Influence of type of aggregate and surface roughness on the interface fracture properties

Abstract

An experimental investigation of interface fracture in high strength concrete is reported. An attempt has been made to study the influence of strength of mortar, type of aggregate and its roughness on interface fracture properties. The parameters include load-CMOD variations, tensile strength, and fracture energy of the interface. Stiffness, compliance and ductility factors of the composite specimens have been evaluated in Mode-I loading. The fracture energy increases as the roughness of the aggregate surface increases. The stiffness of the composite specimen increases as the roughness of the aggregate surface increases. The ductility factor (i.e. the fracture energy per unit of peak load) decreases as the surface area of the interface increases in sandwiched composite specimens in Mode-I failure, whereas it increases with the interface area in composite specimens with mortar cast against rough concrete aggregates. The interface exhibits brittle behavior with catastrophic failure indicating the application of LEFM to the interface.

Multi-scale Review for Possible Mechanisms of Natural Frequency Change of Reinforced Concrete Structures under an Ordinary Drying Condition

“…As the porosity in the ITZ is more than three times that of normal mortar located far from the surface of the aggregate (Scrivener and Gartner 1988;Scrivener et al 2004), resistivity to shrinkage of mortar matrix is low. Therefore, even there is a report that the thickness of ITZ depends on the size of aggregates (Xie et al 1991;Ollivier et al 1995;Tasong et al 1999;Rao and Raghu Prasad 2004), the resistivity of aggregate to the shrinkage of mortar matrix can be evaluated by the ratio of thickness of ITZ to the radius of aggregate. The larger size of aggregate has a large restraint role to the mortar shrinkage, while the smaller size of aggregate has a small restraint role.…”

A stochastic multiscale peridynamic model for corrosion-induced fracture in reinforced concrete

“…In terms of the interfacial fracture property, we take into account that in concrete, the interface between aggregates and matrix is generally weaker than both of them. The fracture energy of the interface in concrete materials is found in experiments to be 4% -34% that of the mortar, with a value estimated to be between 2.5 -25.3 N/m [79]. Surface roughness also affects the fracture energy, increasing fracture energy with increasing roughness [79].…”

Mesoscale modelling of concrete tensile failure mechanism at high strain rates

“…Its formation is due to the water filled pores near the aggregate and the wall effect [6]. According to static experimental and numerical results, it is well known that ITZ plays a very important role in a concrete mix and it is considered to be the weak link in a concrete composite with respect to its mechanical performance.…”

“…Many research works have been done to study the properties of ITZ and its effect on the static mechanical properties of concrete material [6][7][8][9][10][11][12][13][14]. The research methods can be broadly categorized as three types, i.e., experimental approach, analytical method and numerical simulation.…”

“…Most of the works are based on experimental results. In Appa Rao and Raghu Prasad's work [6], double-edge notched composite compact tension specimens were adopted to measure the fracture energy of the interface, then the influence of strength of mortar, type of aggregate and its roughness on ITZ fracture properties were analyzed. It had been proven that the tensile strength of the ITZ is much lower than the strength of the mortar matrix.…”