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Effects of temperature on autogenous deformation and early-age stress evolution in cement pastes with low water to cement ratio

Liang, M. (author), Liu, C. (author), Liang, X. (author), Chang, Z. (author), Schlangen, E. (author), Šavija, B. (author)

This paper investigates the influence of temperature on autogenous deformation and early-age stress (EAS) evolution in ordinary Portland cement paste using a recently developed Mini Temperature Stress Testing Machine (Mini-TSTM) and Mini Autogenous Deformation Testing Machine (Mini-ADTM). In the Mini-TSTM/ ADTM, CEM I 42.5 N paste with a...

journal article 2023

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ASR: Insights into the cracking process via lattice fracture simulation at mesoscale based on the chemical reactions at microscale

Qiu, Xiujiao (author), Chang, Z. (author), Chen, J. (author), Schlangen, E. (author), Ye, G. (author), Schutter, Geert De (author)

In our former paper, based on a published 3D reactive transport model at microscale with the capability of simulating the chemical reactions involved in ASR, the location of expansive ASR gel related to the reactivity of aggregate, temperature, aggregate porosity and silica content in aggregate, is clarified. Based on the simulation results,...

journal article 2023

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Ultra-thin Strain Hardening Cementitious Composite (SHCC) layer in reinforced concrete cover zone for crack width control

He, S. (author), Mustafa, S. (author), Chang, Z. (author), Liang, M. (author), Schlangen, E. (author), Lukovic, M. (author)

In the current study, experiments and numerical simulations were carried out to investigate the cracking behavior of reinforced concrete beams consisting of a very thin layer (i.e., 1 cm in thickness) of SHCC in the concrete cover, tension zone. A novel type of SHCC/concrete interface that features a weakened chemical adhesion but an enhanced...

journal article 2023

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A review of methods on buildability quantification of extrusion-based 3D concrete printing: From analytical modelling to numerical simulation

Chang, Z. (author), Chen, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Herein, different kinds of methods for buildability quantification of 3D concrete printing are reviewed, including experimental approaches, analytical modelling, and numerical simulations. A brief introduction on printing process is first given. This discusses the material properties in different stages. Material printability, which...

journal article 2023

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An enhanced lattice beam element model for the numerical simulation of rate-dependent self-healing in cementitious materials

Sayadi, Sina (author), Chang, Z. (author), He, S. (author), Schlangen, E. (author), Mihai, I.C. (author), Jefferson, Anthony (author)

This paper describes the development of a discrete lattice model for simulating structures formed from self-healing cementitious materials. In particular, a new approach is presented for simulating time dependent mechanical healing in lattice elements. The proposed formulation is designed to simulate the transient damage and healing behaviour...

journal article 2023

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Predicting micromechanical properties of cement paste from backscattered electron (BSE) images by computer vision

Liang, M. (author), He, S. (author), Gan, Yidong (author), Zhang, Hongzhi (author), Chang, Z. (author), Schlangen, E. (author), Šavija, B. (author)

This paper employs computer vision techniques to predict the micromechanical properties (i.e., elastic modulus and hardness) of cement paste based on an input of Backscattered Electron (BSE) images. A dataset comprising 40,000 nanoindentation tests and 40,000 BSE micrographs was built by express nanoindentation test and Scanning Electron...

journal article 2023

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Lattice modelling of early-age creep of 3D printed segments with the consideration of stress history

Chang, Z. (author), Liang, M. (author), He, S. (author), Schlangen, E. (author), Šavija, B. (author)

We propose a new numerical method to analyze the early-age creep of 3D printed segments with the consideration of stress history. The integral creep strain evaluation formula is first expressed in a summation form using superposition principle. The experimentally derived creep compliance surface is then employed to calculate the creep strain...

journal article 2023

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Does early age creep influence buildability of 3D printed concrete? Insights from numerical simulations

Chang, Z. (author), Liang, M. (author), Chen, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Cementitious materials may exhibit significant creep at very early age. This is potentially important for concrete 3D printing, where the material is progressively loaded even before it sets. However, does creep actually affect the buildability of 3D printed concrete? Herein, the influence of early-age creep on the buildability of 3D printed...

journal article 2023

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Autogenous deformation induced- stress evolution in high-volume GGBFS concrete: Macro-scale behavior and micro-scale origin

Liang, M. (author), Chang, Z. (author), Zhang, Y. (author), Cheng, H. (author), He, S. (author), Schlangen, E. (author), Šavija, B. (author)

This study aims to experimentally investigate the autogenous deformation and the stress evolution in restrained high-volume ground granulated blast furnace slag (GGBFS) concrete. The Temperature Stress Testing Machine (TSTM) and Autogenous Deformation Testing Machine (ADTM) were used to study the macro-scale autogenous deformation and stress...

journal article 2023

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Early-age creep of 3D printable mortar: Experiments and analytical modelling

Chang, Z. (author), Liang, M. (author), Xu, Y. (author), Wan, Z. (author), Schlangen, E. (author), Šavija, B. (author)

