Mechanical and Self-Healing Performances of Crumb Rubber Modified High-Strength Engineered Cementitious Composites

Yu Jiangtao,Li Mi,Jiang Fangming,Yang Qi,Xing Qiong

doi:10.3389/fmats.2021.811110

Abstract

High-strength engineered cementitious composite (HS-ECC) reinforced with polyethylene (PE) fiber characterizes wider crack widths than the conventional polyvinyl alcohol fiber-reinforced ECC (PVA-ECC), weakening the self-healing potential of HS-ECC. The properties of HS-ECC are tailored by introducing crumb rubber (CR), as artificial flaws can lower the matrix toughness and the crack width, leading to an enhanced self-healing potential of HS-ECC. In this study, CR is used to entirely replace silica sand (SS) with three equivalent aggregate-to-binder ratios of 0.2, 0.4, and 0.6, and two CR particle sizes (i.e., CR1 and CR2) are also considered to investigate the effects on density, compressive properties, and tensile performances of HS-ECC. Although CR substitution of SS influences adversely the mechanical strengths of HS-ECC, it can reduce the HS-ECC matrix fracture toughness, activate more microcracks, and reduce the crack width. Moreover, CR-modified HS-ECC specimens featuring the smallest crack width were preloaded to three specific strain levels, including 0.5%, 1.0%, and 2.0%, and then experienced wet–dry conditioning to exhibit effective mechanical and non-mechanical property recovery. The further hydration of binder materials enhances the interfacial bond stress and thus retains the mechanical performances of self-healed HS-ECC, which is expected to improve the practical application and benefit the sustainability of HS-ECC.

Highlights

Concrete, as the most extensively used building material in the world featuring intrinsic brittleness, is prone to cracking during its service life, which negatively impacts its mechanical performance and leads to potential safety risks to infrastructure
The loss of the compressive strength of High-strength engineered cementitious composite (HS-Engineered cementitious composite (ECC)) with crumb rubber (CR) substitution can be attributed to the lower stiffness of CR particle compared with silica sand (SS), the increment of closed pores within the matrix caused by CR addition (Oikonomou and Mavridou, 2009), and the weak interfacial bond between the CR and around the cementitious matrix
Comparing the compressive strength of CR1-0.4 and CR2-0.4 in Figure 3, it is evident that the negative impact on the compressive strength due to CR substitution can be diminished to a certain degree by using CR with a smaller particle size (i.e., CR2-0.4)

Summary

Introduction

As the most extensively used building material in the world featuring intrinsic brittleness, is prone to cracking during its service life, which negatively impacts its mechanical performance and leads to potential safety risks to infrastructure. Self-Healing ECC immersion and cyclic wet–dry exposures) (Jacobsen et al, 1996; Edvardsen, 1999), and small crack widths (Jacobsen et al, 1996; Reinhardt and Jooss, 2003). The tensile strength of PVA-ECC falls in the range of 3–6 MPa with a compressive strength of less than 60 MPa (Reinhardt and Jooss, 2003; Yu et al, 2017), which are lower and may hinder its application in practical engineering

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