TY - JOUR

T1 - Fatigue-Induced Damage in High-Strength Concrete Microstructure

AU - Oneschkow, Nadja

AU - Scheiden, Tim

AU - Hüpgen, Markus

AU - Rozanski, Corinna

AU - Haist, Michael

N1 - Funding Information: Funding: This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the collaborative project “Material composition influenced damage development in high-strength concrete under cyclic loading”, project number 353530889, within the DFG priority programme 2020 “Cyclic Deterioration of High-Performance Concrete in an Experimental-Virtual Lab”. The publication of this article was funded by the Open Access Fund of Leibniz Universität, Hannover.

PY - 2021/9/28

Y1 - 2021/9/28

N2 - A high-strength concrete subjected to compressive fatigue loading with two maximum stress levels was investigated and the behaviour was evaluated using the macroscopic damage indicators, strain and acoustic emission hits (AE-hits), combined with microstructural analyses utilising light microscopy and scanning electron microscopy (SEM). A clustering technique using Gaussian mixture modelling combined with a posterior probability of 0.80 was firstly applied to the AE-hits caused by compressive fatigue loading, leading to two clusters depending on the maximum stress level. Only a few cracks were visible in the microstructure using light microscopy and SEM, even in phase III of the strain development, which is shortly before failure. However, bluish impregnated areas in the mortar matrix of higher porosity or defects, changing due to the fatigue loading, were analysed. Indications were found that the fatigue damage process is continuously ongoing on a micro-or sub-microscale throughout the mortar matrix, which is difficult to observe on a mesoscale by imaging. Furthermore, the results indicate that two different damage mechanisms take place, which are pronounced depending on the maximum stress level. This might be due to diffuse and widespread compressive damage and localised tensile damage, as the findings documented in the literature suggest.

AB - A high-strength concrete subjected to compressive fatigue loading with two maximum stress levels was investigated and the behaviour was evaluated using the macroscopic damage indicators, strain and acoustic emission hits (AE-hits), combined with microstructural analyses utilising light microscopy and scanning electron microscopy (SEM). A clustering technique using Gaussian mixture modelling combined with a posterior probability of 0.80 was firstly applied to the AE-hits caused by compressive fatigue loading, leading to two clusters depending on the maximum stress level. Only a few cracks were visible in the microstructure using light microscopy and SEM, even in phase III of the strain development, which is shortly before failure. However, bluish impregnated areas in the mortar matrix of higher porosity or defects, changing due to the fatigue loading, were analysed. Indications were found that the fatigue damage process is continuously ongoing on a micro-or sub-microscale throughout the mortar matrix, which is difficult to observe on a mesoscale by imaging. Furthermore, the results indicate that two different damage mechanisms take place, which are pronounced depending on the maximum stress level. This might be due to diffuse and widespread compressive damage and localised tensile damage, as the findings documented in the literature suggest.

KW - Acoustic emission

KW - Compressive cyclic loading

KW - Damage mechanism

KW - High-strength concrete

KW - Light microscopy

KW - SEM

KW - Strain development

UR - http://www.scopus.com/inward/record.url?scp=85115992900&partnerID=8YFLogxK

U2 - 10.3390/ma14195650

DO - 10.3390/ma14195650

M3 - Article

VL - 14

JO - MATERIALS

JF - MATERIALS

SN - 1996-1944

IS - 19

M1 - 5650

ER -