• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.9-16
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• 2012

In this study, the effect of metakaoline and silica fume on the bond performances of structural polyvinyl alcohol (PVA) fiber in cement mortar, including bond strength, interface toughness, and microstructure analysis are presented. Metakaoline and silica fume contents ranging from 0 % to 15 % are used in the mix proportions. Pullout tests are conducted to measure the bond performance of PVA fiber from cement mortar. Test results showed the incorporation of metakaoline and silica fume can effectively enhance the PVA fiber-cement mortar interfacial properties. Bond strength and interface toughness increased with metakaoline and silica fume content up to 10 % in cement mortar and decreased when the metakaoline and silica fume content reached 15 %. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results.

• Advances in concrete construction
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• v.7 no.3
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• pp.191-201
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• 2019

Bamboo concrete bond behaviour is investigated through pullout test in this work. The bamboo strip to be used as reinforcement inside concrete is first treated with chemical adhesive to make the bamboo surface impermeable. Various surface coatings are explored to understand their water repellant properties. The chemical action at the bamboo concrete interface is studied through different chemical coatings, sand blasting, and steel wire wrapping treatment. Whereas mechanical action at the bamboo concrete interface is studied by developing mechanical interlock. The result of pullout tests revealed a unique combination of surface treatment and grooved bamboo profile. This combination of surface treatment and a grooved bamboo profile together enhances the strength of bond. Performance of a newly developed grooved bamboo strip is verified against equivalent plain rectangular bamboo strip. The test results show that the proposed grooved bamboo reinforcement, when treated, shows highest bond strength compared to treated plain, untreated plain and untreated grooved bamboo reinforcement. Also, it is observed that bond strength is majorly influenced by the type of surface treatment, size and spacing of groove. The changes in bamboo-concrete bond behavior are observed during the experimentation.

• Journal of the Korean Chemical Society
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• v.68 no.2
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• pp.65-73
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• 2024

The halide-acetylene anions, X^--HCCH (X = F, Cl, and Br) have been studied by using several different ab initio and DFT methods to determine structures, hydrogen-bond energies, vibrational frequencies of the anion complexes. Although the halide-acetylene complexes all have linear equilibrium structures, it is found that the fluoride complex is characterized with distinctively different structure and interactions compared to those of the chloride and bromide complexes. The performance of various density functionals on describing ionic hydrogen-bonded complexes is assessed by examining statistical deviations with respect to high level ab initio CCSD(T) results as reference. The density functionals employed in the present work show considerably varying degrees of performance depending on the properties computed. The performances of each density functional on geometrical parameters related with the hydrogen bond, hydrogen-bond energies, and scaled harmonic frequencies of the anion complexes are examined and discussed based on the statistical deviations.

• Advances in concrete construction
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• v.13 no.3
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• pp.265-279
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• 2022

The roughness of substrate concrete interfaces before new concrete placement has a major effect on the interface bond behaviour. However, there are challenges associated with the consistency of the final roughness interface prepared using conventional roughness preparation methods which influences the interface bond performance. In this study, five quantitative interface roughness textures with different roughness tooth angles, depths, and tooth distribution were created to ensure consistency of interface roughness and to evaluate the bond behaviour at a precast and new concrete interface using the splitting tensile test, slant shear test, and double-shear test. In addition, smooth interface specimens and two separate the pitting interface roughness were also utilized. Obtained results indicate that the quantitative roughness has a very limited effect on the interface tensile bond strength if no extra micro-roughness or bonding agent is added at the interface. The roughness method however causes enhanced shear bond strength at the interface. Increased tooth depth improved both the tensile and shear bond strength of the interfaces, while the tooth distribution mainly influenced the shear bond strength. Major failure modes of the test specimens include interface failure, splitting cracks, and sliding failure, and are influenced by the tooth depth and tooth distribution. Furthermore, the interface properties were obtained and presented while a comparison between the different testing methods, in terms of bond strength, was performed.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.599-611
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• 2022

Tendon reinforced cemented soil is applied extensively in foundation stabilisation and improvement, especially in areas with soft clay. To solve the deterioration problem led by steel corrosion, the glass fiber-reinforced polymer (GFRP) tendon is introduced to substitute the traditional steel tendon. The interface bond strength between the cemented soil matrix and GFRP tendon demonstrates the outstanding mechanical property of this composite. However, the lack of research between the influence factors and bond strength hinders the application. To evaluate these factors, back propagation neural network (BPNN) is applied to predict the relationship between them and bond strength. Since adjusting BPNN parameters is time-consuming and laborious, the particle swarm optimisation (PSO) algorithm is proposed. This study evaluated the influence of water content, cement content, curing time, and slip distance on the bond performance of GFRP tendon-reinforced cemented soils (GTRCS). The results showed that the ultimate and residual bond strengths were both in positive proportion to cement content and negative to water content. The sample cured for 28 days with 30% water content and 50% cement content had the largest ultimate strength (3879.40 kPa). The PSO-BPNN model was tuned with 3 neurons in the input layer, 10 in the hidden layer, and 1 in the output layer. It showed outstanding performance on a large database comprising 405 testing results. Its higher correlation coefficient (0.908) and lower root-mean-square error (239.11 kPa) were obtained compared to multiple linear regression (MLR) and logistic regression (LR). In addition, a sensitivity analysis was applied to acquire the ranking of the input variables. The results illustrated that the cement content performed the strongest influence on bond strength, followed by the water content and slip displacement.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.68-74
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• 2015

