Innegra fibers, which are based on Olefin material, provide very good mechanical properties if woven into a composite structure. These fibers are relatively new, and the composites made of them have been less investigated than fibers such as glass and carbon. In this research, the mechanical properties of Innegra composite specimens, which are manufactured by the vacuum injection process, are investigated experimentally. The experimental results are compared with the results of a micromechanical model, and a good matching is observed. Also, the behavior of these composites under low-velocity impact is experimentally and numerically evaluated. This evaluation includes various parameters such as maximum displacement, maximum force, absorbed energy, and return velocity. The influences of the number of layers and the shape of the impactor are also studied. The results show good agreement between the numerical analyses and the experimental tests.
{"title":"Experimental and Numerical Study of Low-Velocity Impact Behavior of Woven Innegra Fiber Composite Plates","authors":"Mohamad Fuladvand, Sayyed Roohollah Kazemi","doi":"10.1520/jte20230660","DOIUrl":"https://doi.org/10.1520/jte20230660","url":null,"abstract":"\u0000 Innegra fibers, which are based on Olefin material, provide very good mechanical properties if woven into a composite structure. These fibers are relatively new, and the composites made of them have been less investigated than fibers such as glass and carbon. In this research, the mechanical properties of Innegra composite specimens, which are manufactured by the vacuum injection process, are investigated experimentally. The experimental results are compared with the results of a micromechanical model, and a good matching is observed. Also, the behavior of these composites under low-velocity impact is experimentally and numerically evaluated. This evaluation includes various parameters such as maximum displacement, maximum force, absorbed energy, and return velocity. The influences of the number of layers and the shape of the impactor are also studied. The results show good agreement between the numerical analyses and the experimental tests.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141703598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Ai, L. K C, Elhussien Elbatanouny, Alexander Henderson, P. Ziehl
Bridges deteriorate over time because of factors like rebar corrosion and concrete damage, reducing their load-bearing capacity. Traditional load grading processes are costly and time-consuming, often resulting in traffic disruptions of one to four days because of lane closures. This study introduced a load rating technique leveraging digital twins technology. Data related to crack evolution and inherent strain during loading were obtained by monitoring the laboratory bridge slabs using potentiometers, strain gauges, and fiber optic sensors. Subsequently, a calibrated three-dimensional finite element model, representing different loading scenarios, was crafted, forming the foundation for the digital twins model of bridge slabs. The slab model was then integrated into a bridge span, constituting a digital twins model of the bridge span for load rating tests. The developed digital twins model was applied to a bridge in Abbeville, South Carolina, and its accuracy was validated with field monitoring data.
{"title":"Assisting Load Rating Testing of Precast Reinforced Concrete Bridge Slab through Digital Twins and Field Monitoring Data","authors":"Li Ai, L. K C, Elhussien Elbatanouny, Alexander Henderson, P. Ziehl","doi":"10.1520/jte20230748","DOIUrl":"https://doi.org/10.1520/jte20230748","url":null,"abstract":"\u0000 Bridges deteriorate over time because of factors like rebar corrosion and concrete damage, reducing their load-bearing capacity. Traditional load grading processes are costly and time-consuming, often resulting in traffic disruptions of one to four days because of lane closures. This study introduced a load rating technique leveraging digital twins technology. Data related to crack evolution and inherent strain during loading were obtained by monitoring the laboratory bridge slabs using potentiometers, strain gauges, and fiber optic sensors. Subsequently, a calibrated three-dimensional finite element model, representing different loading scenarios, was crafted, forming the foundation for the digital twins model of bridge slabs. The slab model was then integrated into a bridge span, constituting a digital twins model of the bridge span for load rating tests. The developed digital twins model was applied to a bridge in Abbeville, South Carolina, and its accuracy was validated with field monitoring data.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141697215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The impact-echo method is widely used to detect grouting defects within prestressed concrete tendon ducts. However, when the distance from the rebar to the test surface was half the depth from the defect to the test surface, the amplitude spectrum of the conventional fast Fourier transform failed to distinguish between internal defects in tendon ducts and external rebar. To overcome this challenge, in this paper, the phase spectrum and amplitude spectrum were combined to identify the internal defects and external rebar of the tendon ducts. First, the amplitude spectrum was used to determine the depth of defects and rebar, and then the phase spectrum was used to further determine the category of the reflected interface (defect interface or rebar interface). The feasibility of the method was verified by model tests and numerical simulations. Afterward, the effects of impact duration, sampling time, the size of defect, duct thickness, rebar, and defect burial depth on the phase of the impact echo were analyzed. The results show that the proposed method can identify the internal defects in the tendon ducts and rebars very well.
