Shrinkage Characteristics and Modeling of Cement Stabilized Road Pavement Bases: A Compaction Delay Investigation

2018 ◽  
Vol 775 ◽  
pp. 610-617
Author(s):  
Patcharapan Nanthavisit ◽  
Peerapong Jitsangiam ◽  
Hamid Nikraz ◽  
Preda Pichayapan
Keyword(s):  
Time Delay ◽  
Failure Modes ◽  
Cement Content ◽  
Early Stage ◽  
Base Material ◽  
Negative Consequences ◽  
Road Pavement ◽  
Compaction Time ◽  
Base Course ◽  
Cement Stabilized Base

One of the main failure modes of a cement-stabilized road pavement base is the shrinkage cracking which could lead to negative consequences up to the failure of road pavements. The compaction time delay and cement content inherently affect to the shrinkage characteristics of the cement stabilized base course. This research aims to investigate the shrinkage characteristics with respect to the compaction time delay of a cement-stabilized base material through laboratory experiments. A series of shrinkage tests were performed on cement stabilized base samples with varying 3%, 4% and 5% of cement contents under controlled compaction delay periods varied from 0.5 hours to 1 day. The results of this study showed that shrinkage values of the study cement stabilized base increase with longer compaction time delay periods and cement contents. In addition, during an early stage (1-14 days) of shrinkage tests, shrinkage sharply increases before reaching the stage of a relatively constant rate after 14 days of testing. It would also be further notice that around 80% of the maximum shrinkage values from all tests gains in a test period between 14-21 days out of 42 days of a total shrinkage measurement period. Finally, the mathematic shrinkage model was formulated based on the test results of the study. In the model, the main factors of compaction delay time, cement content, and curing periods were used as the model variables. Shrinkage values can be predicted with a reliability of the R2 value of 0.6755.

Cement Content of Durability Cement Stabilized Macadam Base Course in Seasonal Freezing Zone

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Junchen Ma ◽  
Chunyu Liang ◽  
Ying Wang ◽  
Lidong Zhang ◽  
Weiwu Cui ◽  
...  
Keyword(s):  
Cement Content ◽  
Seasonal Freezing ◽  
Base Course

scholarly journals The Limestone as a Materials Combination of Base Course on the Road Pavement

2021 ◽  
Vol 1125 (1) ◽  
pp. 012019
Author(s):  
Yosef Cahyo Setianto Poernomo ◽  
Sigit Winarto ◽  
Zendy Bima Mahardana ◽  
Dwifi Aprillia Karisma ◽  
Rekso Ajiono
Keyword(s):  
The Road ◽  
Road Pavement ◽  
Base Course ◽  
On The Road

scholarly journals Evaluation of Energy Absorption Capabilities of Polyethylene Foam under Impact Deformation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3613
Author(s):  
Baohui Yang ◽  
Yangjie Zuo ◽  
Zhengping Chang
Keyword(s):  
Energy Absorption ◽  
Failure Modes ◽  
High Strain ◽  
Early Stage ◽  
High Energy ◽  
Test Method ◽  
Test Theory ◽  
Strain Rates ◽  
Impact Properties ◽  
The Impact

Foams are widely used in protective applications requiring high energy absorption under impact, and evaluating impact properties of foams is vital. Therefore, a novel test method based on a shock tube was developed to investigate the impact properties of closed-cell polyethylene (PE) foams at strain rates over 6000 s−1, and the test theory is presented. Based on the test method, the failure progress and final failure modes of PE foams are discussed. Moreover, energy absorption capabilities of PE foams were assessed under both quasi-static and high strain rate loading conditions. The results showed that the foam exhibited a nonuniform deformation along the specimen length under high strain rates. The energy absorption rate of PE foam increased with the increasing of strain rates. The specimen energy absorption varied linearly in the early stage and then increased rapidly, corresponding to a uniform compression process. However, in the shock wave deformation process, the energy absorption capacity of the foam maintained a good stability and exhibited the best energy absorption state when the speed was higher than 26 m/s. This stable energy absorption state disappeared until the speed was lower than 1.3 m/s. The loading speed exhibited an obvious influence on energy density.

