasing the compressive strength by 7.24–25.93% and flexural strength by 4.52–33.33%, when compared with that of CBA having smooth and spherical shape, irrespective of aggregate replacement levels. Meanwhile, the use of CBA having smooth and spherical shape enhanced the clogging resistance of pervious concretes as compared to that of CFA having rough and angular shape, regardless of sediment types. High replacement levels of AFAs significantly affected the pervious concrete performance. These findings clearly revealed that the AFA types having various shapes and replacement levels had remarkable effects on physical-mechanical properties, clogging resistance, and microstructure corresponding to pervious concretes, suggesting practical guidance for further applications of permeable and structural pervious concretes using AFA types having various shapes.