{"title":"Application of the Phase Spectrum of Impact Echo in the Detection of Grouting Defects in the Tendon Ducts","authors":"Wenhao Chai, Yaxun Yang","doi":"10.1520/jte20230532","DOIUrl":"https://doi.org/10.1520/jte20230532","url":null,"abstract":"\u0000 The impact-echo method is widely used to detect grouting defects within prestressed concrete tendon ducts. However, when the distance from the rebar to the test surface was half the depth from the defect to the test surface, the amplitude spectrum of the conventional fast Fourier transform failed to distinguish between internal defects in tendon ducts and external rebar. To overcome this challenge, in this paper, the phase spectrum and amplitude spectrum were combined to identify the internal defects and external rebar of the tendon ducts. First, the amplitude spectrum was used to determine the depth of defects and rebar, and then the phase spectrum was used to further determine the category of the reflected interface (defect interface or rebar interface). The feasibility of the method was verified by model tests and numerical simulations. Afterward, the effects of impact duration, sampling time, the size of defect, duct thickness, rebar, and defect burial depth on the phase of the impact echo were analyzed. The results show that the proposed method can identify the internal defects in the tendon ducts and rebars very well.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141709717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To investigate the eccentric compression performance of cold-formed thin-walled steel-reconstituted bamboo (CTS-RB) composite columns, 14 specimens were tested under eccentric compression conditions. The parameters included section steel type, thickness of reconstituted bamboo (RB) plates, slenderness ratio, and eccentricity. The study analyzed the observed damage modes and eccentric compression performance of the specimens and investigated the bearing capacity and deformation capacity. It was indicated that the composite of RB and cold-formed thin-walled steel (CTS), connected by self-tapping screws and structural adhesive to form an integrated column, has produced acceptable results. The bearing capacity of the test specimen is influenced significantly by the eccentricity. On this basis, a finite element model is created that considers nonlinearities in material, geometry, and contact. The finite element calculations show good agreement with experimental results, with an error rate within 17 %, which validates the feasibility of using finite element methods. Moreover, the paper thoroughly examines the effects of slenderness ratio and eccentricity on the load carrying capacity of the composite column. This study presents the data fitting of the eccentricity coefficient and the slenderness ratio coefficient in the formulas of the yield and bending capacity of the composite columns, and the obtained theoretical calculations have an error of less than 16 % with the experiment, which is applicable to the prediction of the load bearing capacity of the composite columns.
