scholarly journals Manual for Thin Asphalt Overlays

2020 ◽  
Author(s):  
Lerose Lane ◽  
R. Gary Hicks ◽  
DingXin Cheng ◽  
Erik Updyke
Keyword(s):  
Good Condition ◽  
Technical Information ◽  
Functional Condition ◽  
Pavement Preservation ◽  
Asphalt Overlay ◽  
The 1960S ◽  
Senate Bill 1 ◽  
Local Agencies ◽  
Asphalt Overlays ◽  
Design And Construction

This manual presents best practices on project selection, mix design, and construction to ensure a superior product when constructing thin asphalt overlays. Experience shows these treatments provide excellent performance when placed on pavements in fair to good condition using proper construction techniques. Though sometime referred to by other names, thin asphalt overlays have been widely used for pavement preservation throughout the world for over 50 years. Limited infrastructure funding at the local, state, and federal levels has resulted in greater emphasis on the use of pavement preservation techniques to extend pavement life and reduce maintenance costs. Thin asphalt overlays are one of many preventative maintenance treatments. Thin asphalt overlays are placed directly on existing pavement and can range from 1/2 inch to 1 1/2 inches in thickness. Thin asphalt overlays have proven to be an economical means for maintaining and improving the functional condition of an existing pavement since the 1960s. Specifically, this manual provides guidance for engineers regarding where and when to use thin asphalt overlays including: (1) Types and variations of thin overlays; (2) Materials and the design process; (3) Construction; (4) Quality Assurance; and (5) Troubleshooting. This chapter by chapter guidance enables an Agency’s engineers to design and construct a successful thin asphalt overlay project to completion. This manual is one of four new manuals prepared by the California Pavement Preservation Center (CP2Center) using funding from California Senate Bill 1 (SB-1), passed in April 2017. The other three manuals provide detailed design and construction information for (1) chip seals, (2) slurry surfacing, and (3) Cape seals. The creation of these manuals was a task funded entirely from SB-1 monies for the purpose of disseminating training and technical information on highway pavement preservation to local agencies throughout California.

High-Performance Thin-Lift Overlays with High Reclaimed Asphalt Pavement Content and Warm-Mix Asphalt Technology

2012 ◽  
Vol 2293 (1) ◽  
pp. 18-28 ◽  
Author(s):  
Walaa S. Mogawer ◽  
Alexander J. Austerman ◽  
Robert Kluttz ◽  
Michael Roussel
Keyword(s):  
High Performance ◽  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Asphalt Binders ◽  
Reclaimed Asphalt Pavement ◽  
Moisture Susceptibility ◽  
Reclaimed Asphalt ◽  
Pavement Preservation ◽  
Asphalt Overlay ◽  
Structural Capacity

A high-performance thin asphalt overlay (HPThinOL) is specified as having a thickness of 1 in. or less and is used in applications requiring high levels of rutting and fatigue resistance. HPThinOLs are used as a pavement preservation strategy and are placed on pavements that have remaining structural capacity that is expected to outlive that strategy. Current specifications for HPThinOLs generally call for a polymer-modified asphalt (PMA). However, PMA binders are more expensive than unmodified asphalt binders. This expense, coupled with the higher binder content requirement generally associated with HPThinOL, could lead to an initial higher cost in relation to other pavement preservation strategies. Although the higher initial cost can be offset by incorporating high amounts of reclaimed asphalt pavement (RAP), the use of high amounts of RAP in PMA mixtures might adversely affect the mixture performance (stiffness, cracking, or workability). Warm-mix asphalt (WMA) technology may improve the workability of HPThinOL that incorporates high RAP content and PMA binders. This study evaluated the effect of PMA binders, high RAP content, and WMA technology on the stiffness, resistance to reflective cracking, moisture susceptibility, and workability of HPThinOL mixtures. PMA binders and high RAP content increased the stiffness of HPThinOL significantly; however, the use of WMA technology lowered mixture stiffness and improved workability. PMA may improve the cracking resistance, moisture susceptibility, and rutting resistance of high-RAP HPThinOL mixtures, depending on whether a WMA technology is used.

