Method-Dependent Bond Strength of Thin-Bed Mortars with Coded Modifiers on Autoclaved Aerated Concrete

This study reanalyzes the tensile bond of white-cement thin-bed mortar joints with a measured thickness of 1 mm in autoclaved aerated concrete (AAC), using axial core tension, the EN 1052-5 bond-wrench method, and companion hardened-mortar tests. Individual observations are summarized descriptively alongside exploratory formulation-mean models. For 94 mm cores, mixture C (0.229 wt.%) had the highest axial mean (0.528 ± 0.081 MPa; n = 4), versus 0.378 ± 0.065 MPa for the reference (n = 5). Mixture A had a low axial mean (0.139 ± 0.123 MPa) but the largest bond-wrench mean (0.351 MPa), demonstrating method-dependent rankings. The available product card for the C-coded powder describes it only as a re-dispersible synthetic-resin powder; the remaining modifiers are known only from broad recorded labels. Water carried by liquid O was included in the total mixing-water dose of 5.75 L per 25 kg of dry base mortar; however, its separate amount was not recorded. The 94 mm bonded area was 2.92 times that of the preliminary 55 mm cores, whose high scatter and unresolved data inconsistency preclude comparison. One wrench assembly was tested per mixture; incomplete fresh-state and conditioning records constrain inference. The study provides a method-aware comparison for this specific thin AAC joint without claiming novelty with respect to AAC bond research.