{"title":"Eccentric Compression Performance of Cold-Formed Thin-Walled Steel-Reconstituted Bamboo Composite Columns","authors":"X. Zhang, Qiaoling Zhang, Ziyan Zeng","doi":"10.1520/jte20230751","DOIUrl":"https://doi.org/10.1520/jte20230751","url":null,"abstract":"\u0000 To investigate the eccentric compression performance of cold-formed thin-walled steel-reconstituted bamboo (CTS-RB) composite columns, 14 specimens were tested under eccentric compression conditions. The parameters included section steel type, thickness of reconstituted bamboo (RB) plates, slenderness ratio, and eccentricity. The study analyzed the observed damage modes and eccentric compression performance of the specimens and investigated the bearing capacity and deformation capacity. It was indicated that the composite of RB and cold-formed thin-walled steel (CTS), connected by self-tapping screws and structural adhesive to form an integrated column, has produced acceptable results. The bearing capacity of the test specimen is influenced significantly by the eccentricity. On this basis, a finite element model is created that considers nonlinearities in material, geometry, and contact. The finite element calculations show good agreement with experimental results, with an error rate within 17 %, which validates the feasibility of using finite element methods. Moreover, the paper thoroughly examines the effects of slenderness ratio and eccentricity on the load carrying capacity of the composite column. This study presents the data fitting of the eccentricity coefficient and the slenderness ratio coefficient in the formulas of the yield and bending capacity of the composite columns, and the obtained theoretical calculations have an error of less than 16 % with the experiment, which is applicable to the prediction of the load bearing capacity of the composite columns.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141839756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crack tip constraint is a significant issue in engineering components’ design and repair decisions. The main reason is that fracture assessment procedures, such as BS 7910, rely on lower-bound fracture toughness test data from deeply cracked bend specimens. This can generate stress states under various loading conditions with an appropriate crack tip stress triaxiality for metallic structures. Many real components (e.g., oil and gas pipelines) have small in-plane (shallow cracks) and out-of-plane (thin-wall thickness) dimensions that can cause a reduction in crack tip constraint to a considerable amount, thereby increasing the fracture toughness. As such, the structural assessment of low-constraint structural components using fracture toughness data obtained from deeply notched specimens may be safe but overly conservative, resulting in unnecessary repair shutdowns and costs. Consequently, relating fracture toughness values determined from laboratory specimens to real structural components becomes an issue in structural integrity assessments based on the two-parameter fracture mechanics methodology. This study investigates the applicability of the constraint-based failure assessment diagram (FAD) approach for the evaluation of cracked pin-loaded single-edge notched tension and three-point single-edge notched bend specimens at low (−120°C) and room temperatures. The analyses reveal that the experimentally measured toughness values, J0, depend on the crack sizes for the considered specimen geometries (a/W = 0.1, 0.3, 0.5). The results show the benefits of using constraint-modified FAD approach for the assessment of shallow cracks. Therefore, the enhanced toughness associated with constraint reduction indicated an increased margin and allows realistic design and repair decision-making that can help prevent catastrophic failures.