Report on Archives of the Popular and Revolutionary Republic of Guinea in Conakry

1981 ◽  
Vol 8 ◽  
pp. 333-334
Author(s):  
Martin A. Klein
Keyword(s):  
Classification System ◽  
Original Work ◽  
Good Condition ◽  
Colonial Administration ◽  
Poor Condition ◽  
Republic Of Guinea ◽  
Exposed Point ◽  
Pleasant Surprise ◽  
Set Up ◽  
The 1960S

Before I came to Conakry I had been warned that the archives were in poor condition, had suffered damage from the elements and from the termites, and were not well maintained. One scholar who worked here in the 1960s spoke not only of termite damage but of chickens and goats wandering through. To my pleasant surprise I have found that the archives are fairly extensive, that they are in relatively good condition, and that they are being maintained as well as can be expected. The locale is not an ideal one, though its location on an exposed point of land near the sea makes for pleasant breezes and good cross-ventilation. There is no control of either temperature or humidity in the building. While some dossiers are partially damaged, I have not seen one that is not usable. My biggest problem has been the handwriting of the clerks and administrators who made copies of correspondence in local registers.The original work of organizing the archives was done by Madeira Keita, the R.D.A. leader, who worked here during the early 1950s. The classification system he set up was maintained by Damien d'Almeida, who published a repertoire in 1962. The repertoire is fairly detailed and it notes when a dossier or a register is in poor condition. The classification system is sound, though occasionally one finds documents, reports, and correspondance grouped together in a haphazard manner. The problem was more the sloppy recordkeeping of the colonial administration than the work of the undermanned archivists. In general, I have been to find what I have wanted and the organization has been very useful. The present archivist, Moctar Ba, is competent and seems conscientious.

Dynamics of activity syntaxonomic centres of Russia and processes of their integration

2017 ◽  
pp. 119-124
Author(s):  
B. M. Mirkin ◽  
L. G. Naumova
Keyword(s):  
Far East ◽  
Technical Information ◽  
East Siberia ◽  
Saint Petersburg ◽  
Code Of Phytosociological Nomenclature ◽  
Union Institute ◽  
History Of ◽  
The 1960S ◽  
Number Of Publications

The history of «rooting» and current state of the Braun-Blanquet approach in Russia are discussed. The process began only in the 1960s, when a more favorable climate has developed in Soviet science, and researches showed interest in the following international principles of vegetation classification. However, at that time they used, as a rule, palliative options in which «Russian» criteria (dominants) were combined with «floristic» ones. As a rule, such schemes were not successful and gave rise to imbalances in syntaxonomy. After the year 1981, when the VI All-Union conference on the classification of vegetation was held in Ufa, Soviet geobotany moved to a «strict version» of the Braun-Blanquet approach. However, at that period there were no journals in the USSR that were ready to published papers with phytosociological tables. For this reason, phytocenologists have used the resources of All-Union Institute of scientific and technical information (VINITI), which provided a free-accepted manuscript deposit, published abstracts of these papers in Refereed journal and for a modest fee sent copies to all interested specialists. The data of the deposited papers became a base for the first variant of the Prodromus of vegetation of Russia, which included 72 classes, 148 orders, 309 alliances and 74 suballiances. Since the year 2001, when the journal «Vegetation of Russia» was organized in Saint-Petersburg, both the high professional level of editorial board and the competent reviewers provide the publication of papers in strict accordance with the Braun-Blanquet approach (including the «International code of phytosociological nomenclature»), that greatly stimulated the development of syntaxonomy in Russia. Five syntaxonomic centers (Far East-Siberia, Ufa, Saint-Petersburg, Togliatti, Bryansk) have been formed. The information of their publication activity (see Table) for the periods 2001–2005, 2006–2011 and 2012–2016 years in all centres (in particular in the Far East-Siberia and Ufa) shows the number of publications is constantly increasing. This gives the hope that in the foreseeable future the Russian syntaxonomists will be able to materialize the multi-volume edition «The Vegetation of Russia».

