Role of porosity in controlling the mechanical and impact behaviours of cement-based materials

Abstract

This work deals with the influence of porosity on the tensile, the compressive and the impact behaviours of two fine cementitious mortars one with silica fume and one without. The addition of silica fume is shown to change the pore size distribution. The mix without silica fume is characterized by porosity at the scale of the grains of fine sand (approximately 100 mm), while silica fume addition results in a more porous matrix with pore sizes of millimetre length size. The mortar with silica fume shows a higher quasi static compressive and flexural strength whereas the mix without silica fume is observed to be less compressible (by irreversible reduction of volume) under heavy confinement pressure (quasi oedometric tests) and shows better ballistic performance. A numerical simulation of the impact tests employing the Krieg, Swenson and Taylor model, which accounts for both deviatoric and volumetric inelastic behaviour of the material, was undertaken using the data from quasi oedometric tests. These calculations follow the experimental results and confirm the influence of the macroscopic porosity on the impact performance of cement based materials.

An experimental method of measuring the quasi-static and dynamic confined behaviour of PMMA

“…Burlion et al [11], for instance, developed an instrumented elastic steel vessel. Forquin et al [12][13][14] proposed a new analysis of experimental data taking account of the shortening of specimen and of a possible plastic deformation of the confining cell. More recently, dynamic QOC tests have been performed with a split-Hopkinson pressure bar device in the range of strain-rates from 80 to 200/s applying the previous methodology [15][16].…”

Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size

“…. ), regarding accidental or intentional hazards such as ballistic impact, blasting, rock fall, plane crash or also earthquake, concrete can be exposed to extreme loading involving high hydrostatic pressure up to 1 GPa and high strainrate levels (several hundreds of 1/s) [1]. Under such loading conditions shear mechanisms and collapse of pores are observed.…”

Relationship Between Mesostructure, Mechanical Behaviour and Damage of Cement Composites Under High-Pressure Confinement

“…In the 1980s, the appearance of high-or very-highperformance concretes with average failure stress under simple compression of 60-120 MPa [1], and then the emergence of ultra-high-performance concretes of over 200 MPa in the 1990s [2], have stimulated studies concerning the mechanical behaviour of these materials and their applications [3][4][5]. In particular, because of their easy use and high hardness, these types of materials are attractive as structural and impact-resistant materials [6,7].…”

“…In a concrete structure subjected to shock or impact, severe hydrostatic compression is found near the impact location and a field of confined compression is created ahead of the projectile, which produces irreversible reduction of the volume [5,11,12]. The resistance of the material under high pressure, the law of compaction (evolution of volumetric strain) and the elastic parameters, condition the penetration of the projectile into the target [10,13,14].…”

“…The resistance of the material under high pressure, the law of compaction (evolution of volumetric strain) and the elastic parameters, condition the penetration of the projectile into the target [10,13,14]. The analysis of the concrete subjected to this type of impact loading implies knowing the effect that high-pressure confinement exerts on the mechanical properties [5,[10][11][12].…”