scholarly journals Investigating the Effect of CNTs on Early Age Hydration and Autogenous Shrinkage of Cement Composite

2021 ◽  
Vol 11 (12) ◽  
pp. 5545
Author(s):  
Byoungsun Park ◽  
Young Cheol Choi
Keyword(s):  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Cement Composite ◽  
Early Age ◽  
Cement Composites ◽  
Bulk Strain ◽  
Reinforced Cement ◽  
Internal Relative Humidity ◽  
Early Age Hydration ◽  
Walled Cnts

In this study, the effect of carbon nanotubes (CNTs) on the physical properties of cement composites was investigated. The mechanism of the change of autogenous shrinkage of CNTs-reinforced cement composites was also examined. In the experiments, ordinary Portland cement (OPC) and fly ash (FA) were used as binders, and 0.0, 0.1, 0.3, and 0.5% multi-walled CNTs (MWCNTs) were added to fabricate pastes. When the hydration heat was measured through isothermal calorimetry, it was found that CNTs accelerated the early age hydration of the pastes and that the hydration rate increased as the CNT content increased. The compressive strength was the highest when the CNT content was 0.1%. As the CNT content increased, the internal relative humidity (IRH) decreased and autogenous shrinkage showed a decreasing tendency. Through the analysis of the correlation between autogenous shrinkage and IRH, it was confirmed that the reduction in autogenous shrinkage due to the addition of CNTs resulted from the decrease in bulk strain.

scholarly journals Case Study on Early Age Shrinkage of Cement-based Composites

2015 ◽  
Vol 2 ◽  
pp. 79
Author(s):  
Andina Sprince ◽  
Leonids Pakrastinsh
Keyword(s):  
High Performance ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cement Composite ◽  
Early Age ◽  
Thin Walls ◽  
Reinforced Cement ◽  
Pva Fiber

The aim of this paper was to study the behaviour of new high-performance fibre-reinforced cement composite materials (FRCC) that are reinforced with polyvinyl alcohol (PVA) fibres. The shrinkage deformations at early age, the compressive strength and modulus of elasticity of the new compositions had been determined. Test results shows that the addition of PVA fiber 1.10% and 0.55% by weight of the cement has negligible influence on concrete drying shrinkage, however, it is affect the concrete plastic and autogenous shrinkage. The results of the experiments permitted the prediction of long-term deformations of the concrete. Wider use of this material permit the construction of sustainable next generation structures with thin walls and large spans that cannot be built using the traditional concrete.

Reinforced Cement Composites – Effect of Hybrid Fibres on Selected Properties

2015 ◽  
Vol 824 ◽  
pp. 179-183
Author(s):  
Dana Koňáková ◽  
Eva Vejmelková
Keyword(s):  
Mechanical Properties ◽  
Thermal Loading ◽  
Bending Strength ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Cement Composite ◽  
Polypropylene Fibre ◽  
Cement Composites ◽  
Matrix Density ◽  
Reinforced Cement

In this article selected properties of a glass and polypropylene fibre reinforced cement composite materials are studied. They are determined either after preceding thermal treatment or during thermal loading. Basic physical properties (in concrete terms bulk density, matrix density and open porosity), mechanical properties (in concrete terms tensile strength and bending strength) are determined after subjecting the specimens to the pre-heating temperatures of 600°C, 800°C and 1000°C. The linear thermal expansion coefficient is measured directly as functions of temperature up to 1000°C. The critical temperature for the glass and polypropylene fibre reinforced cement composite when most properties are worsening in a significant way is found apparently 500°C.

EFFECT OF RECYCLED MATERIALS ON THE TENSILE BEHAVIOR OF STEEL FIBER-REINFORCED CEMENT COMPOSITE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Sun-Woo Kim ◽  
Wan-Shin Park ◽  
Young-Il Jang ◽  
Yi-Hyun Nam ◽  
Sun-Woong Kim ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Steel Fiber ◽  
Cement Composite ◽  
Fine Aggregate ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Direct Tension ◽  
Recycled Materials ◽  
Reinforced Cement

Conventional cement composite is generally produced with ordinary Portland cement (OPC) as a binder. However, during manufacturing the cement composite, large amount of carbon dioxide (CO2) are emitted. Therefore, fly ash is proposed to be replaced to OPC in order to reduce CO2 emission of cement composites. For reinforcing fibers, micro steel fibers were used. For investigating mechanical properties of steel fiber-reinforced cement composites (SFRCCs), direct tension tests were conducted. The test results showed that fly ash improves tensile strength and ductility of SFRCCs. However, tensile strength of the SFRCC decreased as replacement ratio of recycled fine aggregate increased. The use of recycled materials in FRCC helps to save natural resources and promote sustainability in civil engineering materials.

scholarly journals Monitoring the early-age hydration of self-compacting concrete using ultrasonic p-wave transmission and isothermal calorimetry

