Application of depth-sensing microindentation testing to study of interfacial transition zone in reinforced concrete

Zhu, Wenzhong; Bartoš, Petr

doi:10.1016/s0008-8846(00)00322-7

Cited by 80 publications

(22 citation statements)

References 6 publications

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“…It was shown that the modern DSNI techniques allow the researchers to study the mechanical properties of various micro/nanoscale features of distinct constituents of various cementitious materials including synthetically prepared pure cement clinker phases and selected hydrate phases in well-hydrated cement pastes (see, e.g. [16,17,27,40,43,45,46] and references therein). There are a few recently published works that utilize the depth-sensing nanoindentation for inhomogeneous materials such as rocks [2,47].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of elastic modulus and hardness of highly inhomogeneous materials by nanoindentation

2015

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The experimental and numerical techniques for evaluation of mechanical properties of highly inhomogeneous materials are discussed. The techniques are applied to coal as an example of such a material. Characterization of coals is a very difficult task because they are composed of a number of distinct organic entities called macerals and some amount of inorganic substances along with internal pores and cracks. It is argued that to avoid the influence of the pores and cracks, the samples of the materials have to be prepared as very thin and very smooth sections, and the depth-sensing nanoindentation (DSNI) techniques has to be employed rather than the conventional microindentation. It is shown that the use of the modern nanoindentation techniques integrated with transmitted light microscopy is very effective for evaluation of elastic modulus and hardness of coal macerals. However, because the thin sections are glued to the substrate and the glue thickness is approximately equal to the thickness of the section, the conventional DSNI techniques show the effective properties of the section/substrate system rather than the properties of the material. As the first approximation, it is proposed to describe the sample/substrate system using the classic exponential weight function for the dependence of the equivalent elastic contact modulus on the depth of indentation. This simple approach allows us to extract the contact modulus of the material constitutes from the data measured on a region occupied by a specific component of the material. The proposed approach is demonstrated on application to the experimental data obtained by Berkovich nanoindentation with varying maximum depth of indentation.

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Section: Introductionmentioning

confidence: 99%

Evaluation of elastic modulus and hardness of highly inhomogeneous materials by nanoindentation

2015

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“…This factor is assumed to have a value between 0.2 and 0.8, although there is not enough theoretical or experimental evidence to support this assumption [5]. In some recent studies, attempts were made to determine the local mechanical properties of the ITZ using microindentation or microhardness testing [7][8][9]. Asbridge et al reported about 20 percent reduction in Knoop microhardness in the ITZ than the bulk matrix at w/c of 0.4 and 0.5 [9], however similar Knoop microhardness at w/c 0.6.…”

Section: Introductionmentioning

confidence: 99%

Nanomechanical Properties of Interfacial Transition Zone in Concrete

Mondal

Shah

Marks

2009

Nanotechnology in Construction 3

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Abstract. This research provides better understanding of the nanostructure and the nanoscale local mechanical properties of the interfacial transition zone (ITZ) in concrete. Nanoindentation with in-situ scanning probe microscopy imaging was used to compare the properties of the bulk paste with the properties of the ITZ between paste and two different types of aggregates. ITZ was found to be extremely heterogeneous with some areas as strong as the bulk matrix. Higher concentration of large voids and cracks along the interface was observed due to poor bonding. Nanoindentation results on relatively intact areas of the interface disagreed with the notion of increasing elastic modulus with distance from the interface. Depending on the aggregate type, average modulus of the ITZ was 70% to 85% of the average modulus of the paste matrix. The main problem the ITZ poses on the overall mechanical properties of concrete was concluded to be due to extreme heterogeneity within the interface and poor bonding between aggregate and paste. It was noted that the connectivity of the weaker areas such as large voids and cracks along the interface governs failure.

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“…A drastic drop in elastic modulus from 200 GPa in steel to 5.5-31.9 GPa in paste was observed along with high porosity and presence of weak phases in the ITZ [20]. Smallscale testing of the ITZ identified low mechanical properties of the Ca(OH) 2 -rich interfacial transition [34] and numerous large porosities [12], [20]. A sudden transition accompanied by an immediate change in properties between the steel and paste is recommended for lowering the bond strength between steel and cement [20].…”

Section: Adherence Testingmentioning

confidence: 98%

“…Micrometer scale characterizations were performed by depth-sensing micro-and nanoindentations [12], [20], [34]. The interfacial transition zone (ITZ) exhibits a large variability in mechanical behavior due to the heterogeneous components present: steel, hydrated phases, and unhydrated cement [20].…”

Section: Adherence Testingmentioning

confidence: 99%

Quantitative and representative adherence assessment of coated and uncoated concrete-formwork

Spitz

Coniglio

Mansori

et al. 2018

Surface and Coatings Technology

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Application of depth-sensing microindentation testing to study of interfacial transition zone in reinforced concrete

Cited by 80 publications

References 6 publications

Evaluation of elastic modulus and hardness of highly inhomogeneous materials by nanoindentation

Evaluation of elastic modulus and hardness of highly inhomogeneous materials by nanoindentation

Nanomechanical Properties of Interfacial Transition Zone in Concrete

Quantitative and representative adherence assessment of coated and uncoated concrete-formwork

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