Laboratory and Field Evaluation of Single Layer and Double Layer High Friction Surface Treatments

2019 ◽  
Vol 2673 (2) ◽  
pp. 552-561 ◽  
Author(s):  
Shuo Li ◽  
Peiliang Cong ◽  
Demei Yu ◽  
Rui Xiong ◽  
Yi Jiang
Keyword(s):  
Double Layer ◽  
Friction Surface ◽  
Single Layer ◽  
Aggregate Size ◽  
Surface Friction ◽  
Field Evaluation ◽  
The United States ◽  
Aggregate Gradation ◽  
State Highway ◽  
Friction Performance

High friction surface treatment (HFST) has been proactively used as a solution to extreme friction demands at locations such as horizontal curves, ramps, bridge decks, and intersections. Considerable efforts have been made to evaluate the use of HFST across the United States (U.S.) The American Association of State Highway and Transportation Officials (AASHTO) has issued a provisional specification, i.e., AASHTO PP 79-14, to help state Departments of Transportation (DOTs) to successfully apply HFST. This paper presents a further effort made by the authors to evaluate and compare the friction performance and durability of single and double layer HFTS systems with calcined bauxite aggregate. The laboratory accelerated polishing was conducted to evaluate the effects of aggregate candidate gradations on the friction performance, such as friction coefficient and macrotexture mean profile depth (MPD), and to determine the aggregate gradation for field evaluation. Field evaluation was conducted on both single and double layer HFST systems using test strips under actual traffic polishing over a time period of nine months that covered an entire snow season. It was found that larger aggregate size tends to yield larger MPD, but larger MPD does not necessarily imply larger friction. The double layer HFST did not outperform the single layer HFST with respect to friction and durability. If the properties of calcined bauxite aggregate are precisely defined, either surface friction or MPD can solely be utilized as the frictional metric for quality assurance (QA) of HFST.

scholarly journals Determination of Friction Performance of High Friction Surface Treatment Based on Alternative Macrotexture Metric

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6895
Author(s):  
Hua Zhao ◽  
Fulu Wei ◽  
Ce Wang ◽  
Shuo Li ◽  
Jie Shan
Keyword(s):  
Surface Treatment ◽  
Friction Surface ◽  
Surface Friction ◽  
Test System ◽  
Test Methods ◽  
Friction Test Methods ◽  
Profile Depth ◽  
Aggregate Loss ◽  
Friction Performance

Surface friction is currently the most common metric for evaluating the performance of high friction surface treatment (HFST). However, friction test methods such as the locked wheel skid tester (LWST) commonly provide a spot measurement. Large variations may arise in the LWST testing on curves. Based on 21 actual HFST projects, a study was performed to use a macrotexture metric, i.e., the mean profile depth (MPD) to evaluate HFST’s performance and improve its quality control (QC)/quality assurance (QA) procedures. The material properties were presented to understand the aspects of HFST. The method for calculating MPD was modified to account for the variations of macrotexture measurements. A vehicle-based test system was utilized to measure MPD periodically over an 18-month period since HFST installation. Statistical analysis was performed on the MPD measurements to identify the effects of influencing factors. Compared with the friction from LWST, MPD was equally effective in evaluating HFST performance. However, the use of MPD eliminated the errors as arisen in LWST testing and made it possible to detect surface distresses, including aggregate loss, delamination, and cracking. The expected overall MPD may be calculated by combining the MPD measurements made three months after installation at different HFST sites and used as a metric for evaluating HFST performance and QC/QA.

scholarly journals Investigation of Durability and Performance of High Friction Surface Treatment

2021 ◽  
Author(s):  
Fulu Wei ◽  
Ce Wang ◽  
Xiangxi Tian ◽  
Shuo Li ◽  
Jie Shan
Keyword(s):  
Surface Treatment ◽  
Friction Surface ◽  
Coefficient Of Thermal Expansion ◽  
Good Condition ◽  
Surface Friction ◽  
Loading Test ◽  
System Integrity ◽  
Chip Seal ◽  
Friction Performance ◽  
And Performance

The Indiana Department of Transportation (INDOT) completed a total of 25 high friction surface treatment (HFST) projects across the state in 2018. This research study attempted to investigate the durability and performance of HFST in terms of its HFST-pavement system integrity and surface friction performance. Laboratory tests were conducted to determine the physical and mechanical properties of epoxy-bauxite mortar. Field inspections were carried out to identify site conditions and common early HFST distresses. Cyclic loading test and finite element method (FEM) analysis were performed to evaluate the bonding strength between HFST and existing pavement, in particular chip seal with different pretreatments such as vacuum sweeping, shotblasting, and scarification milling. Both surface friction and texture tests were undertaken periodically (generally once every 6 months) to evaluate the surface friction performance of HFST. Crash records over a 5-year period, i.e., 3 years before installation and 2 years after installation, were examined to determine the safety performance of HFST, crash modification factor (CMF) in particular. It was found that HFST epoxy-bauxite mortar has a coefficient of thermal expansion (CTE) significantly higher than those of hot mix asphalt (HMA) mixtures and Portland cement concrete (PCC), and good cracking resistance. The most common early HFST distresses in Indiana are reflective cracking, surface wrinkling, aggregate loss, and delamination. Vacuum sweeping is the optimal method for pretreating existing pavements, chip seal in particular. Chip seal in good condition is structurally capable of providing a sound base for HFST. On two-lane highway curves, HFST is capable of reducing the total vehicle crash by 30%, injury crash by 50%, and wet weather crash by 44%, and providing a CMF of 0.584 in Indiana. Great variability may arise in the results of friction tests on horizontal curves by the use of locked wheel skid tester (LWST) due both to the nature of vehicle dynamics and to the operation of test vehicle. Texture testing, however, is capable of providing continuous texture measurements that can be used to calculate a texture height parameter, i.e., mean profile depth (MPD), not only for evaluating friction performance but also implementing quality control (QC) and quality assurance (QA) plans for HFST.

