Treatment with nano-silica and bacteria to restore the reduced bond strength between concrete and repair mortar caused by aggressive removal techniques

Removal of degraded concrete during repair activities might have a detrimental impact on the bond strength between and mortar. This research aims to improve bonding in case aggressive removal techniques were used, by singular combined application bacterially induced CaCO3 colloidal nano-silica (CNS) treatments. Water jetting (WJ) jackhammering (JH) compared treatments performed substrates prepared with technique causing lowest bonding. Pull-off test results crushed stone (CC) showed that JH possessed WJ unprepared substrates. To assure reported are reproducible, pull-off tests also another type concrete, gravel (GC). The both cases JH-substrates achieved lower than unprepared- WJ-substrates. reduced was restored CNS treatment irrespective composition. Regarding biodeposition treatment, spraying be superior pouring technique. Microstructural analysis confirmed survival bacteria carbonate precipitation. Porosity substrate surfaces studied capillary absorption, water absorption (including gravity effect) vacuum tests. reduction initial uptake CNS-treated samples evidenced precipitation silica gel at superficial layer substrate. efficacy Energy Dispersive X-Ray Analysis (EDX) recognize interlayer layered composites monolithic structure observed.