Effects of a size in bundled fibers on the interfacial zone between the fibers and the cement paste matrix

1994 ◽  
Vol 24 (4) ◽  
pp. 695-703 ◽  
Author(s):  
Shin-ichi Igarashi ◽  
Mitsunori Kawamura
Keyword(s):  
Cement Paste ◽  
Interfacial Zone

scholarly journals Effect of Carbon Nanofiber Clustering on the Micromechanical Properties of a Cement Paste

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
Lesa Brown ◽  
Catherine S. Stephens ◽  
Paul G. Allison ◽  
Florence Sanchez
Keyword(s):  
Cement Paste ◽  
Mechanical Response ◽  
Carbon Nanofiber ◽  
Homogenization Method ◽  
Indentation Modulus ◽  
Interfacial Zone ◽  
Micromechanical Properties ◽  
Significant Interest ◽  
Low Stiffness ◽  
Portland Cement Paste

The use of carbon nanofibers (CNFs) in cement systems has received significant interest over the last decade due to their nanoscale reinforcing potential. However, despite many reports on the formation of localized CNF clusters, their effect on the cement paste micromechanical properties and relation to the mechanical response at the macroscopic scale are still not fully understood. In this study, grid nanoindentation coupled with scanning electron microscopy and energy dispersive spectroscopy was used to determine the local elastic indentation modulus and hardness of a portland cement paste containing 0.2% CNFs with sub-micro and microscale CNF clusters. The presence of low stiffness and porous assemblage of phases (modulus of 15–25 GPa) was identified in the cement paste with CNFs and was attributed primarily to the interfacial zone surrounding the CNF clusters. The CNFs favored the formation of higher modulus C–S–H phases (>30 GPa) in the bulk paste at the expense of the lower stiffness C–S–H. Nanoindentation results combined with a microscale–macroscale upscaling homogenization method further revealed an elastic modulus of the CNF clusters in the range from 18 to 21 GPa, indicating that the CNF clusters acted as compliant inclusions relative to the cement paste.

A Method for Estimating the Dynamic Moduli of Cement Paste-Aggregate Interfacial Zones in Mortar

1994 ◽  
Vol 370 ◽  
Author(s):  
Menashi D. Cohen ◽  
Turng-Fang F. Lee ◽  
Ariel Goldman
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Cement Paste ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Dynamic Shear Modulus ◽  
Interfacial Zone ◽  
Dynamic Moduli ◽  
Dynamic Modulus Of Elasticity ◽  
Cement Mortars

AbstractThe objective of this paper is to propose a method to estimate the average values of the dynamic modulus of elasticity and the dynamic shear modulus of cement paste-aggregate interfacial zones in mortar by applying the Logarithmic Mixture Rule (LMR). Both portland cement mortars (PC mortars) and portland cement mortars with silica fume (SF mortars) are investigated and compared, The influence of silica fume on the dynamic moduli of interfacial zone is also examined. Results indicate that for the specific ingredients and mix design used, the dynamic modulus of elasticity of interfacial zone falls between 0.4 and 2.0 (×10 6 psi) for PC mortar and 1.2 to 2.2 (× 106 psi) for SF mortar. These values are lower than the values obtained for PC mortar (4.2 ×106 psi), PC paste (2.7 ×106 psi), SF mortar (4.4 ×106 psi), and SF paste (2.5 × 106 psi).

