A conceptual design of two-stream alkali-activated materials

To properly control the reaction kinetics and fresh properties evolution in conventional alkali-activated materials (AAMs), a conceptual design of two-stream AAMs has been proposed in this study. This is achieved by dividing the solid and liquid components in AAMs, including blast furnace slag (BFS) and electric arc furnace slag (EFS)...

Interpretation of the early stiffening process in alkali-activated slag pastes

To better understand early stiffening of AAS pastes, distinctive microstructural features by varying the silicate modulus (Ms) have been visualized with in-situ microscopy. In addition, the activation reaction was monitored with multiple approaches, while solid and liquid phases in hydrating AAS were characterized separately. In silicate...

Coalescence kinetics and microstructure evolution of Cu nanoparticles sintering on substrates: a molecular dynamics study

Nano copper sintering technology has great potential to be widely applied in the wide-bandgap semiconductor packaging. In order to investigate the coalescence kinetics of copper nano particles for this application, a molecular dynamic (MD) simulation was carried out at low temperature on a special model containing two substrate and multiple...

Hydrogenated Boron Phosphide THz-Metamaterial-Based Biosensor for Diagnosing COVID-19: A DFT Coupled FEM Study

Recent reports focus on the hydrogenation engineering of monolayer boron phosphide and simultaneously explore its promising applications in nanoelectronics. Coupling density functional theory and finite element method, we investigate the bowtie triangle ring microstructure composed of boron phosphide with hydrogenation based on structural and...

Rheology of alkali-activated slag pastes: New insight from microstructural investigations by cryo-SEM

This study aims to interpret the early-stage rheology of alkali-activated slag (AAS) paste from microstructure perspectives. The microstructures visualized by cryogenic scanning electron microscopy (cryo-SEM) revealed the essential distinction between hydroxide and silicate-activated slag pastes. The hydroxide-based mixture showed typical...

Modelling of microstructure of asr influenced cement-based materials

ASR (alkali-silica reaction) is one of the toughest durability problems in engineering. However, the damage induced by ASR is still fairly unpredictable due to the lack of microstructural information of cement-based materials affected by ASR, while the microstructure determines the global performance. In order to fill this gap, a multiscale...

3d microstructure simulation of reactive aggregate in concrete from 2d images as the basis for asr simulation

The microstructure of alkali-reactive aggregates, especially the spatial distribution of the pore and reactive silica phase, plays a significant role in the process of the alkali silica reaction (ASR) in concrete, as it determines not only the reaction front of ASR but also the localization of the produced expansive product from where the...

Fracture properties and microstructure formation of hardened alkali-activated slag/fly ash pastes

This study presents a comprehensive experimental investigation on the fracture properties of hardened alkali-activated slag/fly ash (AASF) pastes in relation to the microstructure formation and reaction product composition. The main reaction product in AASF is C-(N-)A-S-H gel along with minor hydrotalcite phase, with the polymerization of C-...

GeoMicro3D: A novel numerical model for simulating the reaction process and microstructure formation of alkali-activated slag

For the first time, this study developed a novel model, named GeoMicro3D, to simulate the reaction process and microstructure formation of alkali-activated slag. The GeoMicro3D model consists of four modules that are designed to simulate, respectively: (i) the initial spatial distribution of real-shape slag particles in alkaline activator, ...

Internal curing of alkali-activated slag-fly ash paste with superabsorbent polymers

This study investigates the influences of internal curing on reducing the autogenous shrinkage of alkali-activated slag/fly ash (AASF) paste. The influences of internal curing with superabsorbent polymers (SAPs) on the reactions and microstructure of AASF paste are investigated. It is found that the SAPs absorb liquid mainly before the...

Extension of the Hymostruc3D model for simulation of hydration and microstructure development of blended cements

The HYMOSTRUC3D model has been used successfully to predict hydration and microstructure development of pure Portland cement paste. In recent years, a number of numerical models were proposed for optimizing the use of supplementary cementitious materials. Also HYMOSTRUC3D was extended for simulating the hydration and microstructure development...

Microstructure-based prediction of the elastic behaviour of hydrating cement pastes

The development of the elastic properties of a hardening cement paste results from the microstructural evolution due to cement hydration. The elastic behaviour of cement paste can be predicted by a combination of the hydration model and micromechanical analysis, which originates from a microstructural representative volume where the elastic...

Waste glass as partial mineral precursor in alkali-activated slag/fly ash system

The feasibility of a waste glass powder residue (GP) from glass recycling as partial mineral precursor to produce alkali-activated materials is investigated. GP served as powder coal fly ash (PCFA) replacement within a reference system composed of 50% PCFA and 50% ground granulated blast furnace slag (GGBS). Compared with PCFA, GP was better...

Experimental study on pore connectivity and its influence on chloride transport in saturated cementitious system

The purpose of this paper is to investigate the pore connectivity and its influence on chloride transport property in cementitious materials under saturated condition. Mercury intrusion porosimetry experiment was carried out on a variety of hydrated cement pastes curing up to one year. By repeating pressurization-depressurization cycles, pore...

Microstructure Analysis of Heated Portland Cement Paste

When a concrete structure is exposed to high temperature, the mechanical damage and chemical transformation take place simultaneously, which will change the microstructure of material. On the other hand, the mechanical properties and transport properties depend on the development of microstructure of cement paste. In order to study the...

Numerical simulation of the hydration process and the development of microstructure of self-compacting cement paste containing limestone as filler

Experimental Study and Numerical Simulation of the Development of the Microstructure and Permeability of Cementitious Materials

The aim of this thesis was to investigate and to simulate the development of the microstructure, porosity and permeability in hardening cement-based materials. Based on experimental information and the cement hydration model HYMOSTRUC, the microstructural details including porosity, connectivity of pores and pore size distribution were...