Polymer concrete (PC) are used in bridge deck overlays due to its superior durability specifically freeze-thaw and corrosion resistance. The excellent durability of PC is related to its impermeable microstructure and good bond to concrete or steel substrates. However, there is an increasing need to improve PC resistance to crack propagation (fracture toughness) to enhance its fatigue resistance and extend its service life. Researchers showed that objective becomes possible using dispersed chopped synthetic fibers (6-12 mm long). However, this approach was criticized for its dramatic impact on PC flowability. Here we suggest improving fracture toughness of PC using Multi-Walled Carbon Nanotubes (MWCNTs).PC mixes were produced using epoxy and standard aggregate with varying contents of MWCNTs being: 0 (Neat), 0.5, 1.0, 1.5 and 2.0 wt.% by weight of epoxy. Flowability of PC incorporating MWCNTs was tested. The tensile strength of PC incorporating MWCNTs was evaluated using direct tension test. A closed loop notched beam three-point bending test fracture test was used to evaluate fracture toughness of PC. The crack mouth opening displacement (CMOD) clip gage was used to provide feedback. The inverse analysis approach was used to extract the bilinear stress-crack opening displacement relation and calculate the fracture toughness (GF) of PC with and without MWCNTs. It is shown that MWCNTs significantly improves the fracture toughness and toughness of PC without significantly impacting its flowability. Microstructural analysis using Fourier Transform Infrared Analysis (FTIR) of polymer used to produce PC explains the effect of incorporating MWCNTs.

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Polymer concrete (PC) overlays are typically used in infrastructure applications, specifically bridges and parking structures, to provide durable protection to the structural system. However, PC suffers from cracking and crack propagation during its service life mostly due to fatigue. Fatigue cracking of PC results in limiting the service life of PC considerably. Monitoring of fatigue damage in PC can help extend PC service life.In this paper, we demonstrate the possible use of carbon nanotubes to monitor damage initiation and propagation in PC under fatigue loading. PC prisms were produced using epoxy polymer concrete with varying contents of multi-walled carbon nanotubes (MWCNTs). The percolation level of MWCNTs necessary to produce conductive PC was first determined. Fatigue testing using an AASHTO modified test set-up was conducted. Electrical conductivity of PC overlay was continuously measured during fatigue testing. Damage initiation and propagation in PC incorporating MWCNTs overlays can be detected and monitored.