Sample selection of prognostics validation test based on multi-stage Wiener process

2018 ◽  
Vol 233 (4) ◽  
pp. 605-614
Author(s):  
Zhiao Zhao ◽  
Yong Zhang ◽  
Guanjun Liu ◽  
Jing Qiu
Keyword(s):  
Wiener Process ◽  
Process Model ◽  
Failure Modes ◽  
Early Stage ◽  
Sample Selection ◽  
Degradation Process ◽  
Time Interval ◽  
Degradation Data ◽  
Multi Stage ◽  
Selection Of

Sample allocation and selection technology is of great significance in the test plan design of prognostics validation. Considering the existing researches, the importance of prognostics samples of different moments is not considered in the degradation process of a single failure. Normally, prognostics samples are generated under the same time interval mechanism. However, a prognostics system may have low prognostics accuracy because of the small quantity of failure degradation and measurement randomness in the early stage of a failure degradation process. Historical degradation data onto equipment failure modes are collected, and the degradation process model based on the multi-stage Wiener process is established. Based on the multi-stage Wiener process model, we choose four parameters to describe different degradation stages in a degradation process. According to four parameters, the sample selection weight of each degradation stage is calculated and the weight of each degradation stage is used to select prognostics samples. Taking a bearing wear fault of a helicopter transmission device as an example, its degradation process is established and sample selection weights are calculated. According to the sample selection weight of each degradation process, we accomplish the prognostics sample selection of the bearing wear fault. The results show that the prognostics sample selection method proposed in this article has good applicability.

scholarly journals Pavement Crack Detection from Hyperspectral Images Using a Novel Asphalt Crack Index

2020 ◽  
Vol 12 (18) ◽  
pp. 3084 ◽  
Author(s):  
Mohamed Abdellatif ◽  
Harriet Peel ◽  
Anthony G. Cohn ◽  
Raul Fuentes
Keyword(s):  
Crack Detection ◽  
Early Stage ◽  
Visible Spectrum ◽  
Hyperspectral Data ◽  
Hyperspectral Images ◽  
Surface Material ◽  
Pavement Condition ◽  
The Road ◽  
Road Pavement ◽  
Crack Index

Detection of road pavement cracks is important and needed at an early stage to repair the road and extend its lifetime for maintaining city roads. Cracks are hard to detect from images taken with visible spectrum cameras due to noise and ambiguity with background textures besides the lack of distinct features in cracks. Hyperspectral images are sensitive to surface material changes and their potential for road crack detection is explored here. The key observation is that road cracks reveal the interior material that is different from the worn surface material. A novel asphalt crack index is introduced here as an additional clue that is sensitive to the spectra in the range 450–550 nm. The crack index is computed and found to be strongly correlated with the appearance of fresh asphalt cracks. The new index is then used to differentiate cracks from road surfaces. Several experiments have been made, which confirmed that the proposed index is effective for crack detection. The recall-precision analysis showed an increase in the associated F1-score by an average of 21.37% compared to the VIS2 metric in the literature (a metric used to classify pavement condition from hyperspectral data).

scholarly journals Flexural Behavior of Fire-Damaged Prefabricated RC Hollow Slabs Strengthened with CFRP versus TRM

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2556
Author(s):  
Zheng-Ang Sui ◽  
Kun Dong ◽  
Jitong Jiang ◽  
Shutong Yang ◽  
Kexu Hu
Keyword(s):  
Failure Modes ◽  
Early Stage ◽  
Load Capacity ◽  
Peak Load ◽  
Flexural Behavior ◽  
Masonry Building ◽  
Fire Exposure ◽  
Standard Fire ◽  
Four Point Bending ◽  
Strengthening Technique

In this paper, carbon fiber reinforced polymer (CFRP) and textile reinforced mortar (TRM) strengthening techniques were proposed to retrofit and strengthen fire-damaged prefabricated concrete hollow slabs. A total of six slabs, from an actual multi-story masonry building, were tested to investigate the flexural performance of reinforced concrete (RC) hollow slabs strengthened with TRM and CFRP. The investigated parameters included the strengthening method (CFRP versus TRM), the number of CFRP layers, and with or without fire exposure. One unstrengthened slab and one TRM strengthened slab served as the control specimens without fire exposure. The remaining four slabs were first exposed to ISO-834 standard fire for 1 h, and then three of them were strengthened with CFRP or TRM. Through the four-point bending tests at ambient temperature, the failure modes, load and deformation response were recorded and discussed. Both CFRP and TRM strengthening methods can significantly increase the cracking load and peak load of the fire-damaged hollow slabs, as well as the stiffness in the early stage. The prefabricated hollow slabs strengthened by CFRP have better performance in the ultimate bearing capacity, but the ductility reduced with the increase of CFRP layers. Meanwhile, the TRM strengthening technique is a suitable method for the performance improvement of fire-damaged hollow slabs, in terms of not only the load capacity, especially the cracking load, but also the flexural stiffness and deformation capacity.

