Synthesis, solubility and thermodynamic properties of N-A-S-H gels with various target Si/Al ratios

The synthesis of N-A-S-H gel with high Si/Al ratios (>2) has been rarely reported in the literature, leaving the establishment of a reliable synthesis route as an open challenge. This paper aims to synthesize N-A-S-H gels with Si/Al ratios ranging from 1 to 3 and establish their thermodynamic database. The effects of reaction temperature,...

Degradation of alkali-activated slag subjected to water immersion

In this study, the impacts of tap water immersion on the pore solution, phase assemblages, gel chemistry and structure, and pore structure of alkali-activated slag (AAS) pastes were studied. AAS degrades under such condition and the potential mechanisms can be concluded as lower reaction rates, gel decomposition and carbonation. The leaching...

Autogenous shrinkage of alkali-activated slag: A critical review

This paper provides a critical review on autogenous shrinkage of alkali-activated slag (AAS). It is reported that AAS paste, mortar, and concrete generally show larger autogenous shrinkage than Portland cement (PC) counterparts. Self-desiccation is the main driving force of the autogenous shrinkage of hardened AAS, but other mechanisms also...

A molecular dynamics study of N–A–S–H gel with various Si/Al ratios

In this paper, the atomic structures of sodium aluminosilicate hydrate (N–A–S–H) gels with different Si/Al ratios are studied by molecular dynamics simulation. An N–A–S–H gel model was obtained from the polymerization of Si(OH)₄ and Al(OH)₃ monomers with the use of a reactive force field (ReaxFF). The simulated atomic...

Characterizing the Effects of Al(OH)3 and Mg(OH)2 on Reaction Products and Drying Shrinkage Characteristics of Alkali-activated Slag

This study is undertaken to explore the relationship between the reaction products and the drying shrinkage of alkali-activated slag (AAS) with the varying hydroxide dosage. AAS pastes were firstly produced with either Al(OH)3 or Mg(OH)2 to investigate the effects of hydroxide on the composition of reaction products and the drying shrinkage of...

A molecular dynamics study of N-A-S-H gel with various Si/Al ratios

The understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the...

A molecular dynamics study of N-A-S-H gel with various Si/Al ratios

The understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the...

Prediction of the autogenous shrinkage and microcracking of alkali-activated slag and fly ash concrete

This study aims to predict the autogenous shrinkage of alkali-activated concrete (AAC) based on slag and fly ash. A variety of analytical and numerical models are available for the prediction of autogenous shrinkage of ordinary Portland cement (OPC) concrete, but these models are found to show dramatic discrepancies when applied for AAC due...

Effect of metakaolin on the autogenous shrinkage of alkali-activated slag-fly ash paste

The high autogenous shrinkage of alkali-activated materials made from slag and fly ash is recognised as a major drawback with regard to the use as construction materials. In this study, metakaolin was introduced into the alkali-activated slag-fly ash (AASF) paste to mitigate the autogenous shrinkage. The shrinkage mitigation mechanism of...

Early-age properties of alkali-activated slag and glass wool paste

In this study, glass wool waste was utilized by means of alkali-activation with blast furnace slag. Reaction kinetics, workability, mechanical properties and autogenous shrinkage of alkali-activated slag and glass wool were comprehensively studied. Results indicated an optimal modulus (SiO₂/Na₂O) of the activator related...

Evaluation of short-term streamflow prediction methods in Urban river basins

Efficient and accurate streamflow predictions are important for urban water management. Data-driven models, especially neural network (NN) models can predict streamflow fast, while the results are uncertain in some complex river systems. Physically based models can reveal the underlying physics, but it is relatively slow and computationally...

Numerical analysis of the effect of the scan strategy on the residual stress in the multi-laser selective laser melting

The inevitably formed residual stress in the Selective Laser Melting (SLM) process leads to distortion, crack and even delamination of the workpiece. Single laser is commonly applied during SLM processing. However, its productivity is much lower than multiple lasers. In addition, the research of residual stress with multi-laser condition...

A low-autogenous-shrinkage alkali-activated slag and fly ash concrete

Alkali-activated slag and fly ash (AASF) materials are emerging as promising alternatives to conventional Portland cement. Despite the superior mechanical properties of AASF materials, they are known to show large autogenous shrinkage, which hinders the wide application of these eco-friendly materials in infrastructure. To mitigate the...

SlimML: Removing Non- critical Input Data in Large-scale Iterative Machine Learning

The core of many large-scale machine learning (ML) applications, such as neural networks (NN), support vector machine (SVM), and convolutional neural network (CNN), is the training algorithm that iteratively updates model parameters by processing massive datasets. From a plethora of studies aiming at accelerating ML, being data...

Mitigating the autogenous shrinkage of alkali-activated slag by metakaolin

This study investigates the effectiveness of metakaolin (MK)in mitigating the autogenous shrinkage of alkali-activated slag (AAS). It is found that the autogenous shrinkage of AAS paste can be reduced by 40% and 50% when replacing 10% and 20% slag with MK, respectively. By providing additional Si and Al, and decreasing the pH of the pore...

Chemical deformation of metakaolin based geopolymer

Chemical deformation (chemical shrinkage/expansion), the absolute volume change during reactions, is a key parameter influencing the volume stability, especially the autogenous deformation of a binder material. This work, for the first time, reports an in-depth investigation on the chemical deformation of metakaolin based geopolymer (MKG)....

Reduced thermal conductivity by nanoscale intergrowths in perovskite like layered structure La2Ti2O

The effect of substitution and oxidation-reduction on the thermal conductivity of perovskite-like layered structure (PLS) ceramics was investigated in relation to mass contrast and non-stoichiometry. Sr (acceptor) was substituted on the A site, while Ta (donor) was substituted on the B site of La2Ti2O7. Substitution in PLS materials creates...