Dynamic Response Analysis of Stress Intensity Factors of Reflective Cracking in Asphalt Overlay Suffer Wheel Load

2011 ◽  
Vol 217-218 ◽  
pp. 187-190
Author(s):  
Bin Yang ◽  
Qin Shou Huang ◽  
Xin Wang Qiu ◽  
Hua Xu
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Dynamic Loads ◽  
Response Analysis ◽  
Reflective Cracking ◽  
Intensity Factors ◽  
Wheel Load ◽  
Asphalt Overlay ◽  
Wheel Loading ◽  
Asphalt Overlays

Partial wheel loading of the existing old cement concrete pavement joint will easily causes shear-type reflective cracking of asphalt overlay, which will cut down the service life of the pavement. This paper conducts an research on the changing rules of stress intensity factors of reflective cracking in asphalt overlay suffer dynamic loads. Choose 3 asphalt overlays with typical reflective cracking extend length of 1cm, 4cm and 8cm to investigate the impacts of parametric variation of vehicle speed, asphalt overlays thickness and modulus and stress absorbing layer on stress intensity factors of reflective cracking in asphalt overlays suffer singe-wheel dynamic loads. Results show that time history curves of dynamic stress intensity factors declines with the increase of structure-layer parameters; the maximum amplitude decreases as time goes on; the larger the structure parameter is, the faster the degradation is; and the vibration levels to gentle in the later half period, but stress intensity factors are not equal to zero in the last period of vibration, which shows that there exists residual stress intensity factors.

scholarly journals Effects of Dissipative Systems on the Seismic Behavior of Irregular Buildings—Two Case Studies

Buildings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 202
Author(s):  
Marco Miani ◽  
Caterina Di Marco ◽  
Giada Frappa ◽  
Margherita Pauletta
Keyword(s):  
Technical Information ◽  
Structural Response ◽  
Torsional Stiffness ◽  
Dissipative Systems ◽  
Seismic Action ◽  
Existing Building ◽  
Heritage Buildings ◽  
Fluid Dampers ◽  
The 1960S ◽  
Energy Dissipation Devices

Conservation of heritage buildings has become a very important issue in many countries, as it is in Italy, where a great number of existing buildings of historical–artistic importance are seismically vulnerable. To improve existing building behavior, researchers focus on the design of retrofit interventions. This paper presents the application of energy dissipation devices in the retrofit of two existing Reinforced Concrete (RC) buildings, both irregular in plan and along their heights, designed for gravitational loads only. These buildings are representative of Italian public housing built in the 1960s and early 1970s. Technical information and mechanical properties of materials are presented, and non-linear analyses are carried out to evaluate the buildings’ behavior under earthquake loads. Many of their structural members do not satisfy the verifications required by the Italian Building Code. Retrofit interventions with buckling-restrained axial dampers in one building and viscous fluid dampers in the other are proposed. The verifications of the retrofitted buildings and the amount of the energy absorbed by the devices with respect to that absorbed by the unretrofitted buildings show the effectiveness of the proposed interventions. Moreover, it is demonstrated that adequate dispositions of the dissipative devices in plan and along the height increase the torsional stiffness of the buildings, improving their structural response under seismic action.

Study of Structural Characteristics of Asphalt Overlays on Airport Pavement with Damaged Load Transfer Efficiency of Joints

2021 ◽  
pp. 036119812110569
Author(s):  
Kaifeng Wang ◽  
Kai Wang ◽  
Yunsheng Zhu ◽  
Yunhan Bao ◽  
Zhou Fang
Keyword(s):  
Shear Stress ◽  
Critical Point ◽  
Load Transfer ◽  
Transfer Efficiency ◽  
Asphalt Overlay ◽  
Airport Pavement ◽  
Low Modulus ◽  
Load Transfer Efficiency ◽  
Absorbing Layer ◽  
Asphalt Overlays

