scholarly journals Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount

2014 ◽  
Vol 65 ◽  
pp. 140-150 ◽  
Author(s):  
R. Yu ◽  
P. Spiesz ◽  
H.J.H. Brouwers
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Microstructure Development ◽  
Nano Silica ◽  
Ultra High Performance Concrete

scholarly journals Matrix Optimization of Ultra High Performance Concrete for Improving Strength and Durability

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6944
Author(s):  
Julio A. Paredes ◽  
Jaime C. Gálvez ◽  
Alejandro Enfedaque ◽  
Marcos G. Alberti
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Mercury Intrusion Porosimetry ◽  
High Performance Concrete ◽  
Silica Sand ◽  
Nano Silica ◽  
Ultra High Performance Concrete ◽  
Matrix Optimization ◽  
Binder Ratio ◽  
Strength And Durability

This paper seeks to optimize the mechanical and durability properties of ultra-high performance concrete (UHPC). To meet this objective, concrete specimens were manufactured by using 1100 kg/m3 of binder, water/binder ratio 0.20, silica sand and last generation of superplasticizer. Silica fume, metakaolin and two types of nano silica were used for improving the performances of the concrete. Additional mixtures included 13 mm long OL steel fibers. Compressive strength, electrical resistivity, mercury intrusion porosimetry tests, and differential and thermogravimetric thermal analysis were carried out. The binary combination of nano silica and metakaolin, and the ternary combination of nano silica with metakaolin and silica fume, led to the best performances of the UHPC, both mechanical and durable performances.

scholarly journals Evaluation of the nano silica and nano waste materials on the corrosion protection of high strength steel embedded in ultra-high performance concrete

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sahar A. Mostafa ◽  
Mohamed M. EL-Deeb ◽  
Ahmed A. Farghali ◽  
A. Serag Faried
Keyword(s):  
High Strength Steel ◽  
High Performance ◽  
Open Circuit Potential ◽  
High Performance Concrete ◽  
High Strength ◽  
Open Circuit ◽  
Nano Materials ◽  
Nano Silica ◽  
Ultra High Performance Concrete ◽  
Transfer Resistance

AbstractCorrosion resistance of high strength steel (HHS) embedded in ultra-high performance concrete (UHPC) immersed in 3.5% NaCl solution is evaluated in the absence and presence of nano silica (NS), nano glass waste (NGW), nano rice husk ash (NRHA) and nano metakaolin (NMK) using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) under normal and accelerated conditions. Data showed that the corrosion rate in the accelerated conditions is higher compared by the normal conditions due to the increasing in the rate of both anodic and cathodic reactions in the presence of anodic current. On the other hand, the presence of the studied nano materials decreases both the anodic and cathodic overpotentials, and shifts both the open circuit potential (Eocp) and corrosion potential (Ecorr) of HSS to more noble values, as well as decreases the values of the corrosion current densities (Icorr) in both normal and accelerated conditions. Furthermore, EIS analysis illustrates that the presence of these materials enhances both the concrete bulk resistance and the charge transfer resistance at HSS/UHPC interface, which retards the flow of the electrons between the anodic and cathodic sites, thus impeding the propagation of the corrosion process. The inhibitory effect of the studied nano materials for the corrosion of HSS is interpreted on the basis of the change in the microstructure and the compressive strength of the UHPC.

The influence of nano-silica and barite aggregate on properties of ultra high performance concrete

2016 ◽  
Vol 126 ◽  
pp. 147-156 ◽  
Author(s):  
Ksenija Janković ◽  
Srboljub Stanković ◽  
Dragan Bojović ◽  
Marko Stojanović ◽  
Lana Antić
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Nano Silica ◽  
Ultra High Performance Concrete

scholarly journals Matrix Optimization of Ultra High Performance Concrete for Improving Strength and Durability

2021 ◽  
Author(s):  
Julio Paredes ◽  
Jaime C. Gálvez ◽  
Alejandro Enfedaque ◽  
Marcos G. Alberti
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Mercury Intrusion Porosimetry ◽  
High Performance Concrete ◽  
Silica Sand ◽  
Nano Silica ◽  
Ultra High Performance Concrete ◽  
Matrix Optimization ◽  
Binder Ratio ◽  
Strength And Durability

