Evolution of the fracture process zone in high-strength concrete under different loading rates

Compared with the extensive research on properties of the fracture process zone (FPZ) under quasi-static loading conditions, much less information is available on its dynamic characterization, especially for high-strength concrete (HSC). This paper presents the very recent results of an experimental program aimed at disclosing the loading rate effect on the size and velocity of the (FPZ) in HSC. Eighteen three-point bending specimens were conducted under a wide range of loading rates from from 10-4 mm/s to 103 mm/s using either a servo-hydraulic machine or a self-designed drop-weight impact device. Four strain gauges mounted along the ligament of the specimen were used to measure the FPZ size. Surprisingly, the FPZ size remains almost constant (around 20 mm) when the loading rate varies seven orders of magnitude.

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Eight Types of HSC

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.147.293 ◽

2011 ◽

Vol 147 ◽

pp. 293-297

Author(s):

Rena C. Yu ◽

Luis Saucedo ◽

Gonzalo Ruiz ◽

Xiao Xin Zhang

Keyword(s):

High Strength Concrete ◽

Fracture Process ◽

Fracture Process Zone ◽

Process Zone ◽

High Strength ◽

Fracture Properties ◽

Strength Concrete ◽

Mechanical And Fracture Properties

In this paper we report the composition, mechanical and fracture properties of eight types of performance-designed high strength concrete. The influences of compositions on the material’s brittleness are explained through the calculated reference size of the Fracture Process Zone (FPZ).

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Study on Interfacial Crack Propagation and Fracture between Embedded Steel and HSHPC

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.348-349.853 ◽

2007 ◽

Vol 348-349 ◽

pp. 853-856

Author(s):

Shan Suo Zheng ◽

Lei Li ◽

Guo Zhuan Deng ◽

Liang Zhang

Keyword(s):

Crack Propagation ◽

High Performance ◽

Fracture Process ◽

Fracture Process Zone ◽

High Performance Concrete ◽

Process Zone ◽

Interfacial Crack ◽

High Strength ◽

Interfacial Fracture ◽

Softening Process

Steel reinforced high strength and high performance concrete (SRHSHPC) specimens were experimented to study the mechanical behaviors between steel and concrete interface. In experiment, interfacial bond softening process was observed, which can be explained in terms of damage along the interface, leading to progressive reduction of shear transfer capability between steel and high strength and high performance concrete (HSHPC). In this paper, bond softening process along the interface is considered in the analysis of crack-induced debonding. Interfacial bond-slip mechanism between steel and HSHPC is studied in detail based on fracture mechanics. With the help of acoustic emissions technology, the crack propagation in the interlayer was observed, thus the interfacial crack propagation and fracture model is set up. Under the assumption that the interlayer is weak concrete compared with concrete matrix, the stress field as well as displacement field around the crack tip is deduced. The characteristics of interfacial fracture process are discussed and a model for interfacial fracture process zone is built up. With this model, the size of fracture process zone can be derived. At last, the influence of the fracture process zone on interfacial fracture toughness is determined using critical fracture toughness. All these may contribute to improvement of theory for SRHSHPC composite structure.

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Effect of Loading Rate on the Fracture Behaviour of High-Strength Concrete

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.24-25.179 ◽

2010 ◽

Vol 24-25 ◽

pp. 179-185 ◽

Cited By ~ 1

Author(s):

Gonzalo Ruiz ◽

X.X. Zhang ◽

R.C. Yu ◽

E. Poveda ◽

R. Porras ◽

...

