Complex investigations of the development of micro- and macro-cracks in concrete members: experiments and discrete element method modelling
concrete, damage detection, micro-cracks, macro-cracks, discrete element, method, concrete meso-structure, micro-computed tomography, elastic wave propagation
Concrete is one of the most common materials in civil engineering. The problem with concrete structures, however, is that they tend to fracture and crack with use; the mechanical properties of concrete are degraded due to environmental and operational loads. Microcracks appear even before a macrocrack shows up in an element. Detecting such microdamage at an early stage of degradation is not a trivial task and plays a vital role in civil engineering.
The research project aims to enhance the safety of concrete structures, using the phenomenon of elastic wave propagation. The characteristics of waves that propagate in mechanically degraded concrete are considerably altered, which makes it possible to detect incipient damage. From a broader perspective, the findings of the project can be expected to significantly contribute to the development of new monitoring techniques. A reliable way to assess the degree of concrete degradation in various structural elements will allow their maintenance costs to be rationalized and extend their service life.
The aim of the project is to explain the mechanism of propagation and scattering of elastic waves at the aggregate-level and their interaction with micro- and macro-cracking in concrete members subjected to monotonic quasi-static loading. Research investigations consist of two complementary parts: experimental and numerical. In the experimental part, a comprehensive program of monitoring of micro- and macro-cracks’ development in concrete specimens will be carried out by means of elastic waves. Two approaches using elastic waves will be used, i.e. the ultrasonic testing, where the elastic wave is generated by a PZT actuator, and the acoustic emission testing, where the elastic wave is generated by cracking of concrete. Additionally, the advanced micro-computed tomography system will be used for imaging the 3D concrete meso-structure and fracture evolution in concrete.
Since concrete has a special structure that is discontinuous and heterogeneous, wave propagation mechanisms in concrete elements will be described using an advanced mathematical model based on the discrete element method. In the numerical part the 4-phase concrete model will be used by including aggregates, cement matrix, macro-pores and interfacial transitional zones around aggregates. Calculations of elastic wave propagation in concrete elements will be conducted taking into account their real meso-structure obtained by means of micro-computed tomography.
The coupled experiments and calculations will yield new insight into the propagation of elastic waves in heterogeneous materials. The influence of concrete meso-structure on elastic wave scattering will be studied. Relationships between the micro/macro-cracks and characteristics of propagating acoustic and ultrasonic waves at the aggregate level will be elaborated. New algorithms capable of detecting micro-defect zones before the formation of visible damage will be developed.
- Financial Program Name:
- Narodowe Centrum Nauki (NCN) (National Science Centre)
- UMO-2019/35/B/ST8/01905 z dnia 2020-09-01
- Realisation period:
- 2020-09-01 - 2023-08-31
- Project manager:
- prof. dr hab. inż. Magdalena Rucka
- Team members:
- researcher Magdalena Knak
- researcher dr inż. Monika Zielińska
- researcher dr hab. inż. Michał Nitka
- researcher dr inż. Erwin Wojtczak
- researcher dr hab. inż. Łukasz Skarżyński
- researcher prof. dr hab. inż. Jacek Tejchman
- Realised in:
- Katedra Wytrzymałości Materiałów
- Project's value:
- 1 194 000.00 PLN
- Request type:
- National Research Programmes
- Domestic project
- Verified by:
- No verification
Papers associated with that project
Internal imaging of concrete fracture based on elastic waves and ultrasound computed tomographyPublication
The condition assessment of concrete structures belongs to the greatest challenges of non-destructive testing. Monitoring the fracture process of concrete and detecting cracks at the earliest possible stage is a vital aspect to ensure the safety of civil engineering objects. The use of ultrasound tomography enables imaging the internal structure of a tested element. This study aims at the visualization of fracture damage in concrete...
Monitoring the fracture process of concrete during splitting using integrated ultrasonic coda wave interferometry, digital image correlation and X-ray micro-computed tomographyPublication
The paper deals with the continuous-time monitoring of mechanical degradation in concrete cubes under splitting. A series of experiments performed with integrated coda wave interferometry (CWI) and digital image correlation (DIC), supported with X-ray micro-computed tomography (micro-CT) is reported. DIC and micro-CT techniques were used to characterize the fracture process in detail. CWI method was proved to be effective in the...
The effect of external load on ultrasonic wave attenuation in steel bars under bending stressesPublication
The stress state in deformed solids has a significant impact on the attenuation of an ultrasonic wave propagating through the medium. Measuring a signal with certain attenuation characteristics can therefore provide useful diagnostic information about the stress state in the structure. In this work, basic principles behind a novel attenuation-based diagnostic framework are introduced. An experimental study on steel bars under three-point...
Characterization of fracture process in polyolefin fibre-reinforced concrete using ultrasonic waves and digital image correlationPublication
This study explores the monitoring of the fracture process in concrete beams and aims to characterize the evolution of damage in polyolefin fibre-reinforced concrete beams by utilizing the integrated application of two measurement techniques, digital image correlation and ultrasonic testing. The interpretation of registered wave time histories data was provided by the calculation of the magnitude-phase-composite metrics. An efficient...
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