Journal ArticleDOI
Properties of interfacial transition zones in recycled aggregate concrete tested by nanoindentation
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TLDR
In this paper, the properties of new Interfacial Transition Zone (ITZ) and old ITZ in Recycled Aggregate Concrete (RAC) were investigated by atomic force microscopy (AFM), Scanning Electron Microscopy (SEM) and nanoindentation.Abstract:
The properties of new Interfacial Transition Zone (ITZ) and old ITZ in Recycled Aggregate Concrete (RAC) were investigated by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and nanoindentation. From the SEM images, obvious voids and high concentration of calcium hydroxide can be found in both old ITZ and new ITZ in RAC. Based on the nanoindentation study, it is indicated that the thicknesses of old and new ITZs are in the range 40–50 μm and in the range 55–65 μm, respectively. It is also found that the average indentation modulus of old ITZ is 70–80% of that of old paste matrix, while the average indentation modulus of new ITZ is 80–90% of that of new paste matrix. Additionally, the influences of mix proportion, aggregate types and hydration age on the properties of ITZs in RAC are discussed in this study.read more
Citations
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Journal ArticleDOI
Effect of Interfacial Transition Zone on the Carbonation of Cement-Based Materials
TL;DR: In this paper, the effects of the interfacial transition zone (ITZ) on the carbonation of cement-based material were investigated. But the authors dealt with an analysis of the impact of the IZ on the performance of the cement carbonation process.
Journal ArticleDOI
Thermo-mechanical assessment of concrete microcracking damage due to early-age temperature rise
TL;DR: In this paper, a two-phase micromechanical model was used to compute thermal stresses based on both coefficient of thermal expansion (CTE) and elastic Young's modulus (E ) mismatches between aggregates and the cementitious matrix.
Journal ArticleDOI
Influence of recycled fine aggregate on microstructure and hardened properties of concrete
TL;DR: In this article, the authors investigated the effect of commercially produced recycled fine aggregate (RFA) on the compressive, tensile and microstructural behaviour of recycled aggregate concrete (RAC) and found that RFA as a substitute for natural sand at various volume replacement levels (0, 25, 50, 75, 75 and 100%) was studied.
Journal ArticleDOI
Microstructural and micromechanical characteristics of ultra-high performance concrete with superabsorbent polymer (SAP)
TL;DR: In this article, the hydration product, C-S-H density, and pore structure at different layers from the drying surface were measured, and the zone affected by the released internal curing water from SAP was identified by assessing the nanoindentation modulus.
Journal ArticleDOI
Effect of Surface Modifications of Recycled Concrete Aggregate on Concrete Properties
Jozef Junak,Alena Sicakova +1 more
TL;DR: In this article, two different ways of treatment of the RCA with geopolymer slurry were applied to reduce its negative impact on the concrete properties, and the results of density, total water absorption, and compressive strength in periods of 28, 90, 180, and 365 days of curing were evaluated.
References
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Journal ArticleDOI
An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments
Warren C. Oliver,George M. Pharr +1 more
TL;DR: In this paper, the authors used a Berkovich indenter to determine hardness and elastic modulus from indentation load-displacement data, and showed that the curve of the curve is not linear, even in the initial stages of the unloading process.
Journal ArticleDOI
The effect of two types of C-S-H on the elasticity of cement-based materials: Results from nanoindentation and micromechanical modeling
TL;DR: In this paper, a two types of calcium-silicate-hydrate (C-S-H) exist in cement-based materials, but less is known about how the two types affect the mechanical properties.
Journal ArticleDOI
The Interfacial Transition Zone (ITZ) Between Cement Paste and Aggregate in Concrete
TL;DR: In this article, the authors describe the so called interfacial transition zone (ITZ) in concrete as the region of the cement paste around the aggregate particles, which is perturbed by the presence of the aggregate, and show that the higher porosity present initially is significantly diminished by the migration of ions during hydration.
Journal ArticleDOI
Effect of microstructure of ITZ on compressive strength of concrete prepared with recycled aggregates
TL;DR: In this article, the influence of these aggregates (recycled and natural) on the microstructure and compressive strength of the new concrete were studied, and the results are explained by the differences in porosity and pore structure of the two types of aggregates, and possible interactions between the aggregates and the cement paste.
Journal ArticleDOI
An overview of study on recycled aggregate concrete in China (1996-2011)
TL;DR: A series of investigations on the mechanical property, durability, and structural performance of recycled aggregate concrete (RAC) have been carried out in the past 15 years (1996-2011) in China.
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