{"title":"Experimental Investigation of Crack Tip Constraint Effects on Fracture Assessment of API 5L X65 Steel Grade for Low-Temperature Applications (−120°C)","authors":"Paul Sukpe, R. Vignjevic, Kevin Hughes, R. Kulka","doi":"10.1520/jte20230747","DOIUrl":"https://doi.org/10.1520/jte20230747","url":null,"abstract":"\u0000 Crack tip constraint is a significant issue in engineering components’ design and repair decisions. The main reason is that fracture assessment procedures, such as BS 7910, rely on lower-bound fracture toughness test data from deeply cracked bend specimens. This can generate stress states under various loading conditions with an appropriate crack tip stress triaxiality for metallic structures. Many real components (e.g., oil and gas pipelines) have small in-plane (shallow cracks) and out-of-plane (thin-wall thickness) dimensions that can cause a reduction in crack tip constraint to a considerable amount, thereby increasing the fracture toughness. As such, the structural assessment of low-constraint structural components using fracture toughness data obtained from deeply notched specimens may be safe but overly conservative, resulting in unnecessary repair shutdowns and costs. Consequently, relating fracture toughness values determined from laboratory specimens to real structural components becomes an issue in structural integrity assessments based on the two-parameter fracture mechanics methodology. This study investigates the applicability of the constraint-based failure assessment diagram (FAD) approach for the evaluation of cracked pin-loaded single-edge notched tension and three-point single-edge notched bend specimens at low (−120°C) and room temperatures. The analyses reveal that the experimentally measured toughness values, J0, depend on the crack sizes for the considered specimen geometries (a/W = 0.1, 0.3, 0.5). The results show the benefits of using constraint-modified FAD approach for the assessment of shallow cracks. Therefore, the enhanced toughness associated with constraint reduction indicated an increased margin and allows realistic design and repair decision-making that can help prevent catastrophic failures.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141695845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the impact of styrenic triblock copolymer (STC) modifiers with different block ratios, polymerization methods, and soft segment structures on the microstructure and rheological properties of modified asphalt. Six commonly used STCs were selected, and modified asphalt was prepared using a rapid quenching method without stabilizers, ensuring no phase separation. These samples underwent laser confocal microscopy, temperature sweep, multiple stress creep recovery, linear amplitude sweep, and bending beam rheometer tests. The findings are as follows: Based on the characteristics of different STC types, it is observed that modifiers with higher block ratios and crystallinity are more challenging to disperse uniformly in modified asphalt. However, the presence of methyl side chains enhances the dispersion uniformity of the modifier in asphalt. Additionally, star-shaped modifiers exhibit weaker dispersion uniformity compared to linear ones. Among them, the styrene-butadiene-styrene (SBS) modified asphalt with a block ratio of 3/7 demonstrates the highest composite modulus and maximum creep recovery, showcasing superior high-temperature performance. Star-shaped SBS-modified asphalt excels in high-temperature performance and exhibits better stress relaxation at low temperatures, but it has a lower fatigue life compared to linear SBS. Styrene-ethylene-butadiene-styrene modified asphalt exhibits the maximum modulus but the poorest elastic recovery performance. Styrene-isoprene-styrene modified asphalt has the minimum modulus and fatigue life but demonstrates optimal elastic recovery.