2011 ◽  
Vol 44 (8) ◽  
pp. 1537-1558 ◽  
Author(s):  
Bram Desmet ◽  
Kelly Chrysanthe Atitung ◽  
Miguel Angel Abril Sanchez ◽  
John Vantomme ◽  
Dimitri Feys ◽  
...  
Keyword(s):  
Isothermal Calorimetry ◽  
Wave Transmission ◽  
P Wave ◽  
Early Age ◽  
Self Compacting Concrete ◽  
Early Age Hydration

scholarly journals Restrained Stress Development in Hardening Mortar Internally Cured with Superabsorbent Polymers under Autogenous and Drying Conditions

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 979
Author(s):  
Jung Heum Yeon
Keyword(s):  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Early Age ◽  
Shrinkage Cracking ◽  
Stress Development ◽  
Cracking Potential ◽  
Different Types ◽  
Internal Relative Humidity ◽  
Series Of Experiments ◽  
Drying Conditions

This study reports the results of a series of experiments, particularly paying attention to the early-age behavior and response of hardening mortars incorporating different types and contents of superabsorbent polymer (SAP) under autogenous (sealed) and drying shrinkage (unsealed) conditions. To achieve this primary aim, the effects of SAP type (i.e., cross-linking density and grain size) and content on the internal relative humidity (IRH) changes and corresponding free shrinkage behavior, restrained stress development, and cracking potential of the mortar were extensively measured and analyzed, along with their strength and set time properties. The results of this study have shown that the internal curing (IC) via SAP effectively counteracted the early-age residual stress build-up due to autogenous shrinkage, as many other former studies described. No or little tensile residual stresses due to autogenous shrinkage took place when more than 0.4% SAP was added, regardless of the SAP type. However, it should be mentioned that the addition of SAP, irrespective of its content and type, hardly improved the shrinkage cracking resistance of the mortar when directly exposed to drying environment at early ages.

Effect and Microscopic Mechanisms of Slag Micropowder on the Reinforcement of CaCO3 Whisker in Cement Composites

2011 ◽  
Vol 675-677 ◽  
pp. 529-535 ◽  
Author(s):  
Jian Qiang Wei ◽  
Ming Li Cao
Keyword(s):  
Cement Composite ◽  
Cement Matrix ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Slag Powder ◽  
Pull Out ◽  
Reinforced Cement ◽  
Powder Content

Whisker pull-out, which indicates that the interfacial bond strength of whiskers/cement is not high enough, is dominant in the microstructure of whisker-reinforced cement fractured surfaces. The weak interfacial bond of whiskers in cement matrix severely restrained the further improvement of properties. Superfine slag powder was used to modify and improve the strength and bond behavior of whisker-reinforced cement. Crystal structures, microcosmic appearances and characterizations of Slag Micro powder and the composite were studied by X-ray diffraction (XRD), and scan electron microscope (SEM/EDS), etc. Effect and mechanisms of different Slag powder content on the micro-structure and macro-properties of cement composite were investigated. The results show that Slag Micropowder can modify and improve the microstructure, interfacial and mechanical properties of whisker-reinforced cement.

scholarly journals Electrical, Piezoresistive and Electromagnetic Properties of Graphene Reinforced Cement Composites: A Review

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3220
Author(s):  
Shengchang Mu ◽  
Jianguang Yue ◽  
Yu Wang ◽  
Chuang Feng
Keyword(s):  
Material Properties ◽  
High Performance ◽  
Cement Composite ◽  
Electromagnetic Properties ◽  
Cement Matrix ◽  
Future Research ◽  
Cement Composites ◽  
Preparation Methods ◽  
Reinforced Cement ◽  
Filler Dispersion

Due to their excellent combination of mechanical and physical properties, graphene and its derivatives as reinforcements have been drawing tremendous attention to the development of high-performance and multifunctional cement-based composites. This paper is mainly focused on reviewing existing studies on the three material properties (electrical, piezoresistive and electromagnetic) correlated to the multifunction of graphene reinforced cement composite materials (GRCCMs). Graphene fillers have demonstrated better reinforcing effects on the three material properties involved when compared to the other fillers, such as carbon fiber (CF), carbon nanotube (CNT) and glass fiber (GF). This can be attributed to the large specific surface area of graphene fillers, leading to improved hydration process, microstructures and interactions between the fillers and the cement matrix in the composites. Therefore, studies on using some widely adopted methods/techniques to characterize and investigate the hydration and microstructures of GRCCMs are reviewed and discussed. Since the types of graphene fillers and cement matrices and the preparation methods affect the filler dispersion and material properties, studies on these aspects are also briefly summarized and discussed. Based on the review, some challenges and research gaps for future research are identified. This review is envisaged to provide a comprehensive literature review and more insightful perspectives for research on developing multifunctional GRCCMs.

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