scholarly journals Enhanced Flexible Pavement Performance Using Treated Compared to Untreated Aggregate Bases: A Comparative Case Study in the Southern United States

2021 ◽  
Vol 6 (8) ◽  
pp. 110
Author(s):  
Mena I. Souliman ◽  
Hemant GC ◽  
Zabi Mohammed
Keyword(s):  
Surface Roughness ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Base Material ◽  
Fatigue Cracking ◽  
Base Layer ◽  
Pavement Performance ◽  
Comparative Case Study ◽  
Stabilizing Agents ◽  
The Impact

One of the important aspects of highway design is aggregates. Aggregates strength and consistency has an effect on pavement structure’s overall performance. The consistency of the base material near the site of the construction doesn’t always match the requirements of pavement construction and carrying quality aggregate raises the cost of construction. Stabilizing agents such as asphalt cement, lime, fly ash were used to improve the strength of these materials in order to make greater use of locally available materials. Layer materials present in the pavements and the structure of them influence pavement performance. The compressive strain and the tensile strain in the layer of subgrade and asphalt layer respectively are influenced by the stiffness of the base layer. The important aspects causing rutting and fatigue cracking are compressive strain in the top region of the subgrade layer and tensile strain at the bottom of the asphalt layer, respectively. In this research study, field performance (cracking, rutting, and surface roughness) of pavement sections with untreated and treated bases were collated to assess the impact of the stabilizing agents. The treated sections performed well significantly compared to the untreated sections in terms of pavement surface roughness and fatigue cracking. The treated sections performed higher than the untreated sections in terms of the cumulative average values of all 3 distresses with fatigue cracking averaging 5 times lower than the untreated sections. The combined IRI and rutting of treated sections averaged about 1.5 times and 0.11 inches smaller, respectively than those of untreated sections.

scholarly journals Performance analysis of flexible pavements with base lime

2021 ◽  
Author(s):  
Mena I. Souliman ◽  
Nitish R. Bastola
Keyword(s):  
Compressive Strain ◽  
Fatigue Cracking ◽  
Base Layer ◽  
Stabilizing Agent ◽  
Climate Conditions ◽  
Stabilizing Agents ◽  
Concrete Layer ◽  
Pavement Structure ◽  
Materials Used

The performance of the pavement is influenced by several factors, such as the pavement structure, materials, traffic, and climate conditions. These factors affect the pavement response, mainly the compressive strain developed at the top of each layer and the tensile strain developed at the bottom of the asphalt concrete layer, resulting in various forms of distresses, such as fatigue cracking. The materials used in the construction of these layers are equally important for the long-term performance of the pavements as well as its structural stability. Aggregates are the most used materials in the construction of base layers in a flexible pavement structure. Moreover, the aggregate used in the base layer provides foundation for the overlying layers and needs to have enough strength, but due to the scarcity of quality materials and the rising demand, base layers are often treated with different types of stabilizing agents. In this study, various mechanistic analyses are performed using the 3-D Move Analysis software to study the effects of lime as a stabilizing agent on fatigue resistance performance. These analyses showed that the use of lime as a stabilizing agent increased the pavement performance up to 48 % for fatigue cracking resistance when compared to untreated base layers. The cost-effectiveness analysis also showed that the use of stabilizing agents would reduce the long-term cost of pavement as compared to untreated bases. The overall cost efficiency of the lime treated base is found to be 1.68 times the untreated base.

Treated versus Untreated Aggregate Bases for Flexible Pavements: Nationwide Comparative Case Study

2020 ◽  
Vol 2674 (2) ◽  
pp. 225-236
Author(s):  
Mena I. Souliman ◽  
Hemant GC ◽  
Mayzan M. Isied ◽  
Lubinda F. Walubita
Keyword(s):  
Field Performance ◽  
Fatigue Cracking ◽  
Base Layer ◽  
Comparative Case Study ◽  
International Roughness Index ◽  
Stabilizing Agents ◽  
Asphalt Cement ◽  
Subgrade Soils ◽  
Subgrade Soil ◽  
Pavement Construction

Aggregates constitute a major part of pavement construction. The strength, durability, and quality of the aggregate affects the overall performance of the pavement structure. Materials sourced near a construction site do not always meet the strength required for pavement construction, however, and haulage of aggregates of the required quality is often costly. For better use of locally available materials, stabilizing agents such as lime, cement, asphalt cement, and fly ash are often used to enhance the strength of the local aggregates. Pavement performance is influenced by both the structure itself and the layer materials present in it. The stiffness of the base layer, for instance, influences the tensile strain in the asphalt layer and compressive strains in the subgrade soil. The tensile strains at the bottom of the asphalt layer and compressive strains in the top zone of the subgrade soils are the main response components affecting fatigue cracking and rutting, respectively. In this study, field performance [rutting, cracking, and roughness measured in relation to the International Roughness Index (IRI)] of pavement sections with treated and untreated base layers were compared to determine the effects of stabilizing agents. In relation to fatigue cracking and pavement surface roughness, the treated sections outperformed the untreated sections. The average values of all three distresses showed better performance for the treated base layer sections with fatigue cracking averaging 2.2 times lower than the untreated sections. The combined rutting and IRI of the treated base layer sections averaged about 0.10 in. and 1.4 times lower than those of the untreated base layer sections, respectively.