Objectives: This study examined the effects of additional acid etching on the dentin bond strength of one-step self-etch adhesives with different compositions and pH. The effect of ethanol wetting on etched dentin bond strength of self-etch adhesives was also evaluated. Materials and Methods: Forty-two human permanent molars were classified into 21 groups according to the adhesive types (Clearfil SE Bond [SE, control]; G-aenial Bond [GB]; Xeno V [XV]; Beauti Bond [BB]; Adper Easy Bond [AE]; Single Bond Universal [SU]; All Bond Universal [AU]), and the dentin conditioning methods. Composite resins were placed on the dentin surfaces, and the teeth were sectioned. The microtensile bond strength was measured, and the failure mode of the fractured specimens was examined. The data were analyzed statistically using two-way ANOVA and Duncan's post hoc test. Results: In GB, XV and SE ($pH{\leq}2$), the bond strength was decreased significantly when the dentin was etched (p < 0.05). In BB, AE and SU (pH 2.4 - 2.7), additional etching did not affect the bond strength (p > 0.05). In AU (pH = 3.2), additional etching increased the bond strength significantly (p < 0.05). When adhesives were applied to the acid etched dentin with ethanol-wet bonding, the bond strength was significantly higher than that of the no ethanol-wet bonding groups, and the incidence of cohesive failure was increased. Conclusions: The effect of additional acid etching on the dentin bond strength was influenced by the pH of one-step self-etch adhesives. Ethanol wetting on etched dentin could create a stronger bonding performance of one-step self-etch adhesives for acid etched dentin.

• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.643-660
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• 2013

Reinforced concrete structures are vulnerable to high temperature conditions such as those during a fire. At elevated temperatures, the mechanical properties of concrete and reinforcing steel as well as the bond between steel rebar and concrete may significantly deteriorate. The changes in the bonding behavior may influence the flexibility or the moment capacity of the reinforced concrete structures. The bond strength degradation is required for structural design of fire safety and structural repair after fire. However, the investigation of bonding between rebar and concrete at elevated temperatures is quite difficult in practice. In this study, bond constitutive relationships are developed for normal and high-strength concrete (NSC and HSC) subjected to fire, with the intention of providing efficient modeling and to specify the fire-performance criteria for concrete structures exposed to fire. They are developed for the following purposes at high temperatures: normal and high compressive strength with different type of aggregates, bond strength with different types of embedment length and cooling regimes, bond strength versus to compressive strength with different types of embedment length, and bond stress-slip curve. The proposed relationships at elevated temperature are compared with experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.93-94
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• 2009

In this paper, the bond performance between prestressing strand and Ultra High Performance Concrete members are verified to collect the basis data of UHPC increased in practical uses recently. Concrete pouring direction, strand location and strand size were the main parameters of UHPC. As a result, the initial bond performances are influenced by all above parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.129-133
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• 1995

The purpose of this study is to evaluate the flexural bond performance in beam using 3-types anti-corrosion coatings. For the test. we used $15\times\times20\times110cm$ R.C beams, in which the epoxy, the red lead, and the cementitious anti-corrosion coating re-bars used. The results of test using these 3-type anti-corrosion coatings are shown that the flexural bond performance of cementitious anti-corrosion coating rebar in R.C beam is superior to other anti-corrosion coatings rebars.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.265-271
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• 1997

A bond graph modeling approach which is equivalent to a finite element method is formulated in the case of the piezoelectric thickness vibrator. This formulation suggests a new definition of the generalized displacements for a continuous system as well as the piezoelectric thickness vibrator. The newly defined coordinates are illustrated to be easily interpreted physically and easily used in analysis of the system performance. Compared to the Mason equivalent circuit model, the bond graph model offers the primary advantage of physical realizability. Compared to circuit models based on standard discrete electrical elements, the main advantage of the bond graph model is a greater physical accuracy because of the use of multiport energic elements. While results are presented here for the thickness vibrator, the modeling method presented is general in scope and can be applied to arbitrary physical systems.