This paper seeks to optimize the mechanical and durability properties of ultra-high performance concrete (UHPC). To meet this objective, concrete specimens were manufactured by using 1,100 kg/m3 of binder, water/binder ratio 0.20, silica sand and last generation of superplasticizer. Silica fume, metakaolin and two types of nano silica were used for improving the performances of the concrete. Additional mixtures included 13mm long OL steel fibers. Compressive strength, electrical resistivity, mercury intrusion porosimetry tests and differential and thermogravimetric thermal analysis were carried out. The binary combination of nano silica and metakaolin, and the ternary combination of nano silica with metakaolin and silica fume, led to the best performances of the UHPC, both mechanical and durable performances.

scholarly journals Experimental and Numerical Study of Nano-Silica Additions on the Local Bond of Ultra-High Performance Concrete and Steel Reinforcing Bar

2018 ◽  
Vol 3 (12) ◽  
pp. 1339 ◽  
Author(s):  
Ahad Amini Pishro ◽  
Xiong Feng
Keyword(s):  
Numerical Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Numerical Study ◽  
Concrete Specimen ◽  
Bond Stress ◽  
Nano Silica ◽  
Ultra High Performance Concrete ◽  
Reinforcing Bar ◽  
Micro Silica

Micro-silica is widely used as an additive to cement in producing high performance concrete. This matter is used to enhance the strength and efficiency of concrete. Recently, due to the development of advanced nano-technology, nano-silica has been produced with particle sizes smaller than micro-silica and higher pozzolanic activity. Studies show that addition of nano-silica into cement-based materials improves their mechanical properties. Considering the unique characteristics of nano-silica, it seems that this material can be used in ultra-high performance concrete (UHPC). Therefore, further studies are needed on how the local bond and bond stress of steel reinforcing bar and UHPC containing nano-silica would be effected. In the present study, after preparing the mix designs and proposed specimens, the effects of various parameters on the local bond of steel reinforcing bars and UHPC containing nano-silica were examined by pullout experiments. In this research, we have numerically investigated the bond strength using numerical methods and calibration of the ABAQUS results in addition to its experimental study of ultra-high performance concrete and steel reinforcement. In numerical analysis, the concrete damage plasticity method was used to simulate the nonlinear behavior of concrete and its strain softness. Comparing between numerical and experimental analysis results shows that numerical analysis with high precision can predict the bond stress, bond load, and concrete specimen fracture mode.

scholarly journals Influence of Nanoparticles from Waste Materials on Mechanical Properties, Durability and Microstructure of UHPC

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4530 ◽  
Author(s):  
Sahar A. Mostafa ◽  
Ahmed S. Faried ◽  
Ahmed A. Farghali ◽  
Mohamed M. EL-Deeb ◽  
Taher A. Tawfik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Rice Husk ◽  
High Performance ◽  
Rice Husk Ash ◽  
High Performance Concrete ◽  
Waste Materials ◽  
Nano Silica ◽  
Ultra High Performance Concrete ◽  
X Ray

This investigation presents the influence of various types of nanoparticles on the performance of ultra high performance concrete (UHPC). Three nanoparticles from waste materials include nano-crushed glass, nano-metakaolin, nano-rice husk ash were prepared using the milling technique. In addition, nano-silica prepared using chemical method at the laboratory is implemented to compare the performance. Several UHPC mixes incorporating different dosages of nanoparticles up to 5% are prepared and tested. Mechanical properties, durability as well as the microstructure of UHPC mixes have been evaluated in order to study the influence of nanoparticles on the hardened characteristics of UHPC. The experimental results showed that early strength is increased by the incorporation of nanomaterials, as compared to the reference UHPC mix. The incorporation of 3% nano-rice husk ash produced the highest compressive strength at 91 day. Microstructural measurements using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), and Thermogravimetric Analysis (TGA) confirm the role of nanomaterials in densifying the microstructure, reducing calcium hydroxide content as well as producing more C-S-H, which improves the strength and reduces the absorption of UHPC. Nanoparticles prepared from waste materials by the milling technique are comparable to chemically prepared nanosilica in improving mechanical properties, refining the microstructure and reducing the absorption of UHPC.

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