In this study, an experimental setup to characterize the early-age creep of 3D printable mortar was proposed. The testing protocol comprises quasi-static compressive loading-unloading cycles, with 180-s holding periods in between. An analytical model based on a double power law was used to predict creep compliance with hardening time and...

journal article 2023

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Effect of curing methods during a long time gap between two printing sessions on the interlayer bonding of 3D printed cementitious materials

Chen, Y. (author), Chang, Z. (author), He, S. (author), Copuroglu, Oguzhan (author), Šavija, B. (author), Schlangen, E. (author)

A good bond between the layers of 3D printed cementitious materials is a prerequisite for having high structural rigidity for the printed elements. However, the influence of printing process on an interlayer bond is still not well understood. This study investigates the influence of curing methods (i.e., air curing, plastic film covering, wet...

journal article 2022

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Convolutional neural network for predicting crack pattern and stress-crack width curve of air-void structure in 3D printed concrete

Chang, Z. (author), Wan, Z. (author), Xu, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Extrusion-based 3D concrete printing (3DCP) results in deposited materials with complex microstructures that have high porosity and distinct anisotropy. Due to the material heterogeneity and rapid growth of cracks, fracture analysis in these air-void structures is often complex, resulting in a high computational cost. This study proposes a...

journal article 2022

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Microstructure-informed deep convolutional neural network for predicting short-term creep modulus of cement paste

Liang, M. (author), Gan, Y. (author), Chang, Z. (author), Wan, Z. (author), Schlangen, E. (author), Šavija, B. (author)

This study aims to provide an efficient alternative for predicting creep modulus of cement paste based on Deep Convolutional Neural Network (DCNN). First, a microscale lattice model for short-term creep is adopted to build a database that contains 18,920 samples. Then, 3 DCNNs with different consecutive convolutional layers are built to learn...

journal article 2022

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Stress evolution in restrained GGBFS concrete due to autogenous deformation: bayesian optimization of aging creep

Liang, M. (author), Li, Z. (author), He, S. (author), Chang, Z. (author), Gan, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Stress evolution of restrained concrete is a significant direct index in early-age cracking (EAC) analysis of concrete. This study presents experiments and numerical modelling of the early-age stress evolution of Ground granulated blast furnace slag (GGBFS) concrete, considering the development of autogenous deformation and creep. Temperature...

journal article 2022

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Interpretable Ensemble-Machine-Learning models for predicting creep behavior of concrete

Liang, M. (author), Chang, Z. (author), Wan, Z. (author), Gan, Y. (author), Schlangen, E. (author), Šavija, B. (author)

This study aims to provide an efficient and accurate machine learning (ML) approach for predicting the creep behavior of concrete. Three ensemble machine learning (EML) models are selected in this study: Random Forest (RF), Extreme Gradient Boosting Machine (XGBoost) and Light Gradient Boosting Machine (LGBM). Firstly, the creep data in...

journal article 2022

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Towards understanding deformation and fracture in cementitious lattice materials: Insights from multiscale experiments and simulations

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

Tailoring lattice structures is a commonly used method to develop lattice materials with desired mechanical properties. However, for cementitious lattice materials, besides the macroscopic lattice structure, the multi-phase microstructure of cement paste may have substantial impact on the mechanical responses. Therefore, this work proposes a...

journal article 2022

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Predicting early-age stress evolution in restrained concrete by thermo-chemo-mechanical model and active ensemble learning

Liang, M. (author), Chang, Z. (author), He, S. (author), Chen, Y. (author), Gan, Y. (author), Schlangen, E. (author), Šavija, B. (author)

Early-age stress (EAS) is an important index for evaluating the early-age cracking risk of concrete. This paper encompasses a thermo-chemo-mechanical (TCM) model and active ensemble learning (AEL) for predicting the EAS evolution. The TCM model provides the data for the AEL model. First, based on Fourier's law, Arrhenius’ equation, and rate...

journal article 2022

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Numerical simulation of elastic buckling in 3D concrete printing using the lattice model with geometric nonlinearity

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

This paper explores buildability quantification of randomly meshed 3D printed concrete objects by considering structural failure by elastic buckling. The newly proposed model considers the most relevant printing parameters, including time-dependent material behaviors, printing velocity, localized damage and influence of sequential printing...

journal article 2022

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3D concrete printing: Lattice modeling of structural failure considering damage and deformed geometry

Chang, Z. (author), Liang, M. (author), Xu, Y. (author), Schlangen, E. (author), Šavija, B. (author)

This research studies the impact of localized damage and deformed printing geometry on the structural failure of plastic collapse for 3D concrete printing (3DCP) using the lattice model. Two different approaches are utilized for buildability quantification: the (previously developed) load-unload method, which updates and relaxes the printing...

journal article 2022

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A discrete lattice model for assessment of buildability performance of 3D-printed concrete

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

In this work, the lattice model is applied to study the printing process and quantify the buildability (i.e., the maximum height that can be printed) for 3D concrete printing (3DCP). The model simulates structural failure by incorporating an element birth technique, time-dependent stiffness and strength, printing velocity, non-uniform...

journal article 2021