58 / 2022-03-31 14:15:36

Potential of nano-engineered concrete as a repair material for deteriorated concrete structures

Nano-engineered concrete,Repair material,New-to-old concrete bond strength,Reinforcing mechanisms,Prediction model

A large number of concrete structures cannot reach their design service life due to damage caused by the combined effects of mechanical loads and environmental actions including fatigue, shrinkage, creep, temperature change, freeze-thaw weathering, etc. To prolong their service life, deteriorated concrete structures are generally repaired with new concrete. However, it is estimated that about half of repairs failed, most of which can be attributed to debonding at the new-to-old concrete interfaces. This confirms the importance of reliable bonding between new and old concretes for repairing concrete structures. Thanks to their nano-core effect, nanofillers show great potential to improve the bond between new and old concrete.

Therefore, this study investigated the potential of nano-engineered concrete as a repair material for deteriorated concrete structures. For this purpose, the study characterized bond strength of nano-engineered concrete with old concrete, as well as explored the reinforcing mechanisms and established a prediction model for the bond strength between nano-engineered concrete with old concrete. The results indicated that bond strength between nano-engineered concrete and old concrete can reach 2.85 MPa, which is 0.8 MPa/39.0% higher than that between new concrete without nanofillers and old concrete. The reinforcing mechanisms can be attributed to the enrichment of nanofillers in the new-to-old concrete interface, compacting the interfacial microstructures and connecting hydration products in micropores of old concrete with that in new concrete. In addition, the prediction model proposed based on the above reinforcing mechanisms can accurately describe the relationship of the nanofiller content and the bond strength of nano-engineered concrete with old concrete.

This study demonstrates that nano-engineered concrete is a promising repair material for deteriorated concrete structures due to its strong bond with old concrete. Moreover, the mechanisms and model proposed in this study are beneficial for understanding and controlling the repair behavior of nano-engineered concrete.