Flexural fracture response of a novel iron carbonate matrix – Glass fiber composite and its comparison to Portland cement-based composites

Abstract

h i g h l i g h t sFracture response of a novel iron-based binder system brought out. Significantly higher fracture properties as compared to OPC systems. Superior influence of the unreacted metallic particles in the system elucidated. Digital image correlation method used for fracture property determination. a b s t r a c tThis paper explores the fracture properties of a novel and sustainable glass-fiber reinforced composite, the matrix for which is formed through the aqueous, anoxic, room-temperature carbonation of (waste) metallic iron powder along with other minor ingredients. A comparison of the properties of this binder with Ordinary Portland Cement pastes, which constitutes one of the most common and economic ceramic matrices is also provided. The iron-based binder system exhibits fracture parameters (fracture toughness, K IC S and critical crack tip opening displacement, CTOD C , determined using two parameter fracture model, TPFM) that are significantly higher when compared to those of the OPC systems in both the unreinforced and glass fiber reinforced states. The beneficial influence of the unreacted metallic iron particles of large aspect ratio, on the fracture parameters of iron-based binders are elucidated. The strain energy release rates show trends that are in line with the fracture parameters from TPFM. The elastic and inelastic components of strain energy release rate are separated in an effort to capture the fundamental toughening mechanisms in these systems. The fracture parameters determined using a non-contact, digital image correlation technique are found to relate well to those obtained from TPFM.

Elucidating the Crack Resistance of Alkali‐Activated Slag Mortars Using Coupled Fracture Tests and Image Correlation

“…The elastic component is the result of resistance to incremental crack growth, and thus can be related to the elastic properties of the material. 25,30 The lower the elastic component, the lesser is the resistance to the growth of the driving crack. The inelastic component relates to effects such as permanent deformation resulting from crack opening.…”

Experimental and Numerical Investigation of Fracture Behavior of Particle-Reinforced Alkali-Activated Slag Mortars

“…Fundamental characterization of fracture response in quasi-brittle materials also requires direct observation of fracture process zone (FPZ) which is denoted by the zone of strain localization near the tip of the advancing crack. FPZ has been geometrically quantified using microscopy (Hadjab.S et al 2007;Nemati 2006), photography (Bhargava and Rehnström 1975) or a non-contact speckle-tracking method called digital image correlation(DIC) (Das et al 2014a(Das et al , 2015bSkarżyński et al 2013;Yates et al 2010). In DIC, the surface displacements and strain maps are obtained by correlating the images and the direct measurements of the crack extensions/FPZ are quantified from the displacement/strain maps.…”

Temperature-induced phase and microstructural transformations in a synthesized iron carbonate (siderite) complex

“…The sensitivity of these parameters to the carbonation efficiency and compressive strength resulted in the selection of appropriate material designs [16]. Further studies on the pore structure, microstructure [22] and mechanical response [23] were carried out to explain the enhanced performance characteristics of this material and establish it as a viable and sustainable alternative to OPC-based systems. A strong carbonate matrix and microstructural reinforcement through particulate inclusions resulted in beneficial mechanical properties.…”

“…While the aforementioned studies [16,23] established the superior mechanical performance of iron carbonate binder as compared to OPC binders at normal operating temperatures, it is important to evaluate the response of this material to elevated temperatures from the viewpoint of its chemistry and microstructure. This helps in: (i) enabling design of resilient iron carbonate-based building envelope and structural components that can better tolerate fire hazards (especially when the temperature rises to 600 o C or more as is shown in this paper), and (ii) developing high-temperature resistant, ceramic-like matrices processed at high temperatures for applications in refractory linings, solar power concentrators, and airfield pavement surfaces for military aircrafts (not an exhaustive list).…”

“…It is also well known that hardened OPC paste loses its integrity and structural capacity at elevated temperatures [24][25][26]. Since the reaction product in the iron carbonate binder is chemically different, and there is a large amount of unreacted iron particles [22,23] that are capable of reinforcing the matrix, the high temperature response is expected to be significantly different from that of OPC-based matrices. This paper comprehensively investigates the temperature-induced chemical and microstructural transformations in this material through several advanced characterization techniques.…”