scholarly journals Influence of moisture infiltration on flexible pavement cracking and optimum timing for surface seals

2020 ◽  
Vol 47 (5) ◽  
pp. 487-497 ◽  
Author(s):  
Syed Waqar Haider ◽  
Muhammad Munum Masud ◽  
Karim Chatti
Keyword(s):  
Service Life ◽  
Monitoring Program ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
Time Domain Reflectometry ◽  
Water Infiltration ◽  
Base Layer ◽  
Pavement Performance ◽  
Ann Model ◽  
Premature Failure

Moisture increase in pavement subsurface layers has a significant influence on granular material properties that affect the expected pavement performance. In situ moisture variations over time in an unbound base layer depend on water infiltration after precipitation and pavement surface conditions. Consequently, base resilient modulus (MR) is reduced, which leads to premature failure and reduced service life. This paper presents long-term pavement performance (LTPP) data analyses for quantifying the effect of moisture infiltration through surface cracking on flexible pavement performance. Subsurface moisture data obtained through the seasonal monitoring program (SMP) time domain reflectometry (TDR) are an excellent source for quantifying the moisture-related damage in flexible pavement located in different climates. An artificial neural network (ANN) model was developed based on the SMP data for flexible pavement sections. The results show that higher levels of cracking will lead to an increase in moisture levels within the base layer, which leads to a significant decrease in the base MR. For flexible pavement, the maximum reduction in base MR ranged from 18% to 41% and from 153% to 175% for the pavement sections located in dry and wet regions, respectively. Consequently, the performance of pavement sections located in wet climates is adversely affected. The findings imply that an adequate and timely preservation treatment for cracking sealing (e.g., surface seals) can enhance the pavement’s service life, especially in wet climates. The results suggest that cracks should be sealed when the extent of fatigue cracking is within 6% and 11% for the flexible pavement sections located in wet and dry climates, respectively.

scholarly journals Influence of Modulus of Base Layer on The Strain Distribution for Asphalt Pavement

2021 ◽  
Vol 16 (4) ◽  
pp. 126-152
Author(s):  
Kang Yao ◽  
Xin Jiang ◽  
Jin Jiang ◽  
Zhonghao Yang ◽  
Yanjun Qiu
Keyword(s):  
Strain Distribution ◽  
Tensile Strain ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Element Model ◽  
Neutral Axis ◽  
Base Layer ◽  
Maximum Tensile Strain

In order to investigate the influence of modulus of the base layer on the strain distribution for asphalt pavement, the modulus ratio of the base layer and the AC layer (Rm) is introduced as a controlled variable when keeping modulus of the AC layer as a constant in this paper. Then, a three-layered pavement structure is selected as an analytical model, which consists of an AC layer with the constant modulus and a base layer with the variable modulus covering the subgrade. A three dimensional (3D) finite element model was established to estimate the strains along the horizontal and vertical direction in the AC layer under different Rm. The results show that Rm will change the distribution of the horizontal strains along the depth in the AC layer; the increase of Rm could reduce the maximum tensile strain in the AC layer, but its effect is limited; the maximum tensile strain in the AC layer does not necessarily occur at the bottom, but gradually rises to the middle with the increase of Rm. Rm could significantly decline the bottom strain in the AC layer, and there is a certain difference between the bottom and the maximum strain when Rm is greater than or equal to one, which will enlarge with increasing Rm. Rm could change the depth of the neutral axis in the AC layer, and the second neutral axis will appear at the bottom of the AC layer under a sufficiently large Rm. The average vertical compressive strain in the AC layer will significantly enlarge with the increase of Rm.

scholarly journals The Effect of Coca Cola Drink on the Impact Strength and Surface Roughness of Acrylic Denture Base

2018 ◽  
Vol 2 (2) ◽  
pp. 120-131
Author(s):  
Fahd Ikram
Keyword(s):  
Surface Roughness ◽  
Impact Strength ◽  
Plastic Material ◽  
Base Material ◽  
Control Group ◽  
Denture Base ◽  
Heat Cure ◽  
Base Resin ◽  
Group A ◽  
The Impact

Despite the development of many denture base material like chrome-cobalt, fluid and plastic material but the heat cure polymethylmethacrylate considered as the most widely used denture base material. The aims of this study to evaluate and compare the impact strength and surface roughness of heat cured denture base resin after immersing incoca-cola drink for two and four weeks. Methods: A total number of 40 samples were prepared, 30 samples for impact strength test and 10 samples for surface roughness test. The samples were divided into three group; A (control), B (2 weeks immersed in coca cola drink), and C (4 weeks immersed in coca cola drink). Result: Data analyzed by using SPSS software with ANOVA test indicated a non significant differences between the different tested groups, however the samples that were immersed in coca cola drink for 4 weeks revealed non dramatic increase in surface roughness, while the samples that were immersed for 2 weeks showed a non dramatic decrease in the impact strength. Conclusions: The coca cola drink non significantly caused dropping in the tested properties in comparison to the control group.

