Effect of hydrophobic admixture and recycled aggregate on physical–mechanical properties and durability aspects of no-fines concrete

No-fines concrete with a compressive strength in the range 7–30 MPa at 28 days of curing were optimized by changing the water/cement ratio from 0.41 to 0.34 and the aggregate/cement ratio from 8 to 4. Some mixtures were also repeated with the addition of a hydrophobic admixture and prepared by fully replacing the ordinary aggregate with recycled aggregate to evaluate durability effects. High susceptibility to carbonation was observed for all the no-fines mixes studied. The use of recycled aggregate increases capillary water absorption (about 50%); however, the related decrease in durability could be easily counteracted with the use of a hydrophobic admixture.