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Tailoring the Mechanical Properties of High-Aspect-Ratio Carbon Nanotube Arrays using Amorphous Silicon Carbide Coatings

Poelma, R.H. (author), Morana, B. (author), Vollebregt, S. (author), Schlangen, H.E.J.G. (author), Van Zeijl, H.W. (author), Fan, X. (author), Zhang, G.Q. (author)

The porous nature of carbon nanotube (CNT) arrays allows for the unique opportunity to tailor their mechanical response by the infiltration and deposition of nanoscale conformal coatings. Here, we fabricate novel photo-lithographically defined CNT pillars that are conformally coated with amorphous silicon carbide (a-SiC) to strengthen the...

journal article 2014

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Microscale Testing and Modelling of Cement Paste as Basis for Multi-Scale Modelling

Zhang, H. (author), Šavija, B. (author), Chaves Figueiredo, S. (author), Lukovic, M. (author), Schlangen, E. (author)

This work aims to provide a method for numerically and experimentally investigating the fracture mechanism of cement paste at the microscale. For this purpose, a new procedure was proposed to prepare micro cement paste cubes (100 × 100 × 100 µm3) and beams with a square cross section of 400 × 400 µm2. By loading the cubes to failure with a...

journal article 2016

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Influence of microencapsulated phase change material (PCM) addition on (micro) mechanical properties of cement paste

Šavija, B. (author), Zhang, H. (author), Schlangen, E. (author)

Excessive cracking can be a serious durability problem for reinforced concrete structures. In recent years, addition of microencapsulated phase change materials (PCMs) to concrete has been proposed as a possible solution to crack formation related to temperature gradients. However, the addition of PCM microcapsules to cementitious materials...

journal article 2017

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Combined experimental and numerical study on micro-cube indentation splitting test of cement paste

Zhang, H. (author), Šavija, B. (author), Schlangen, E. (author)

The aim of this paper is to investigate the fracture performance of cement paste at micro scale by both experimental and numerical methods. Micro cubic specimens with length of 100 µm were fabricated by precision cutting, grinding and micro-dicing, and tested by splitting with a wedge tip mounted on a nano-indenter. A nominal splitting...

journal article 2018

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Size effect on splitting strength of hardened cement paste: Experimental and numerical study

Zhang, H. (author), Šavija, B. (author), Xu, Y. (author), Schlangen, E. (author)

Cement paste possesses complex microstructural features including defects/pores over a range of length-scales, from nanometres to millimetres in size. As a consequence, it exhibits different behaviour under loading depending on the size. In this work, cubic specimens in a size range of 1: 400 were produced and tested by a one-sided splitting...

journal article 2018

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Static and Fatigue Tests on Cementitious Cantilever Beams Using Nanoindenter

Gan, Y. (author), Zhang, H. (author), Šavija, B. (author), Schlangen, E. (author), van Breugel, K. (author)

Cement paste is the main binding component in concrete and thus its fundamental properties are of great significance for understanding the fracture behaviour as well as the ageing process of concrete. One major aim of this paper is to characterize the micromechanical properties of cement paste with the aid of a nanoindenter. Besides, this paper...

journal article 2018

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Towards understanding stochastic fracture performance of cement paste at micro length scale based on numerical simulation

Zhang, H. (author), Šavija, B. (author), Schlangen, E. (author)

This work presents a study of stochastic fracture properties of cement paste at the micro length scale based on a combination of X-ray computed tomography (XCT) technique and discrete lattice type fracture model. Thirty virtual specimens consisting of pore, outer hydration products, inner hydration products and anhydrous cement particles were...

journal article 2018

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Combined experimental and numerical study of uniaxial compression failure of hardened cement paste at micrometre length scale

Zhang, H. (author), Xu, Y. (author), Gan, Y. (author), Chang, Z. (author), Schlangen, E. (author), Šavija, B. (author)

The aim of this work is to investigate the mechanical performance of hardened cement paste (HCP) under compression at the micrometre length scale. In order to achieve this, both experimental and numerical approaches were applied. In the experimental part, micrometre sized HCP specimens were fabricated and subjected to uniaxial compression by...

journal article 2019

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Assessing Hydrated Cement Paste Properties Using Experimentally Informed Discrete Models

Šavija, B. (author), Zhang, H. (author), Schlangen, E. (author)

Properties of concrete are, to a large extent, dependent on the properties of its binding constituent, hydrated cement paste. Therefore, knowledge of properties of hydrated cement paste is crucial for predicting concrete behavior. This paper presents an experimentally informed approach for modeling elastic and transport properties of cement...

journal article 2019

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Experimentally informed fracture modelling of interfacial transition zone at micro-scale

Zhang, H. (author), Gan, Y. (author), Xu, Y. (author), Zhang, Shizhe (author), Schlangen, E. (author), Šavija, B. (author)

The aim of this work is to predict the micromechanical properties of interfacial transition zone (ITZ) by combining experimental and numerical approaches. In the experimental part, hardened cement paste (HCP) cantilevers (200 μm × 100 μm × 100 μm) attached to a quartzite aggregate were fabricated and tested using micro-dicing saw and...

journal article 2019

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Experimentally informed micromechanical modelling of cement paste: An approach coupling X-ray computed tomography and statistical nanoindentation

