Impact of crumb rubber particles on the fracture parameters of concrete through WFM, SEM and BEM

Abstract

Fracture parameters and cracking behavior of concrete are the most important factors influencing the fracture mechanism of concrete structures. The use of lightweight and recycled materials such as crumb rubber due to their unknown behavior can change fracture parameters and cracking behavior of concrete. The present study focused on the fracture behavior of notched beams containing crumb rubber. For this purpose, fine aggregates were substituted by crumb rubber in 4 different contents (5, 10, 15 and 20% by volume of fine aggregates). Fracture parameters were achieved through Work of Fracture Method (WFM), Size Effect Method (SEM) and Boundary Effect Method (BEM). Based on the obtained results, by rising crumb rubber percentage up to 20%, the initial fracture energy (Gf), the length of the fracture process zone (Cf) and the fracture toughness (KIC) in SEM and the total fracture energy (GF) and the characteristic length (Lch) in WFM increased, while the brittleness number (β) in SEM decreased. Furthermore, the results depicted that for concrete containing crumb rubber, the GF/Gf ratio was approximately 2.17. Finally, the calculation of size independent fracture energies achieved using the modified WFM and BEM illustrated that they were quite similar.