Rampart craters on Earth

2021 ◽  
Author(s):  
Gerwin Wulf ◽  
Thomas Kenkmann
Keyword(s):  
United States ◽  
Double Layer ◽  
Impact Crater ◽  
Single Layer ◽  
The United States ◽  
Impact Craters ◽  
Planetary Surfaces ◽  
Lonar Crater

ABSTRACT Rampart craters are omnipresent features on volatile-rich solid planetary surfaces. This raises the question whether, and how many, rampart craters are present on Earth. We reviewed the terrestrial impact crater record with regard to possible rampart morphologies and present detailed morphological analyses of these terrestrial craters here. Our results show that the Ries crater in Germany, Bosumtwi crater in Ghana, Tenoumer crater in Mauritania, Lonar crater in India, and Meteor crater in the United States are terrestrial rampart craters. The Ries and Bosumtwi craters can be classified as double-layer ejecta (DLE) craters, whereas Tenoumer, Lonar, and Meteor craters can be classified as single-layer ejecta (SLE) craters. Tenoumer and Meteor craters show rampart as well as common lunar-like ejecta characteristics within their ejecta blankets and, thus, appear to be hybrid craters. In addition, we discuss seven crater structures that show at least some morphological or lithological peculiarities that could provide evidence for possible ejecta ramparts. Considering the low number of terrestrial impact craters with well-preserved ejecta blankets, the relatively high proportion of rampart craters is astonishing. Obviously, the formation of layered or rampart craters is a common and not a rare process on Earth.

Field Evaluation of Surface Friction Performance of Chip Seals in Indiana

2012 ◽  
Vol 2295 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Shuo Li ◽  
Todd Shields ◽  
Samy Noureldin ◽  
Yi Jiang
Keyword(s):  
Field Performance ◽  
Surface Friction ◽  
Field Evaluation ◽  
Field Testing ◽  
Factors Affecting ◽  
Pavement Condition ◽  
Chip Seal ◽  
Chip Seals ◽  
Friction Performance ◽  
On Chip

Chip seal has been widely used as an effective surface treatment for pavement preservation. The Indiana Department of Transportation (DOT) chip sealed a total of 373 lane mile pavements in 2008 and 700 lane mile pavements in 2009. However, many issues, such as the optimal use of local materials and new aggregates, remained unsolved. No original information was available at the time for Indiana DOT engineers to assess the performance of chip seal pavements. A research study was initiated by the Indiana DOT to evaluate the field performance of chip seal pavements, particularly the surface friction properties. Eighteen chip seal projects were selected as the test sections for this study. Field testing was conducted to measure pavement surface friction and texture properties. The true surface friction numbers were identified for chip seals after 12 months of service. The variation of surface friction on chip seals was analyzed. Factors affecting chip seal surface friction, such as aggregate, traffic volume, and existing pavement condition, were identified and examined. Three traffic levels were defined for better chip seal application. The international roughness index on the existing pavement affected chip seal friction performance. A criterion was recommended for assessing the friction performance of chip seal and identifying the possible failure of a chip seal.

Cracking at the fold in double layer coated paper: the influence of latex and starch composition

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 93-99
Author(s):  
SEYYED MOHAMMAD HASHEMI NAJAFI ◽  
DOUGLAS BOUSFIELD, ◽  
MEHDI TAJVIDI
Keyword(s):  
Mechanical Properties ◽  
Double Layer ◽  
Starch Content ◽  
Single Layer ◽  
Double Layers ◽  
Coated Paper ◽  
Coated Papers ◽  
Coating Layers ◽  
Scanned Images ◽  
Packaging Paper

Cracking at the fold of publication and packaging paper grades is a serious problem that can lead to rejection of product. Recent work has revealed some basic mechanisms and the influence of various parameters on the extent of crack area, but no studies are reported using coating layers with known mechanical properties, especially for double-coated systems. In this study, coating layers with different and known mechanical properties were used to characterize crack formation during folding. The coating formulations were applied on two different basis weight papers, and the coated papers were folded. The binder systems in these formulations were different combinations of a styrene-butadiene latex and mixtures of latex and starch for two different pigment volume concentrations (PVC). Both types of papers were coated with single and double layers. The folded area was scanned with a high-resolution scanner while the samples were kept at their folded angle. The scanned images were analyzed within a constant area. The crack areas were reported for different types of papers, binder system and PVC values. As PVC, starch content, and paper basis weight increased, the crack area increased. Double layer coated papers with high PVC and high starch content at the top layer had more cracks in comparison with a single layer coated paper, but when the PVC of the top layer was low, cracking area decreased. No measurable cracking was observed when the top layer was formulated with a 100% latex layer.

Single layer versus double layer suture for anastomosis of the gastrointestinal tract

2009 ◽  
Author(s):  
Alvaro Sanabria ◽  
Gabriel Gomez ◽  
Eduardo Valdivieso ◽  
C Bermudez
Keyword(s):  
Gastrointestinal Tract ◽  
Double Layer ◽  
Single Layer ◽  
Layer Versus

Single layer versus double layer suture for anastomosis of the gastrointestinal tract

2005 ◽  
Author(s):  
Alvaro Sanabria ◽  
Gabriel Gomez ◽  
Eduardo Valdivieso ◽  
C Bermudez
Keyword(s):  
Gastrointestinal Tract ◽  
Double Layer ◽  
Single Layer ◽  
Layer Versus

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

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