scholarly journals Evaluation on Strength Properties of Lime–Slag Stabilized Loess as Pavement Base Material

2019 ◽  
Vol 11 (15) ◽  
pp. 4099 ◽  
Author(s):  
Liang Jia ◽  
Li Zhang ◽  
Jian Guo ◽  
Kai Yao ◽  
Sin Mei Lim ◽  
...  
Keyword(s):  
Base Material ◽  
Correlation Coefficients ◽  
Strength Properties ◽  
Binder Content ◽  
Curing Time ◽  
Test Results ◽  
Base Course Material ◽  
Course Material ◽  
Base Course ◽  
Pavement Base

This study aimed to investigate the feasibility of using lime–slag stabilized loess as base-course material by assessing its unconfined compressive strength (UCS). Loess stabilized with various mix ratios were compacted and cured to three, five, seven, and 28 days, respectively, for further strength tests. The effects of binder content, lime-to-slag (L/S) ratio, porosity, and curing time on the UCS of stabilized loess were addressed in detail. The test results show that UCS increases with the increase in binder content or curing time, and it gains strength rapidly within the first seven days of curing. At the same binder content, UCS decreases with the decrease in L/S ratio or porosity. Finally, the correlations of UCS with binder content, porosity, and curing time were derived, which exhibited reasonable correlation coefficients R2 (from 0.86 to 0.97).

Preventive Maintenance for Roller and Journal Bearings of Induction Motor Based on the Diagnostic Signature Analysis

1986 ◽  
Vol 108 (1) ◽  
pp. 26-31 ◽  
Author(s):  
T. Koizumi ◽  
M. Kiso ◽  
R. Taniguchi
Keyword(s):  
Preventive Maintenance ◽  
Diagnostic Procedure ◽  
Failure Modes ◽  
Induction Motors ◽  
Early Stage ◽  
Diagnostic System ◽  
Journal Bearings ◽  
Diagnostic Signature ◽  
Almost All ◽  
Practical Field

This paper is concerned with the preventive maintenance of roller and journal bearings installed in induction motors. Almost all kinds of failure modes happening on both roller and journal bearings have been reproduced and classified using time and frequency domain data analysis. Diagnostic procedure also has been derived using these analyzed results and statistical method. Finally, an actual diagnostic system for the early stage detection of defected roller bearings has been developed for practical field use.

A Fuzzy Logic Based Rocket Launch Tube’s DFMEA

2011 ◽  
Vol 87 ◽  
pp. 119-122
Author(s):  
Tosapolporn Pornpibunsompop ◽  
Attapon Charoenpon ◽  
Ekaratch Pankaew
Keyword(s):  
Fuzzy Logic ◽  
Failure Modes ◽  
Mechanical Load ◽  
Material Selection ◽  
Early Stage ◽  
Rule Base ◽  
Fuzzy Logic Approach ◽  
Logic Approach ◽  
Potential Failure ◽  
Launch Tube

DFMEA is a significantly efficient tool to systematically evaluate risk in early stage of product design and development but some of knowledge and information are uncertain and imprecise. This research focuses on fuzzy logic approach to diminish weaknesses and applies to launch tube’s DFMEA. The methodology started from determine membership function of severity, occurrence, and detection and provide fuzzy rule base to arranged category of risk. Afterwards, center average index was selected as defuzzifier for risk value representation. Consequently, the prioritization based on risk value was done and chosen the first five risk value of potential failure modes to analyze causes then recommended appropriate actions. After application of fuzzy logic approach, the most vital potential failure mode is damaged launch tube due to detention force which is rated as first and second priority depending on potential cause or mechanism. The third priority is launch tube distortion. The mechanical load calculation and proper material selection are the recommended actions for overcoming those potential failure modes.

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