Zhang, H. (author), Šavija, B. (author), Lukovic, M. (author), Schlangen, E. (author)

This work proposes a method for numerically investigating the fracture mechanism of cement paste at the microscale based on X-ray computed tomography and nanoindentation. For this purpose, greyscale level based digital microstructure was generated by X-ray microcomputed tomography with a resolution of 2 μm/voxel length. In addition,...

journal article 2019

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Deformation and fracture of 3D printed disordered lattice materials: Experiments and modeling

Xu, Y. (author), Zhang, H. (author), Šavija, B. (author), Chaves Figueiredo, S. (author), Schlangen, E. (author)

A method is presented to model deformation and fracture behavior of 3D printed disordered lattice materials under uniaxial tensile load. A lattice model was used to predict crack pattern and load-displacement response of the printed lattice materials. To include the influence of typical layered structures of 3D printed materials in the...

journal article 2019

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Cementitious cellular composites with auxetic behavior

Xu, Y. (author), Zhang, H. (author), Schlangen, E. (author), Lukovic, M. (author), Šavija, B. (author)

Auxetic behavior refers to material with negative Poisson's ratio. In this research, a new type of cementitious auxetic material is developed. A novel crack bridging auxetic mechanism is discovered which is in contrast with a local buckling mechanism commonly employed to trigger auxetic behavior. Taking advantage of 3D printing techniques,...

journal article 2020

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Microstructure informed micromechanical modelling of hydrated cement paste: Techniques and challenges

Zhang, H. (author), Xu, Y. (author), Gan, Y. (author), Chang, Z. (author), Schlangen, E. (author), Šavija, B. (author)

Application of micromechanical modelling of hydrated cement paste (HCP) gains more and more interests in the field of cementitious materials. One of the most promising approaches is the use of so-called microstructure informed micromechanical models, which provides a direct link between microstructure and mechanical properties. In order to...

journal article 2020

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Experimentally validated meso-scale fracture modelling of mortar using output from micromechanical models

Zhang, H. (author), Xu, Y. (author), Gan, Y. (author), Schlangen, E. (author), Šavija, B. (author)

This paper presents a validation process of the developed multi-scale modelling scheme on mortar composites. Special attention was paid to make the material structure of real and virtual mortar specimens comparable at the meso-scale. The input mechanical parameters of cement paste (both bulk cement paste and interfacial transition zone) at the...

journal article 2020

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Lattice Fracture Model for Concrete Fracture Revisited: Calibration and Validation

Chang, Z. (author), Zhang, Hongzhi (author), Schlangen, E. (author), Šavija, B. (author)

The lattice fracture model is a discrete model that can simulate the fracture process of cementitious materials. In this work, the Delft lattice fracture model is reviewed and utilized for fracture analysis. First, a systematic calibration procedure that relies on the combination of two uniaxial tensile tests is proposed to determine the input...

journal article 2020

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Effect of printing parameters on interlayer bond strength of 3D printed limestone-calcined clay-based cementitious materials: An experimental and numerical study

Chen, Y. (author), Jansen, K. (author), Zhang, H. (author), Romero Rodriguez, C. (author), Gan, Y. (author), Copuroglu, Oguzhan (author), Schlangen, E. (author)

For a single batch material, time intervals and nozzle standoff distances between two subsequent layers are two critical printing parameters that influence the mechanical performance of the printed concrete. This paper presents an experimental and numerical study to investigate the impacts of these printing parameters on the interlayer bond...

journal article 2020

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Discrete lattice fracture modelling of hydrated cement paste under uniaxial compression at micro-scale

Jiang, Nengdong (author), Zhang, Hongzhi (author), Chang, Z. (author), Schlangen, E. (author), Ge, Zhi (author), Šavija, B. (author)

A combination of laboratory experiments and numerical simulations at multiple length scales can provide in-depth understanding of fracture behaviour of hydrated cement paste (HCP). To that end, the current work presents a numerical study on compressive failure of hydrated cement paste (HCP) at the micro-scale. Virtual specimens consisting of...

journal article 2020

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Elucidating the effect of accelerated carbonation on porosity and mechanical properties of hydrated Portland cement paste using X-ray tomography and advanced micromechanical testing

Zhang, H. (author), Romero Rodriguez, C. (author), Dong, H. (author), Gan, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Carbonation of hydrated cement paste (HCP) causes numerous chemo-mechanical changes in the microstructure, e.g., porosity, strength, elastic modulus, and permeability, which have a significant influence on the durability of concrete structures. Due to its complexity, much is still not understood about the process of carbonation of HCP. The...

journal article 2020

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Micro-cantilever testing on the short-term creep behaviour of cement paste at micro-scale

Gan, Y. (author), Vandamme, Matthieu (author), Zhang, Hongzhi (author), Chen, Y. (author), Schlangen, E. (author), van Breugel, K. (author), Šavija, B. (author)

This study proposes an experimental method for studying the short-term creep behaviour of cement paste at micro-scale. The micro-bending tests on miniaturized cantilever beams were used to characterize the viscoelastic properties of cement paste. The effects of w/b ratio, the type of binder and the stress level on the microscopic creep...

journal article 2020