scholarly journals A Case of Minimally Structural Deterioration in Starr-Edwards Caged-Disk Valve 39 Years after Implantation

2017 ◽  
Vol 46 (6) ◽  
pp. 282-284
Author(s):  
Koji Akasu ◽  
Tomofumi Fukuda ◽  
Kosuke Saku ◽  
Keishi Hashimoto ◽  
Satoshi Kikusaki ◽  
...  
Keyword(s):  
Structural Deterioration ◽  
Disk Valve

scholarly journals Durability Study on High-Performance Fiber-Reinforced Mortar under Simulated Wastewater Pipeline Environment

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3781
Author(s):  
Tianyu Wang ◽  
Yahong Zhao ◽  
Baosong Ma ◽  
Cong Zeng
Keyword(s):  
Mass Loss ◽  
Pore Volume ◽  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Economic Losses ◽  
Structural Deterioration ◽  
Simulated Wastewater ◽  
Corrosive Environments

The acid–alkaline-inducd corrosive environments inside wastewater concrete pipelines cause concrete structural deterioration and substantial economic losses all over the world. High-performance concrete/mortar (HPC) was designed to have better resistance to corrosive environments, with enhanced service life. However, the durability of HPC in wastewater pipeline environments has rarely been studied. A high-performance mortar mixture (M) reinforced by supplemental materials (including fly ash and silica fume) and polyvinyl alcohol (PVA) fibers, together with a mortar mixture (P) consisting of cement, sand and water with similar mechanical performance, were both designed and exposed to simulated wastewater pipeline environments. The visual appearance, dimensional variation, mass loss, mechanical properties, permeable pore volume, and microstructure of the specimens were measured during the corrosion cycles. More severe deterioration was observed when the alkaline environment was introduced into the corrosion cycles. Test results showed that the M specimens had less permeable pore volume, better dimensional stability, and denser microstructure than the P specimens under acid–alkaline-induced corrosive environments. The mass-loss rates of the M specimens were 66.1–77.2% of the P specimens after 12 corrosion cycles. The compressive strength of the M specimens was 25.5–37.3% higher than the P specimens after 12 cycles under corrosive environments. Hence, the high-performance mortar examined in this study was considered superior to traditional cementitious materials for wastewater pipeline construction and rehabilitation.

Conceptualization of Three-Stage Fatigue Failure in Asphalt-Rubber Gap-Graded Mixtures using Dynamic Semi-Circular Bending Test

2020 ◽  
Vol 2674 (7) ◽  
pp. 44-55
Author(s):  
Veena Venudharan ◽  
Krishna Prapoorna Biligiri
Keyword(s):  
Failure Process ◽  
Mouth Opening ◽  
Fatigue Performance ◽  
Bending Test ◽  
Crack Mouth Opening Displacement ◽  
Fatigue Process ◽  
Structural Deterioration ◽  
Asphalt Rubber ◽  
Scb Test ◽  
Cracking Mechanism

The objective of this study was to qualitatively measure the cracking mechanism of asphalt-rubber gap-graded (AR-Gap) mixtures and compare the methodical approach proposed in this research with the conventional fatigue process. As part of experimentation plan, dynamic a semi-circular bending (SCB) test was conducted on 27 AR-Gap mixtures with varying mix parameters, including, binder type, binder content, and aggregate gradation. Fatigue life ( Nf) obtained from the dynamic SCB test was analyzed from a statistical viewpoint, and key relationships that potentially contribute to fatigue performance were identified. Later, crack mouth opening displacement (CMOD) was used to study the cracking mechanism of AR-Gap mixtures. CMOD data were analyzed using the Francken model that theorizes the accumulated damage as a three-stage failure. Further, fatigue tertiary life ( Nft) was determined on the premise of structural deterioration obtained from the three-stage failure process. The fatigue disparity factor (ξ), the ratio of Nf to Nft for each asphalt mix was estimated to compare fatigue performance indices. The score of ξ for all the mixtures exceeded 50%, which was indicative of longer crack initiation and crack propagation phase over the third stage of the fatigue cracking mechanism. Overall, the fatigue mechanism was explained through the conceptualization of the three-stage fatigue process through various intrinsic properties of AR-Gap mixtures.

scholarly journals Cortical thinning and accumulation of large cortical pores in the tibia reflect local structural deterioration of the femoral neck

Bone ◽  
2020 ◽  
Vol 137 ◽  
pp. 115446 ◽  
Author(s):  
Gianluca Iori ◽  
Johannes Schneider ◽  
Andreas Reisinger ◽  
Frans Heyer ◽  
Laura Peralta ◽  
...  
Keyword(s):  
Femoral Neck ◽  
Cortical Thinning ◽  
Structural Deterioration

A Practical Computing Method for Residual Area of Rebar Cross-Sections under Carbonation Induced Corrosion

2012 ◽  
Vol 166-169 ◽  
pp. 1895-1899
Author(s):  
Xiao Gang Wang ◽  
De Ming Zhong
Keyword(s):  
Cross Sections ◽  
Laser Scanning ◽  
Major Axis ◽  
Structural Deterioration ◽  
Minimum Residual ◽  
Degree Of Confidence ◽  
Conservative Approximation ◽  
Rc Slabs ◽  
Computing Method ◽  
Geometric Measurement

Area loss of severely weakened rebar cross sections is a crucial variable in assessment of structural deterioration for corroded concrete structures, which is hard to be measured or estimated precisely in conventional methods. In this paper, rebar samples were taken from naturally corroded RC slabs. Their virtual models were built using 3D laser scanning technique to facilitate geometric measurement. From these models seriously weakened sections were screened out as analyzing samples, and residual areas as well as profiles of the cross-sections were derived and investigated consequently. Shown by the results, corrosion was non-uniformly distributed on rebar surface, and profiles of the residual cross-sections can hardly be formulated efficiently. However, they can be simplified into ellipse with minor axis of minimum residual diameter and major axis of diameter in perpendicular direction. This model has been proved to give an conservative approximation of residual sectional area with 4.27% underestimation and 89.2% degree of confidence.

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