本研究探讨了不同嵌段比、聚合方法和软段结构的苯乙烯三嵌段共聚物（STC）改性剂对改性沥青微观结构和流变特性的影响。我们选择了六种常用的 STC，并采用不含稳定剂的快速淬火法制备改性沥青，以确保不发生相分离。对这些样品进行了激光共聚焦显微镜、温度扫描、多应力蠕变恢复、线性振幅扫描和弯曲梁流变仪测试。研究结果如下：根据不同 STC 类型的特点，可以发现嵌段比和结晶度较高的改性剂更难均匀分散在改性沥青中。然而，甲基侧链的存在会提高改性剂在沥青中的分散均匀性。此外，与线性改性剂相比，星形改性剂的分散均匀性较弱。其中，嵌段比为 3/7 的苯乙烯-丁二烯-苯乙烯（SBS）改性沥青具有最高的复合模量和最大的蠕变恢复能力，显示出卓越的高温性能。星形 SBS 改性沥青的高温性能优异，低温应力松弛性更好，但与线形 SBS 相比，疲劳寿命较低。苯乙烯-乙烯-丁二烯-苯乙烯改性沥青的模量最大，但弹性恢复性能最差。苯乙烯-异戊二烯-苯乙烯改性沥青的模量和疲劳寿命最小，但弹性恢复性能最佳。
{"title":"Impact of Block Ratio, Polymer Architecture, and Soft Segment Structure on Modified Asphalt Rheological Performance","authors":"Hang Xiao, Dan Cao, Na Fu, Hongyu Yi","doi":"10.1520/jte20230661","DOIUrl":"https://doi.org/10.1520/jte20230661","url":null,"abstract":"\u0000 This study investigates the impact of styrenic triblock copolymer (STC) modifiers with different block ratios, polymerization methods, and soft segment structures on the microstructure and rheological properties of modified asphalt. Six commonly used STCs were selected, and modified asphalt was prepared using a rapid quenching method without stabilizers, ensuring no phase separation. These samples underwent laser confocal microscopy, temperature sweep, multiple stress creep recovery, linear amplitude sweep, and bending beam rheometer tests. The findings are as follows: Based on the characteristics of different STC types, it is observed that modifiers with higher block ratios and crystallinity are more challenging to disperse uniformly in modified asphalt. However, the presence of methyl side chains enhances the dispersion uniformity of the modifier in asphalt. Additionally, star-shaped modifiers exhibit weaker dispersion uniformity compared to linear ones. Among them, the styrene-butadiene-styrene (SBS) modified asphalt with a block ratio of 3/7 demonstrates the highest composite modulus and maximum creep recovery, showcasing superior high-temperature performance. Star-shaped SBS-modified asphalt excels in high-temperature performance and exhibits better stress relaxation at low temperatures, but it has a lower fatigue life compared to linear SBS. Styrene-ethylene-butadiene-styrene modified asphalt exhibits the maximum modulus but the poorest elastic recovery performance. Styrene-isoprene-styrene modified asphalt has the minimum modulus and fatigue life but demonstrates optimal elastic recovery.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141708243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mengyuan Ma, Mingshun Jiang, Lei Zhang, Qingmei Sui, Lei Jia
This paper presents a signal correlation–based two-sided detection method to detect delamination defects in widely used carbon fiber reinforced plastics with high accuracy and a convenient process. This method can improve the accuracy of ultrasonic testing and distinguish non-defective signals from defective signals, especially those with small amplitude, and to present the depth and size of defects by images. We combined the echo signals from both sides of ultrasonic detection at the same location to extract the weak defect signals and achieved the detection of materials with high ultrasonic attenuation. First, empirical mode decomposition filtering is performed on the ultrasonic raw signal. Then, the defect echoes are identified by smart thresholding and combined with the results of ultrasonic detection on both sides. Next, the defect depth and size are calculated, and the defect image is drawn. Finally, the ultrasonic phased array C-scan obtained by the ultrasonic phased array equipment was compared with the detection results of carbon fiber laminates with artificial delamination by the algorithm of the present invention, showing that the proposed algorithm defect depth calculation error is less than 4 %, the defect size calculation error is less than 0.5 mm, and it performs well in defect shape presentation and position calculation.
本文提出了一种基于信号相关性的双面检测方法，用于检测广泛使用的碳纤维增强塑料中的分层缺陷，该方法精度高、流程简便。该方法可以提高超声波检测的准确性，区分非缺陷信号和缺陷信号，尤其是振幅较小的信号，并通过图像呈现缺陷的深度和大小。我们结合同一位置超声检测两侧的回波信号，提取出微弱的缺陷信号，实现了对高超声衰减材料的检测。首先，对超声波原始信号进行经验模式分解滤波。然后，通过智能阈值识别缺陷回波，并与两侧超声波检测结果相结合。接着，计算缺陷深度和尺寸，绘制缺陷图像。最后，将超声相控阵设备获得的超声相控阵 C 扫描结果与本发明算法对人工分层碳纤维层压板的检测结果进行比较，结果表明，所提算法缺陷深度计算误差小于 4%，缺陷尺寸计算误差小于 0.5 毫米，在缺陷形状呈现和位置计算方面表现良好。
