Complex investigations of the development of micro- and macro-cracks in concrete members: experiments and discrete element method modelling - Project - Bridge of Knowledge

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Complex investigations of the development of micro- and macro-cracks in concrete members: experiments and discrete element method modelling

The scientific goal of the project is to explain the mechanism of propagation of elastic waves at the meso-level and their interaction with micro- and macro-cracking in concrete members subjected to monotonic quasi-static loading. This mechanism will be described by means of the advanced mathematical model based on the extended discrete element method (DEM). Because concrete has a particular structure that is discontinuous and heterogeneous, DEM is a suitable tool for investigating its mechanical behaviour at the aggregate level (meso-level). The DEM approach will allow for a precise reconstruction of the meso-structure of concrete and analyses of the evolution of micro- and macro-cracks and propagation of elastic waves at the level of aggregates during concrete deformation. The measurable effect of the project implementation will be papers published in journals indexed on the JCR list.

Keywords:

concrete, damage detection, micro-cracks, macro-cracks, discrete element, method, concrete meso-structure, micro-computed tomography, elastic wave propagation

Illustration of the publication
Illustration of the publication

Project description:

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.

Details

Financial Program Name:
OPUS
Organization:
Narodowe Centrum Nauki (NCN) (National Science Centre)
Agreement:
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:
Realised in:
Katedra Wytrzymałości Materiałów
Project's value:
1 194 000.00 PLN
Request type:
National Research Programmes
Domestic:
Domestic project
Verified by:
No verification

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