Water Absorbing and Releasing of Lightweight Aggregate and its Influence on Frost-Resistance of Combined Aggregate Concrete

2011 ◽  
Vol 217-218 ◽  
pp. 51-56 ◽  
Author(s):  
Li Xiong Gao ◽  
Li Juan Kong ◽  
Yong Ge
Keyword(s):  
Water Absorption ◽  
Cement Paste ◽  
Frost Resistance ◽  
Lightweight Aggregate ◽  
High Water ◽  
Interfacial Zone ◽  
Aggregate Concrete ◽  
High Water Absorption ◽  
Dense Shell ◽  
Curing Age

Water absorbing and releasing property of lightweight aggregate (LWA) in concrete and its influence on microstructure of interfacial zone as well as frost-resistance of combined aggregate prepared with different water absorption LWA and w/b ratios were investigated. The results show that, as for concrete with low w/b ratio, the 28d frost-resistance of concrete prepared with high water absorption LWA is worse, however with the increase of curing age, the 90d frost-resistance of concrete improves obviously, which is due to the water releasing of LWA that leads to the recovery of its air entraining effect as well as the densification and thicken of interfacial zone. So the LWA with moderate water absorption should be selected to prepare the low w/b ratio concrete. As for concrete with high w/b ratio, the frost-resistance of concrete prepared with low water absorption LWA is the best. This is account for the dense shell of ceramsite that could reduce the soakage from loose cement paste under frozen pressure.

Digital simulation of the aggregate–cement paste interfacial zone in concrete

1991 ◽  
Vol 6 (1) ◽  
pp. 196-201 ◽  
Author(s):  
Edward J. Garboczi ◽  
Dale P. Bentz
Keyword(s):  
Cement Paste ◽  
Digital Simulation ◽  
Particle Packing ◽  
Diffusion Reaction ◽  
Interfacial Region ◽  
Interfacial Zone ◽  
Two Dimensional ◽  
Portland Cement Concrete ◽  
Quantitative Image ◽  
Characteristic Features

Researchers using backscattered scanning electron microscopy, along with quantitative image analysis techniques, have clearly demonstrated the existence of a highly porous interfacial region between aggregate particles and the cement paste matrix in ordinary Portland cement concrete. This paper presents the results of a digital-image-based simulation model of this interfacial zone. A dissolution-diffusion-reaction-like cycle of hydrating cement particles is directly simulated using cement particles packed around a simple nonreactive aggregate particle. The model is two-dimensional, as we are comparing to experimental results obtained on two-dimensional images of polished sections. The qualitative features seen experimentally, such as large amounts of porosity and calcium hydroxide in the interfacial zone, are accurately reproduced. A new mechanism, one-sided growth, is proposed, along with the more usual particle-packing ideas, as an explanation of the origin of the characteristic features of the interfacial zone.

The Effect of Bond Characteristics between Steel Slag Fine Aggregate and Cement Paste on Mechanical Properties of Concrete and Mortar

1987 ◽  
Vol 114 ◽  
Author(s):  
Wang Yuji
Keyword(s):  
Mechanical Properties ◽  
Cement Paste ◽  
Steel Slag ◽  
Fine Aggregate ◽  
Interfacial Zone ◽  
Curing Time ◽  
Natural Sand ◽  
Concentration Of Ions ◽  
Hydrated Products ◽  
Bond Characteristics

ABSTRACTThe ordinary fine aggregate in concrete has been replaced by ground and sieved steel slag fine aggregate, treated and exposed to air for three months. Compared with concrete made from natural sand, properties such as compressive strength, flexural strength, elastic modulus, permeability and abrasion resistance are considerably improved. The improvement increases with a decrease in w/c ratio, an increase in curing time and an increase in the replacement weight of sand. These results are due to the fact that the steel slag contains some active minerals such as C3S, C2S, C4AF, etc., and shows favorable surface physical characteristics that improve the bond between steel slag particles and cement paste. The results of XRD, SEM and EPM microhardness showed that there are heavier concentration of ions, with finer crystals and a lower degree of CH orientation at the interfacial zone between steel slag particles and cement paste. The study also found small cementitious and fibrous C-S-H crystals growing from the fine aggregate, which are linked with hydrated products from cement paste making the bond and structural characteristic more favorable with cement. The steel slag fine aggregate is an active mineral similar to cement. The bond between the aggregate and cement paste is strengthened both physically and chemically.

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