{"title":"Optimization of Weak Ultrasonic Defect Signal Detection of Carbon Fiber Composites Based on Double-Sided Pulse Reflection Scanning","authors":"Mengyuan Ma, Mingshun Jiang, Lei Zhang, Qingmei Sui, Lei Jia","doi":"10.1520/jte20230149","DOIUrl":"https://doi.org/10.1520/jte20230149","url":null,"abstract":"\u0000 This paper presents a signal correlation–based two-sided detection method to detect delamination defects in widely used carbon fiber reinforced plastics with high accuracy and a convenient process. This method can improve the accuracy of ultrasonic testing and distinguish non-defective signals from defective signals, especially those with small amplitude, and to present the depth and size of defects by images. We combined the echo signals from both sides of ultrasonic detection at the same location to extract the weak defect signals and achieved the detection of materials with high ultrasonic attenuation. First, empirical mode decomposition filtering is performed on the ultrasonic raw signal. Then, the defect echoes are identified by smart thresholding and combined with the results of ultrasonic detection on both sides. Next, the defect depth and size are calculated, and the defect image is drawn. Finally, the ultrasonic phased array C-scan obtained by the ultrasonic phased array equipment was compared with the detection results of carbon fiber laminates with artificial delamination by the algorithm of the present invention, showing that the proposed algorithm defect depth calculation error is less than 4 %, the defect size calculation error is less than 0.5 mm, and it performs well in defect shape presentation and position calculation.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141700583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexandre Luiz Manfro, João Victor Staub de Melo, B. Barra
This study evaluated whether use of a high-vinyl styrene-butadiene-styrene (SBS) copolymer can provide adequate phase stability to highly modified asphalt (HiMA). An asphalt binder was modified with 7.5 % high-vinyl SBS to produce HiMA. A conventional polymer-modified asphalt was produced with 4 % SBS without vinyl and, together with the base asphalt, considered as reference samples. In the first phase, samples were analyzed considering unaged and short-term aged conditions. The experimental procedure analyzed binder morphology using fluorescence microscopy and determined chemical functional groups through Fourier transform infrared spectroscopy (FTIR). Rheological behavior at intermediate temperatures was evaluated concerning dynamic shear modulus, phase angle, and linear amplitude sweep (LAS) tests at 20°C. High-temperature properties, including apparent viscosity, performance grade, aging index, and multiple stress creep and recovery (MSCR) test, were also assessed. In the second phase, unaged asphalt binders were subjected to storage stability test, and the top and bottom sections were evaluated through fluorescence microscopy, FTIR, LAS, and MSCR tests. The samples with 7.5 % high vinyl SBS exhibited enhanced fatigue tolerance in the LAS test compared to base asphalt (14.35 times higher at 15 % shear strain) and samples with 4 % SBS without vinyl (6.62 times higher at 15 % shear strain). Additionally, it displayed superior resistance to deformation accumulation at high temperatures (ε10 parameter from MSCR) compared to base asphalt (99.65 % smaller at 64°C) and samples with 4 % SBS without vinyl (93.05 % smaller at 64°C). However, the storage stability of the asphalt samples with 7.5 % high vinyl SBS was compromised due to phase separation, severely impacting the rheological performance at intermediate and high temperatures. It was concluded that the incorporation of high levels positively impacts mechanical/rheological performance, but the molecular characteristics of the high vinyl SBS are not capable of providing adequate storage stability at a content of 7.5 %.
本研究评估了使用高乙烯基苯乙烯-丁二烯-苯乙烯（SBS）共聚物能否为高改性沥青（HiMA）提供足够的相稳定性。用 7.5% 的高乙烯基 SBS 改性沥青粘结剂生产 HiMA。使用 4% 的 SBS（不含乙烯基）生产传统聚合物改性沥青，并将其与基质沥青一起作为参考样品。在第一阶段，对未老化和短期老化条件下的样品进行了分析。实验过程中使用荧光显微镜分析了粘结剂的形态，并通过傅立叶变换红外光谱（FTIR）确定了化学官能团。在 20°C 时，通过动态剪切模量、相位角和线性振幅扫描（LAS）测试评估了中间温度下的流变行为。此外，还评估了高温特性，包括表观粘度、性能等级、老化指数以及多应力蠕变和恢复（MSCR）试验。在第二阶段，对未老化的沥青胶结料进行了储存稳定性测试，并通过荧光显微镜、傅立叶变换红外光谱、LAS 和 MSCR 测试对顶部和底部切片进行了评估。与基质沥青相比，含 7.5% 高乙烯基 SBS 的样品在 LAS 试验中表现出更强的耐疲劳性（在剪切应变为 15% 时为基质沥青的 14.35 倍），而含 4% 不含乙烯基 SBS 的样品在剪切应变为 15% 时为基质沥青的 6.62 倍。此外，与基质沥青（64°C 时变形量减少 99.65%）和不含乙烯基的 4%BS 样品（64°C 时变形量减少 93.05%）相比，该沥青在高温（MSCR ε10 参数）条件下抗变形累积能力更强。然而，含有 7.5 % 高乙烯基 SBS 的沥青样品的储存稳定性因相分离而受到影响，严重影响了中温和高温下的流变性能。由此得出的结论是，高含量对机械/流变性能有积极影响，但高乙烯基 SBS 的分子特性无法在 7.5% 的含量下提供足够的储存稳定性。
