pullout test
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2022 ◽  
Author(s):  
Yiqun Wang ◽  
Yu Li ◽  
Liang Han ◽  
Jun Wang ◽  
Cong Zhang ◽  
...  

Abstract Purpose We built a loosening model based on the original infection model of rabbit and evaluated the performance characteristics of 18F-FDG and 68Ga-FAPI in infection and loosening. Methods After surgery, the rabbits were divided into four groups, six in the control group and 10 in the loosening, S. aureus and S. epidermis groups. PET/CT and serological examination were performed every two weeks for three times. After sacrificed, micro-CT, tissue culture, pullout test and scanning electron microscope were performed. Results As for 18F-FDG, performances of control and loosening groups were similar. SUVmax of S. aureus had been consistently in the high range than that of S. epidermis. As for 68Ga-FAPI, control group had the lowest SUVmax in the second week and increased gradually. SUVmax of loosening group began exceed control group since the second week. SUVmax of S. aureus in the second week was the lowest among four group and raised as the number of weeks increased and equalled to SUVmax of S. epidermis in the sixth week. Linear regressions between SUVmax and serology showed that 18F-FDG was positively correlated with CRP and IL-6 while 68Ga-FAPI revealed negative and positive correlation with CRP and IL-6 in the second and sixth week. Besides, both SUVmax and MTV of 18F-FDG or 68Ga-FAPI were negatively correlated with BV/TV and BS/TV. Conclusion In this longitudinal observation, 68Ga-FAPI showed greater sensitivity than 18F-FDG in detecting diseases, and 68Ga-FAPI had not intestinal and muscular uptake. MTV of 68Ga-FAPI were larger than 18F-FDG, which meant that 68Ga-FAPI had the potential to define the scope of lesions more accurately. Finally, SUVmax could not differentiate loosening and infection in 68Ga-FAPI, further study about diagnostic criteria was warranted.


2021 ◽  
Author(s):  
Xiangyan Wu ◽  
Xiangling Chen ◽  
Jianping Yang ◽  
Xin Hu ◽  
Guang Yang

Double layer fine-surfacing technology is a thin layer maintenance technology of pavement positive texture, which plays an important role in preventing road safety accidents. Bonding performance is the key quality control index of the double layer fine-surfacing, which directly affects its service performance and durability. In this paper, the bonding mechanism of the double layer fine-surfacing is analyzed, and the bonding strength between the double layer fine-surfacing and the old asphalt pavement surface is studied by using the pullout test method under the factors of different cement dosage and different temperature environment, and the bonding index of the double layer fine-surfacing is put forward. Experiments show that the double layer fine-surfacing technology has the characteristics of super bonding and wear resistance. It is an economical and practical maintenance technology and has broad development prospects.


2021 ◽  
Vol 11 (19) ◽  
pp. 9147
Author(s):  
Marcin Ćwirko ◽  
Małgorzata Jastrzębska

This study considered the possibility of using steel gabion baskets made of welded mesh for a soil-strengthening function. Examples of such applications are known for meshes made of wires with diameters from 6.3 to 12.7 mm and mesh openings from 125 to 225 mm. In the case of a welded grid, the pulling resistance of fine-grained soil consists of two factors: frictional resistance and bearing resistance. Therefore, for the purposes of this issue, a simplified laboratory pullout test was carried out with four types of welded steel grid (common in Europe) embedded in the fine sand. The geometry of the grid (opening size: 76.2 × 76.2 mm), the type of steel (low carbon steel, tensile strength from 500 to 700 MPa), the diameter of the wire (2.7–4.5 mm) and its cover (ZN + PVC or ZnAl) were taken into account during the analysis. It was unequivocally stated that as the stiffness of the steel grid itself increases, its strength increases during the pullout test, which is not so obvious in the case of popular steel woven meshes. In addition, it has been shown that steel welded meshes with wire diameters less than 6 mm are suitable for soil reinforcement in structures with gabion facing, and the determined apparent friction coefficient (μk = 0.39–1.47) takes values similar to the friction coefficient given in references for welded meshes of larger diameters. This is a positive premise for starting further research on the use of wires of smaller diameters for welded mesh production used as soil reinforcement.


Author(s):  
Dongyoung Choi ◽  
◽  
Sohyeon Heo ◽  
Yeongseok Jeong ◽  
Minho Kwon

2021 ◽  
Author(s):  
Zahir Aldulaymi

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.


2021 ◽  
Author(s):  
Zahir Aldulaymi

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.


2021 ◽  
Vol 23 (1) ◽  
pp. 37-45
Author(s):  
Amirul Huda ◽  
Henry Apriyatno

Abstract: The use of anchors in construction is gaining popularity to connect steel and concrete constructions, and to transmit tensile loads acting onto the concrete. This research aims to find out the difference in the strength of anchor based on two methods of installations that are cast in place compared to post installed with the influence of effective depth, diameter of anchor and quality of concrete, and failure of concrete breakout. Expansion anchor used in this study is "Sanko" M12x100 and ready-mix concrete PT Bonindo Ungaran, fc 25 MPa with 6 pieces of test specimens of 300x300x150 mm. Each specimen has 4 anchors with a distance between the anchors of 100 cm, the distance between the anchors to the edge of the concrete 100 mm, and the depth of installation (hef) of 60 mm. The result of the study is the predicted value of the anchor pullout capacity with the failure of concrete breakout due to the theoretical pullout, namely 42,223 N, anchor pullout test results with cast in place method of 40,574 N and post installed method by 37,494 N. Tensile strength tests (material) of anchor (fy) 338 MPa, for flat concrete compressive strength strength of (f’c) 25,698 MPa. The results of the cast in place pullout test are larger and better than post installed (40574 N>37494 N). Failure that occurred in cast in place method is a failure of concrete breakout and post installed method has occurred slip. Failures that occur are relevant to the theory.


Author(s):  
Anis Rosyidah ◽  
J. Adhijoso Tjondro ◽  
I Ketut Sucita
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