A Study on the Impact of the Milling Parameters on the Surface Roughness when Using Polyurethane Board as a Base Material in Manufacturing Automotive Checking Fixtures

2015 ◽  
Vol 819 ◽  
pp. 449-454 ◽  
Author(s):  
Louis Denis Kevin Catherine ◽  
Raja Aziz Raja Ma’arof ◽  
Sangeeth Suresh
Keyword(s):  
Surface Roughness ◽  
Seat Belt ◽  
Base Material ◽  
Influential Factor ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Dry Cutting ◽  
Milling Parameters ◽  
Step Over ◽  
The Impact

The improvement of the quality of the surface roughness of the polyurethane board (PB) has always been a challenge in the automotive industry. A suitable combination of the milling parameters is very important in order to get a high grade of smoothness specially when dealing with complex designs such as curved profiles. In this paper, a half factorial design of experiment (DoE) with 16 runs at two levels is applied in the milling operation of the checking fixtures of a car seat belt bracket under a dry cutting condition. The Feed rate, Depth of cut, Spindle speed, Step over and Plunge rate were taken as the variables for the DoE. Two different milling tools, a flat end mill of diameter10 mm for roughing, and a ball nose of diameter 5 mm for the finishing process were used. Minitab software was use to analyze the correlation between the parameters and the surface roughness. The most influential factor in the milling process was observed to be the Step over.

Compressive and Tensile Strain Capacities of 48” X80 Line Pipes

2012 ◽  
Author(s):  
Hisakazu Tajika ◽  
Satoshi Igi ◽  
Takahiro Sakimoto ◽  
Shigeru Endo ◽  
Seishi Tsuyama ◽  
...  
Keyword(s):  
Tensile Strain ◽  
High Strain ◽  
Uniform Elongation ◽  
Compressive Strain ◽  
Experimental Studies ◽  
Local Buckling ◽  
Base Material ◽  
Pipe Surface ◽  
Strain Capacity ◽  
Strain Limit

This paper presents the results of experimental studies focused on the strain capacity of X80 linepipe. A full-scale bending tests of X80 grade, 48″ high-strain linepipes pressurized to 60% SMYS were conducted to investigate the compressive strain limit and tensile strain limit. The tensile properties Y/T ratios and uniform elongation of the pipes had variety. Three of four pipes are high strain pipes and these Y/T ratios are intentionally low with manufacturing method. One of these high-strain pipe was girth welded in its longitudinal center to investigate the effect of girth weld to strain capacity. The other was set as a conventional pipe that have higher Y/T ratio to make comparative study. The compressive strain limit focused on the critical strain at the formation of local buckling on the compression side of bending. After pipe reaches its endurable maximum moment, one large developed wrinkle and some small wrinkles on the pipe surface during bending deformation were captured relatively well from observation and strain distribution measurement. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation/propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and rupture in the base material at the tension (opposite) side of the local buckling position.

Middle-Up Cracking Potential in Flexible Pavements with Stabilized Foundations

2021 ◽  
pp. 036119812199069
Author(s):  
Mostafa Nakhaei ◽  
David H. Timm
Keyword(s):  
Tensile Strain ◽  
Elevated Temperatures ◽  
Compressive Strain ◽  
Flexible Pavements ◽  
Fatigue Cracking ◽  
Full Scale ◽  
Computational Simulations ◽  
Cracking Potential ◽  
Maximum Tensile Strain ◽  
New Perspective

This investigation presents a new perspective on the structural behavior of stabilized foundation pavements through full-scale testing and simulation where the historical premise of bottom-up fatigue cracking has been challenged. Two full-scale pavement sections were constructed at the National Center for Asphalt Technology Test Track in 2018. One section featured a stabilized foundation under the asphalt layers while the other was a thick-lift asphalt section on conventional base and subgrade materials. Both sections were embedded with pavement response instrumentation and their behavior was observed over time under accelerated truck trafficking. In addition, computational simulations were executed to explain the observed behavior. The strain measurement at the bottom of the asphalt concrete (AC) for the thick-lift section showed a familiar trend in which the tensile strain at the bottom of the AC increased exponentially with temperature. In contrast, the strain at the bottom of the AC in the stabilized foundation pavement was predominantly in compression at elevated temperatures. Further analysis revealed that compressive strain at the bottom of the AC increased exponentially with temperature similar to conventional flexible pavements but with a reversed sign. The results were confirmed by falling weight deflectometer testing that was conducted directly above the embedded pavement sensors. Computational simulations confirmed the behavior and suggested that the maximum tensile strain could occur at shallower depths, possibly mid-depth of the AC, in stabilized foundation pavements. This indicates stabilized foundation pavements could be prone to middle-up cracking and subsequent precautions should be taken to avoid middle-up fatigue cracking.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

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