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BUILDER ◽  
2019 ◽  
Vol 258 (1) ◽  
pp. 65-67 ◽  
Author(s):  
Milena Kucharska
Keyword(s):  
Bond Strength ◽  
Silica Fume ◽  
High Performance ◽  
Reinforcing Bars ◽  
Bond Quality ◽  
Self Compacting Concrete ◽  
The Impact

The paper analyses the impact of casting direction of self-compacting concrete (SCC) on its bond quality to steel reinforcing bars. Tests were performed on high performance self-compacting concretes with different amount of silica fume to cement mass. Experiment was carried out on 480 mm height specimens, which allowed determining changes of bond condition along its height. The ribbed reinforcing bars have been placed perpendicularly to the direction of casting. Casting was performed from two points – from the bottom and the top of the form. Research has shown that casting from the bottom of the form improves bond strength and quality.

Investigation of bond between lap-spliced steel bar and self-compacting concrete: The role of silica fume

2010 ◽  
Vol 37 (3) ◽  
pp. 420-428 ◽  
Author(s):  
Mehmet Karatas ◽  
Kazim Turk ◽  
Zulfu C. Ulucan
Keyword(s):  
Bond Strength ◽  
Silica Fume ◽  
Full Scale ◽  
Reinforcing Bars ◽  
Self Compacting Concrete ◽  
Normal Concrete ◽  
Steel Bar ◽  
Normalized Bond Strength ◽  
Constant Moment

In this study, normal concrete (NC) and four types of self-compacting concrete (SCC), in which cement was partially replaced by 5%, 10%, 15%, and 20% of silica fume (SF), were used to evaluate the effect of SF content on the bond strength of tension lap-spliced bars embedded in NC and SCC specimens. Therefore, 15 full-scale beam specimens (2000 × 300 × 200 mm3) were tested and 20 mm reinforcing bars were used with a 300-mm splice length as tension reinforcement. Each beam was designed with bars spliced in a constant moment region at midspan. It was found that the bond strength of the reinforcement embedded in SCC beams was higher than that of the reinforcement in NC beams, whilst the bond strength increased with increase in the replacement of cement by SF from 5% to 10%. Moreover, the beam specimens produced from SCC containing 5% SF had the highest normalized bond strength of 1.07 followed by SCC beams with 10% SF, 15% SF, NC beams, and 20% SF.

Mechanical and durability characteristics of high performance self-compacting concrete containing flyash, silica fume and graphene oxide

2021 ◽  
Vol 43 ◽  
pp. 2361-2367
Author(s):  
Damma Manikanta ◽  
Durga Prasad Ravella ◽  
Sri Rama Chand M. ◽  
Janardhan Yadav M.
Keyword(s):  
Graphene Oxide ◽  
Silica Fume ◽  
High Performance ◽  
Self Compacting Concrete

scholarly journals Investigation of the Impact of Micro-Structuring on the Bonding Performance of Beechwood (Fagus Sylvatica L.)

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 113
Author(s):  
Destin Bamokina Moanda ◽  
Martin Lehmann ◽  
Peter Niemz
Keyword(s):  
Bond Strength ◽  
Waiting Time ◽  
Type I ◽  
Bond Quality ◽  
Structured Surfaces ◽  
Structured Surface ◽  
Bonding Performance ◽  
Delamination Resistance ◽  
Micro Structuring ◽  
The Impact

Although glueing softwood is well mastered by the industry, predicting and controlling bond quality for hardwood is still challenging after years of research. Parameters such as the adhesive type, resin–hardener ratio, and the penetration behaviour of the wood are determinants for the bond quality. The aim of this work was to assess to what extent the glueing behaviour of beechwood can be improved by using structural planing. The different surfacing methods were characterised by their roughness. The bond strength of the micro-structured surfaces was determined according to EN 302-1, and the delamination resistance was tested as indicated by EN 302-2 for type I adhesives. Micro-structured surfaces were compared with different surfaces (generated by surfacing methods such as dull/sharp planing and sanding). In dry test conditions, all surfacing methods gave satisfying results. In the wet stage, the bond strength on the finer micro-structured surface slightly outperformed the coarse structure surface. For the delamination resistance, a clear improvement could be observed for melamine-formaldehyde-bonded specimens since, when using the recommended amount of adhesive, micro-structured surfaces fulfilled the requirements. Nevertheless, structural planing cannot lead to a reduction in the applied grammage since no sample with a smaller amount fulfilled EN 302-2 requirements even by observing the recommended closed assembly waiting time. Adhesion area enlargement of the micro-structuring is minor. The good delamination performance without waiting time (CAT) is not caused by surface enlargement, since finer micro-structured surface with negligible area increase and delivered even better delamination resistance. Subsurface analysis should be carried out to thoroughly investigate this phenomenon.

Quasi-Static Lap Shear and Dynamic Impact of High Performance VHB™ Acrylic Foam and Adhesive Transfer Tape Bonded Aluminum Joints Subjected to Environmental Degradation

2005 ◽  
Author(s):  
Manoj Anakapalli ◽  
P. Raju Mantena ◽  
Ahmed Al-Ostaz ◽  
S. Jimmy Hwang
Keyword(s):  
High Performance ◽  
Shear Failure ◽  
Electrochemical Impedance ◽  
Impact Load ◽  
Bond Quality ◽  
Dynamic Impact ◽  
Impulse Frequency ◽  
Lap Shear ◽  
Failure Loads ◽  
The Impact

