Recently, polymer-modified mortars have been used for repairing damaged concrete structures, but their adhesive strength to concrete substrates has been variable and the effects of treatments of concrete substrates have not carefully been considered. In this study, the effects of treatments of concrete substrates on the adhesive strength of polymer-modified mortars to the concrete substrates were investigated for two types of concrete substrates with different water permeations, four types of polymer-modified mortars with polymer-cement ratios of 0 and 5%, and a repair mortar. The treated concrete substrates were in the absolutely dry condition, water-saturated and surface-dried condition and primer-coated condition. The polymer-modified mortars were placed on the concrete substrates, and cured at 20°C and 40% (RH). The adhesive strength was measured at 7 and 28 days after placing. As a result, the adhesive strength of the polymer-modified mortars to the concrete substrates with high water permeation was affected by the treatments. The adhesive strength of the polymer-modified mortars to the primer-coated concrete substrates was higher than that to the concrete substrates treated with other methods.
