Bonding durability of polymer-modified concrete repair overlays under freeze-thaw conditions

摘要

One of the main issues associated with the reliability and durability of concrete in cold regions is the effect of freezing and thawing cycles on concrete structures. Polymer-modified concrete (PMC), which consists of Portland cement concrete with a polymer modifier, has advantages of good bonding strength to the substrate concrete, high tensile and flexural strengths, and low shrinkage and permeability. Due to their performance and durability, PMC overlays can be considered as a method of preserving damaged concrete structures. In this research, the durability of PMC overlays bonded to conventional concrete substrates under freeze-thaw cycles was investigated. In total, 25 PMC mix designs for repair overlays were examined. To investigate the effects of the type and amount of polymer and the presence of silica fume, two different types of modifier polymer (based on styrene butadiene rubber (SBR) or acrylic) at different replacement percentages and various amounts of silica fume were considered. For both polymer modifiers, maximum bonding occurred with the addition of 20% polymer by cement weight. The best durability was observed with the addition of 5% silica fume. The SBR-based PMCs showed stronger bonding and better durability than the acrylic-based PMCs.