{"title":"Phase Stability Evaluation of Highly Modified Asphalt with High Vinyl Content Copolymer","authors":"Alexandre Luiz Manfro, João Victor Staub de Melo, B. Barra","doi":"10.1520/jte20230407","DOIUrl":"https://doi.org/10.1520/jte20230407","url":null,"abstract":"\u0000 This study evaluated whether use of a high-vinyl styrene-butadiene-styrene (SBS) copolymer can provide adequate phase stability to highly modified asphalt (HiMA). An asphalt binder was modified with 7.5 % high-vinyl SBS to produce HiMA. A conventional polymer-modified asphalt was produced with 4 % SBS without vinyl and, together with the base asphalt, considered as reference samples. In the first phase, samples were analyzed considering unaged and short-term aged conditions. The experimental procedure analyzed binder morphology using fluorescence microscopy and determined chemical functional groups through Fourier transform infrared spectroscopy (FTIR). Rheological behavior at intermediate temperatures was evaluated concerning dynamic shear modulus, phase angle, and linear amplitude sweep (LAS) tests at 20°C. High-temperature properties, including apparent viscosity, performance grade, aging index, and multiple stress creep and recovery (MSCR) test, were also assessed. In the second phase, unaged asphalt binders were subjected to storage stability test, and the top and bottom sections were evaluated through fluorescence microscopy, FTIR, LAS, and MSCR tests. The samples with 7.5 % high vinyl SBS exhibited enhanced fatigue tolerance in the LAS test compared to base asphalt (14.35 times higher at 15 % shear strain) and samples with 4 % SBS without vinyl (6.62 times higher at 15 % shear strain). Additionally, it displayed superior resistance to deformation accumulation at high temperatures (ε10 parameter from MSCR) compared to base asphalt (99.65 % smaller at 64°C) and samples with 4 % SBS without vinyl (93.05 % smaller at 64°C). However, the storage stability of the asphalt samples with 7.5 % high vinyl SBS was compromised due to phase separation, severely impacting the rheological performance at intermediate and high temperatures. It was concluded that the incorporation of high levels positively impacts mechanical/rheological performance, but the molecular characteristics of the high vinyl SBS are not capable of providing adequate storage stability at a content of 7.5 %.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141697060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In general, the basis of any type of management decision-making system is a correct evaluation of the current situation, future prediction, and finally optimal decision-making. There are various field methods for road pavement evaluation, among which are destructive and nondestructive methods. One of the nondestructive testing methods is dynamic cone penetrometer (DCP) testing. The main objective of this study is to investigate the feasibility of using DCP to control the quality of pavement layers and estimate parameters such as California bearing ratio (CBR) and compaction ratio. For this purpose, DCP, CBR tests, and determination of density percentage have been used as parameters used to control the quality of pavement layers. The dynamic resistance meter or DCP is a device that is used to quickly measure the resistance of different pavement layers. This device causes a small destruction on the surface. Hence, it is also called nondestructive testing. However, to use DCP, it is necessary to measure its results with the results of prevalent and widely used tests such as CBR and to examine their relationships. In this research, the DCP, CBR, density, sieve analysis, moisture content, and Atterberg limit tests were performed on two locations (a highway under construction and a landscaping project). Then, the results of the DCP test with CBR and soil compaction ratio (R) in two different locations were investigated and the relationships between these parameters were determined. The results showed that there is a good relationship statistically between DCP and CBR parameters in both locations. Also, for the first time, a very good correlation between the R parameter and the results of the dynamic penetrometer cone test was obtained. The observations represented that the correlation coefficients are higher than 0.9 in the highway location, which had well-graded soil in comparison with the landscaping project.