Keyword(s):

Fracture Energy ◽

High Strength Concrete ◽

Loading Rate ◽

High Strength ◽

Displacement Rate ◽

Cohesive Law ◽

Viscous Term ◽

Strength Concrete ◽

Loading Rates ◽

Static Conditions

This research deals with the sensitivity of eight types of performance-designed high-strength concrete to the loading rate. Variations in the composition of the concrete produce the desired performance, for instance having null shrinkage or being able to be pumped at elevated heights without segregation, but they also produce variations in the fracture properties that are reported in this paper. We performed tests at five loading rates spanning six orders of magnitude in the displacement rate, from 1.74  10-5 mm/s to 17.4 mm/s. Load-displacement curves show that their peak is higher as the displacement rate increases, whereas the corresponding displacement is almost constant. Fracture energy also increases, but only for loading rates higher than 0.01 mm/s. We use a formula based on a cohesive law with a viscous term to study the results. The correlation of the formula to the experimental results is good and it allows us to obtain the theoretical value for the fracture energy under strictly static conditions. In addition, both the fracture energy and the characteristic length of the concretes used in the study diminish as the compressive strength of their aggregates increases.

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Experimental Analysis of Fracture in High Strength Cementitious Composites

MRS Proceedings ◽

10.1557/proc-42-101 ◽

1984 ◽

Vol 42 ◽

Author(s):

Farhad Ansari

Keyword(s):

Fracture Process ◽

Fracture Process Zone ◽

Process Zone ◽

High Strength ◽

Plain Concrete ◽

Laser Speckle ◽

Cementitious Composites ◽

Special Technique ◽

Technical Literature ◽

Speckle Metrology

AbstractCharacterization of cementitious composites by their fracture properties has been difficult due to controversial results reported in the technical literature. Existing studies on the fracture behavior of plain concrete reveal some fracture characteristics that differ from those normally observed in metallic materials. Among these characteristics is the existence of a micro-cracking zone or process zone at the tip of an advancing crack. The determination of the fracture process zone in concrete is a difficult experimental problem, because the resulting deformation is strongly localized.In the present study, in-plane displacements in front of notched high strength concrete have been monitored. Laser speckle metrology, which is a special technique utilizing the speckle patterns of laser light for measurement of in-plane displacements, is employed. Experimental results indicate that a precise description of the fracture process zone is possible by speckle metrology.

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Empirical analysis of the fracture process in high strength concrete loaded in uniaxial compression

Fracture and Damage of Concrete and Rock - FDCR-2 ◽

10.1201/9781482271287-16 ◽

1993 ◽

pp. 138-150

Keyword(s):

Empirical Analysis ◽

Uniaxial Compression ◽

High Strength Concrete ◽

Fracture Process ◽

High Strength ◽

Strength Concrete

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Experimental Investigation of Concrete Transverse Deformations at Relatively High Loading Rates for Interpretation of High Strength Concrete Behavior

Applied Sciences ◽

10.3390/app11188460 ◽

2021 ◽

Vol 11 (18) ◽

pp. 8460

Author(s):

Iakov Iskhakov ◽

Ilya Frolov ◽

Yuri Ribakov

Keyword(s):

Theoretical Model ◽

High Strength Concrete ◽

Compressive Load ◽

High Strength ◽

High Loading ◽

Normal Strength Concrete ◽

Strength Concrete ◽

Loading Rates ◽

Loading Process ◽

Normal Strength

Loading rates affect the behavior of concrete specimens from the beginning of the loading process until failure. At rather high loading rates, longitudinal deformations in concrete specimens under a compressive load are practically elastic up until the ultimate limit state. It has been previously demonstrated that transverse deformations effectively indicate high-strength concrete behavior in the entire static loading process range. A theoretical model for cylindrical concrete specimen failure under compressive load, based on a structural phenomenon, has also been proposed. The aim of the present research is experimental verification of using transverse deformations in addition to longitudinal ones for investigating high-strength concrete behavior at the non-elastic stage. This research is based on testing normal-strength concrete cylindrical specimens under compression at relatively high loading rates. The theoretical model of the cracking and failure scheme of the cylindrical specimens are experimentally confirmed. The obtained results demonstrate that it is possible to use transverse deformations for the interpretation of initiation and development of inelastic deformations in high-strength concrete up to class C90 based on the data for normal-strength concrete specimens of class C30 subjected to relatively high loading rates.

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