A range of 3M™ VHB™ acrylic foam tapes and high performance adhesive transfer tapes were used to bond 1” × 1/8″ (25.4 mm × 3.175 mm) aluminum 2024 T-4 adherends in single-lap joint (SLJ) and three-point end-notched flexure (ENF) configurations. Three types of 0.045” thick double-coated acrylic foam tapes: Foam 41, 50 and 52 (firm, soft and softer), and three types of adhesive transfer tapes: Adhesives 69, 73 and 85 (0.005”, 0.01” and 0.005” thick, respectively) were used for this study. The samples were subjected to two types of aggressive environments simulating extreme service conditions: freeze-thaw cycling from 10°F to 50°F at 6 cycles per day (ASTM C666 Procedure A) for 21 days with samples immersed in water; heat-cool cycling (with 90% of maximum recommended temperature by the manufacturer of both acrylic foam and adhesive transfer tapes attained at 70% relative humidity) and 3 cycles per day for 21 days. Initially the impulse-frequency response vibration and electrochemical impedance spectroscopy (EIS) techniques were used for monitoring bond quality nondestructively and selecting the best out of 250 fabricated samples. After obtaining baseline data, the specimens were subjected to quasi-static lap-shear and dynamic impact loading to compare their lap-shear failure loads and shear energy along with the impact load and energy absorbed.

scholarly journals Production of Ultra-High-Performance Concrete with Low Energy Consumption and Carbon Footprint Using Supplementary Cementitious Materials Instead of Silica Fume: A Review

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8291
Author(s):  
Mays A. Hamad ◽  
Mohammed Nasr ◽  
Ali Shubbar ◽  
Zainab Al-Khafaji ◽  
Zainab Al Masoodi ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Cement Production ◽  
Granulated Blast Furnace Slag ◽  
The Impact

The increase in cement production as a result of growing demand in the construction sector means an increase in energy consumption and CO2 emissions. These emissions are estimated at 7% of the global production of CO2. Ultra-high-performance concrete (UHPC) has excellent mechanical and durability characteristics. Nevertheless, it is costly and affects the environment due to its high amount of cement, which may reach 800–1000 kg/m3. In order to reduce the cement content, silica fume (SF) was utilized as a partial alternative to cement in the production of UHPC. Nevertheless, SF is very expensive. Therefore, the researchers investigated the use of supplementary cementitious materials cheaper than SF. Very limited review investigates addressed the impact of such materials on different properties of UHPC in comparison to that of SF. Thus, this study aims to summarize the effectiveness of using some common supplementary cementitious materials, including fly ashes (FA), ground granulated blast furnace slag (GGBS), metakaolin (MK) and rice husk ashes (RHA) in the manufacturing of UHPC, and comparing the performance of each material with that of SF. The comparison among these substances was also discussed. It has been found that RHA is considered a successful alternative to SF to produce UHPC with similar or even higher properties than SF. Moreover, FA, GGBS and MK can be utilized in combination with SF (as a partial substitute of SF) as a result of having less pozzolanic activity than SF.

Impact of pressing regime and substrate type on bond quality of decorative veneer

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2668-2679
Author(s):  
Vladislav Zdravković ◽  
Tanja Palija ◽  
Aleksandar Lovrić ◽  
Anđela Obradović
Keyword(s):  
Multivariate Analysis ◽  
Bond Strength ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Medium Density ◽  
Substrate Type ◽  
Bond Quality ◽  
The Impact ◽  
Moisture Resistant

The choice of optimal pressing regime for certain types of substrate is of great importance in production of veneered panels. In this paper, the impact of pressing regime on the bonding strength of beech and oak veneers, glued with urea-formaldehyde (UF) adhesive, on medium-density fiberboard (MDF), and moisture-resistant MDF (MR MDF) substrates was examined. The analyses showed a generally higher bond strength with oak veneer compared to beech veneer, which was also the case with regular MDF compared to moisture-resistant MDF. Multivariate analysis of variance (ANOVA) showed that with beech veneer, all of the used regimes produced better results on regular MDF compared to moisture-resistant MDF. In contrast, with oak veneer, the influence of pressing regime had a more noteworthy impact than the type of substrate used. These results indicated that the use of MR MDF as substrate in combination with UF adhesive was inadequate.

scholarly journals Investigation of the Impact of Graphene Nanoplatelets (GnP) on the Bond Stress of High-Performance Concrete Using Pullout Testing

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7054
Author(s):  
Fouad Ismail Ismail ◽  
Yassir M. Abbas ◽  
Nasir Shafiq ◽  
Galal Fares ◽  
Montasir Osman ◽  
...  
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
Prediction Models ◽  
High Performance Concrete ◽  
Control Sample ◽  
Design Procedure ◽  
Graphene Nanoplatelets ◽  
Steel Reinforcement ◽  
Bond Stress ◽  
The Impact

Efficient load transmission between concrete and steel reinforcement by bonding action is a key factor in the process of the design procedure of bar-reinforced concrete structures. To enhance the bond strength of steel/concrete composites, the impact of graphene nanoplatelets (GnP) on the bond stress and bond stress–slip response of deformed reinforcement bars, embedded in high-performance concrete (HPC), was investigated using bar pullout tests. In the current study, 36 samples were produced and examined. The main variables were the percentages of GnP, the steel reinforcement bar diameter, and embedded length. Bond behavior, failure mode, and bond stress-slip response were studied. Based on the experimental findings, the inclusion of GnP had a significant favorable influence on the bar-matrix interactions due to the bridging action of GnP as a nano reinforcement. For 0.02 wt.% of GnP, the bond strength was enhanced by more than 41.28% and 53.90% for steel bar diameters of 10 and 16 mm, respectively. The HPC-GnP mixture displayed a reduction in the initial slippage in comparison to the control sample. The test findings were compared to the prediction models created by other researchers and the ACI 408R-12 code.

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