An Investigation on In-situ Strength and Bonding Strength of Polymer Modified Concretes (PMC) as Repair Overlays on Conventional Concrete Substrate

Polymer modified concrete (PMC) consists of Portland cement concrete with a polymer modifier. Its advantages are proper bonding strength to substrate concrete, high tensile and flexural strength and low amount of shrinkage and permeability. Using PMC overlays can be considered as a method for preservation of damaged concrete structures due to their suitable performance and durability. In this research, 24 mix designs of polymer modified concrete as the repair overlay containing two different types of modifier polymers (Styrene butadiene rubber (SBR)-based and Acrylic-based polymers) with different replacement percentages and various amounts of silica fume was considered to investigate the effect of type and amount of polymers and also presence of silica fume. The in-situ strengths are obtained by the Pull-off Method in different conditions of presence of cores and without cores on cubic samples and without cores on repair overlays. The bonding strength of repair overlays to the substrate is also assessed and a formula is presented for prediction of bonding strength and in-situ strength by consideration mechanical properties.In both polymer modifiers, maximum bonding occurred in the presence of polymer with 20% of cement weight. SBR-based PMC showed stronger bonding compared to the Acrylic-based PMC.