{"title":"Presenting a CBR Estimation Model and Compaction Characteristics of Base Layer of Pavement Using a Dynamic Cone Penetrometer (DCP) Test","authors":"Mohammad Reza Elyasi, D. Daryaee, Fatemeh Sarabi","doi":"10.1520/jte20230157","DOIUrl":"https://doi.org/10.1520/jte20230157","url":null,"abstract":"\u0000 In general, the basis of any type of management decision-making system is a correct evaluation of the current situation, future prediction, and finally optimal decision-making. There are various field methods for road pavement evaluation, among which are destructive and nondestructive methods. One of the nondestructive testing methods is dynamic cone penetrometer (DCP) testing. The main objective of this study is to investigate the feasibility of using DCP to control the quality of pavement layers and estimate parameters such as California bearing ratio (CBR) and compaction ratio. For this purpose, DCP, CBR tests, and determination of density percentage have been used as parameters used to control the quality of pavement layers. The dynamic resistance meter or DCP is a device that is used to quickly measure the resistance of different pavement layers. This device causes a small destruction on the surface. Hence, it is also called nondestructive testing. However, to use DCP, it is necessary to measure its results with the results of prevalent and widely used tests such as CBR and to examine their relationships. In this research, the DCP, CBR, density, sieve analysis, moisture content, and Atterberg limit tests were performed on two locations (a highway under construction and a landscaping project). Then, the results of the DCP test with CBR and soil compaction ratio (R) in two different locations were investigated and the relationships between these parameters were determined. The results showed that there is a good relationship statistically between DCP and CBR parameters in both locations. Also, for the first time, a very good correlation between the R parameter and the results of the dynamic penetrometer cone test was obtained. The observations represented that the correlation coefficients are higher than 0.9 in the highway location, which had well-graded soil in comparison with the landscaping project.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141693318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Bhuvaneshwari, Bodu Suchitra, Ramachandran Divya
The present study aimed to experimentally and numerically analyze voided geopolymer concrete slabs applied with soft impact through a drop-hammer impact setup. Six slabs (600 mm ×600 mm × 115 mm) were cast using geopolymer concrete. Two were cast as solid slabs and the remaining four slabs were cast as voided slabs by placing a 70 mm diameter spherical void formers in two different patterns. Two patterns of void formers are followed as 70 mm void former at 240 mm spacing and 70 mm void former at 120 mm spacing. Micro steel fiber at a dosage of 1 % by volume fraction was added in companion specimens in each case. The placing of void former reduced the self-weight of the slabs by 6 % and 12.6 %, respectively, compared to solid slabs. The soft impact was achieved by releasing a 4.5 kg steel ball from a fall height of 0.457 m in a fabricated soft impact test frame. A similar soft impact test was accomplished numerically using the analysis system (ANSYS) workbench. Parametric analysis shows that when compared to fiber-reinforced solid slabs, the impact resistance of fiber-reinforced voided slabs with 70 mm void former at 240 mm was enhanced. The enhancement percentage for energy absorption, ductility index, and ultimate crack resistance were 34.05 %, 55.26 %, and 9.68 %, respectively. The fiber-reinforced voided slabs were also found to be economical and sustainable with reduced CO2 emission and embodied energy.
{"title":"Toughness Characteristics of Microfiber-Based Geopolymer Concrete Voided Slabs under Soft Impact","authors":"P. Bhuvaneshwari, Bodu Suchitra, Ramachandran Divya","doi":"10.1520/jte20230634","DOIUrl":"https://doi.org/10.1520/jte20230634","url":null,"abstract":"\u0000 The present study aimed to experimentally and numerically analyze voided geopolymer concrete slabs applied with soft impact through a drop-hammer impact setup. Six slabs (600 mm ×600 mm × 115 mm) were cast using geopolymer concrete. Two were cast as solid slabs and the remaining four slabs were cast as voided slabs by placing a 70 mm diameter spherical void formers in two different patterns. Two patterns of void formers are followed as 70 mm void former at 240 mm spacing and 70 mm void former at 120 mm spacing. Micro steel fiber at a dosage of 1 % by volume fraction was added in companion specimens in each case. The placing of void former reduced the self-weight of the slabs by 6 % and 12.6 %, respectively, compared to solid slabs. The soft impact was achieved by releasing a 4.5 kg steel ball from a fall height of 0.457 m in a fabricated soft impact test frame. A similar soft impact test was accomplished numerically using the analysis system (ANSYS) workbench. Parametric analysis shows that when compared to fiber-reinforced solid slabs, the impact resistance of fiber-reinforced voided slabs with 70 mm void former at 240 mm was enhanced. The enhancement percentage for energy absorption, ductility index, and ultimate crack resistance were 34.05 %, 55.26 %, and 9.68 %, respectively. The fiber-reinforced voided slabs were also found to be economical and sustainable with reduced CO2 emission and embodied energy.","PeriodicalId":17109,"journal":{"name":"Journal of Testing and Evaluation","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141688976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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