scholarly journals Influence of Nano-silica and Polypropylene Fibers on Bond Strength of Reinforcement and Structural Lightweight Concrete

2013 ◽  
Vol 27 (2 (B)) ◽  
Author(s):  
S. H. Hashemi
Keyword(s):  
Bond Strength ◽  
Lightweight Concrete ◽  
Polypropylene Fibers ◽  
Nano Silica

scholarly journals Hybrid artificial intelligence-based bond strength model of CFRP-lightweight concrete composite

2018 ◽  
Vol 192 ◽  
pp. 02018
Author(s):  
Emmanuel Macabenta Lazo ◽  
John Pepard Mendoza Rinchon
Keyword(s):  
Bond Strength ◽  
Lightweight Concrete ◽  
Influential Factors ◽  
Strength Model ◽  
Bond Performance ◽  
High Bond ◽  
Artificial Neural Network Ann ◽  
Hybrid Artificial Intelligence ◽  
The Relationship ◽  
Influential Parameters

Different retrofitting techniques are commonly used to sustain the design life of heavy damage and deteriorated concrete structures, whilst epoxy-bonded carbon fiber reinforced polymer (CFRP) has emerged as a widely known retrofitting method. Consequently, a sound understanding of the bond strength between structural lightweight concrete (LWC) and CFRP based on influential factors is essential in safety and economic requirements. In this study, a hybrid bond strength model using the artificial neural network (ANN) and genetic algorithm (GA) was developed to furtherly understand the bond of a CFRP strengthened LWC structure. ANN was able to establish under satisfactory performance the relationship between the maximum bond load and the following influential parameters: width of CFRP (bfrp), total CFRP bond length (Lfrp), CFRP thickness (tfrp), and CFRP angle of orientation (θfrp). Furthermore, GA was able to derive the optimal configuration of the influential parameters resulted in high bond performance. Moreover, the optimization results also validated the sensitivity of each parameter on the interfacial bond behavior between LWC and CFRP.

Assessment of mechanical strength of nano silica concrete (NSC) subjected to elevated temperatures

2019 ◽  
Vol 10 (1) ◽  
pp. 90-109 ◽  
Author(s):  
Hala Mohamed Elkady ◽  
Ahmed M. Yasien ◽  
Mohamed S. Elfeky ◽  
Mohamed E. Serag
Keyword(s):  
Elevated Temperature ◽  
Bond Strength ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Mechanical Tests ◽  
Nano Silica ◽  
Content Type ◽  
Post Exposure ◽  
Concrete Mix ◽  
Bond Strengths

Purpose This paper aims to inspect the effect of indirect elevated temperature on the mechanical performance of nano silica concrete (NSC). The effect on both compressive and bond strengths is studied. Pre- and post-exposure to elevated temperature ranges of 200 to 600°C is examined. A range covered by three percentages of 1.5, 3 and 4.5 per cent nano silica (NS) in concrete mixes is tested. Design/methodology/approach Pre-exposure mechanical tests (normal conditions – room temperature), using 3 per cent NS in the concrete mix, led to the highest increase in both compressive and bond strengths (43 per cent and 38.5 per cent, respectively), compared to the control mix without NS (based on 28-day results). It is worth noticing that adding NS to the concrete mixes does not have a significant effect on improving early-age strength. Besides, permeability tests are performed on NSC with different NS ratios. NS improved the concrete permeability for all tested percentages of NS. The maximum reduction is accompanied by the maximum percentage used (4.5 per cent NS in the NSC mix), reducing permeability to half the value of the concrete mix without NS. As for post-exposure to elevated-temperature mechanical tests, NSC with 1.5 per cent NS exhibited the lowest loss in strength owing to indirect heat exposure of 600°C; the residual compressive and bond strengths are 73 per cent and 35 per cent, respectively. Findings The dispersion technique of NS has a key role in NSC-distinguished mechanical performance with NSC having lower NS percentages. NS significantly improved bond strength. NS has a remarkable effect on elevated temperature endurance. The bond strength of NSC exposed to elevated temperatures suffered faster deterioration than compressive strength of the exposed NSC. Research limitations/implications A special scale factor needs to be investigated for the NSC. Originality/value Although a lot of effort is placed in evaluating the benefits of using nano materials in structural concrete, this paper presents one of the first outcomes of the thermal effects on concrete mixes with NS as a partial cement replacement.

Effect Bonding Strength Steel Reinforcement with Epoxy Coating on the Character Destruction of Autoclaved Aerated Concrete Beams in Bending

2019 ◽  
Vol 974 ◽  
pp. 665-671
Author(s):  
Omar Ismael Alhashimi ◽  
AL-Hasnawi Yasser Sami Ghareb
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Shear Failure ◽  
Lightweight Concrete ◽  
Construction Material ◽  
Reinforced Concrete Beam ◽  
Reinforcing Steel ◽  
Deep Beams ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete

Many of the complex reinforced Autoclaved Aerated Concrete characteristics under shear and flexure are yet to be identified to employ this material advantageously and economically, as it has many advantages of low weight, fire resistance, acoustic and thermal insulation. It is observed in the article that under two-points loading system, diagonal cracks are usually the first cracks to be observed in the deep beam clear span. The diagonal cracks first are developed in relatively deep beams and the flexural cracks are first developed in shallower beam. The principal mode of failure in the deep beams having adequate reinforcement is diagonal tension cracking. The shear failure is a common type for all beams. This indicates a weak the bond strength between lightweight concrete and reinforcing steel. There are many factors affecting the bond strength between the lightweight concrete and reinforcing steel, where the compressive strength plays an important role in bond strength, and the bond strength is increased by increasing the compressive strength. The AAC beams have the potential to be an excellently energy-saving construction material and is believed to emerge as an alternative to traditional reinforced concrete beam in the near future. This is proved by the experimental analysis.

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