Improving Fracture Toughness of Polymer Concrete Using MWCNTs

Abstract

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.

Evaluation of fracture toughness properties of polymer concrete composite using deep learning approach

“…35 Besides, incorporating a nanofiller can significantly increase the CTOD. Such an observation is in good agreement with the experimental investigation of Douba 5 and Emiroglu et al 35 Based on the PDP curves of X 5 , the inclusion of fiber has a considerable effect on the K Ic . The optimum amount of fiber in the PC is about 1 to 1. is consistent with experimental investigations reported in.…”

“…It was confirmed in some investigations on the PC 34 . Based on the PDP analysis of X 2 , increasing the aggregate wt% increases the CTOD and the optimum CTOD can be achieved by adding about 79 wt% aggregates as reported in Douba 5 …”

“…34 Based on the PDP analysis of X 2 , increasing the aggregate wt% increases the CTOD and the optimum CTOD can be achieved by adding about 79 wt% aggregates as reported in Douba. 5 The PDP curve of X 3 exhibits that the K Ic increases by increasing the aggregate size. This finding is in good agreement with the experimental investigation in Asdollah-Tabar et al 32 Increasing the X 3 variable causes a sharp decrease in the CTOD.…”

“…The quasi-brittle materials show moderate strain hardening prior to attaining ultimate stress or show significant softening post peak stress. 5 Therefore, the quasi-brittle fracture mechanics (QBFM) approach using the effective elastic crack modulus theory is used to evaluate their fracture properties. The Two-Parameter Method (TPM), which is a direct method for calculating the K Ic and CTOD, is frequently implemented for PCs.…”

“…Due to the high ductility and nonlinear behavior, PCs are considered quasi‐brittle materials. The quasi‐brittle materials show moderate strain hardening prior to attaining ultimate stress or show significant softening post peak stress 5 . Therefore, the quasi‐brittle fracture mechanics (QBFM) approach using the effective elastic crack modulus theory is used to evaluate their fracture properties.…”