In this paper, the real joint load transfer efficiency of airport pavement is calculated by combining the results of airport pavement deflection detection and ground-penetrating radar detection. Spring elements are used to simulate the actual load transfer efficiency of joints in ABAQUS. The impact of different asphalt overlays on the stress state of the critical point in the pavement is analyzed by the airport cement concrete pavement model. The result shows that adding a thin stress-absorbing layer with fine-graded and low modulus can effectively disperse the load transferred from the asphalt pavement to the cement pavement and the stress concentration at the joint under the asphalt overlay. Compared with airport pavement without a stress-absorbing layer, the tensile stress and shear stress at the critical point in the airport pavement asphalt overlay decreased by 24.62% and 22.49%, respectively. Therefore, the combination of the high-modulus upper layer and low-modulus lower layer can effectively reduce the tensile stress and shear stress at the critical point. In addition, increases in the thickness of the asphalt overlay can effectively improve the stress state at the critical point. When the thickness of the asphalt overlay changed from 13 cm to 21 cm, the maximum tensile and shear stress decreased by 8.82% and 8.92%, respectively. Finally, based on the analysis of the numerical simulation and field test verification, the optimal airport pavement asphalt overlay scheme is proposed.

Finite Element Analysis of Asphalt Overlays on Existing PCC Pavement under Heavy Traffic Loading

2011 ◽  
Vol 361-363 ◽  
pp. 1472-1475
Author(s):  
Jun Min Shen ◽  
Yu Min Zhou ◽  
Xiao Zhang
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Heavy Traffic ◽  
Influence Factors ◽  
Strength Index ◽  
Element Analysis ◽  
Traffic Loading ◽  
Asphalt Overlay ◽  
Soft Interlayer ◽  
Asphalt Overlays

This study models the thermal stresses and load stresses of Xia-Feng expressway asphalt overly on an existing PCC pavement by using finite element method. The sensitiveness of different influence factors on thermal stresses and load stresses are discussed. Research results show that asphalt overlay deflection and load stresses increase with the decreasing of weakening of subgrade strength index λk and when a soft interlayer with low level of spring stiffness is adopted, the thermal stress of asphalt overlay is quite small compared with load stresses.

Development of Canadian asphalt pavement deterioration models to benchmark performance

2003 ◽  
Vol 30 (4) ◽  
pp. 637-643 ◽  
Author(s):  
Chris Raymond ◽  
Susan Tighe ◽  
Ralph Haas ◽  
Leo Rothenburg
Keyword(s):  
Univariate Analysis ◽  
Pavement Performance ◽  
Site Location ◽  
Site Factors ◽  
Asphalt Overlay ◽  
Pavement Roughness ◽  
Pavement Deterioration ◽  
Individual Project ◽  
Asphalt Overlays

The Canadian Long Term Pavement Performance (C-LTPP) study, initiated in 1989, involves 65 sections located at 24 sites constructed with various asphalt overlay rehabilitation treatments. This study investigates the impacts of the various alternative rehabilitation treatments on pavement roughness progression. A series of models are developed for predicting the rate of pavement deterioration occurring for the first 8 years of service. The models examine both within-site factors and between-site factors. Site location is found to be the primary influence on the rate of pavement deterioration. Overlay thickness and the amount of cracking prior to rehabilitation are also determined to influence pavement deterioration at a strong statistical level. Models are provided for benchmarking the performance of pavements across Canada, for comparison with individual project designs, and for estimating the performance of designs with different overlay thickness.Key words: Canadian Long Term Pavement Performance program, roughness, pavement deterioration, site effects, asphalt overlays, benchmark, univariate analysis.

Performance of Waterproofing Membranes to Protect Concrete Bridge Decks

2021 ◽  
pp. 036119812110095
Author(s):  
Matthew A. Haynes ◽  
Erdem Coleri ◽  
Ihsan Obaid
Keyword(s):  
Bridge Decks ◽  
Concrete Bridge ◽  
Heavy Vehicles ◽  
Asphalt Overlay ◽  
Concrete Bridge Decks ◽  
High Bond ◽  
Bond Strengths ◽  
Waterproofing Membrane ◽  
Asphalt Overlays ◽  
Transportation Agencies

The installation of waterproofing membranes on concrete bridge decks is a commonly used strategy to prevent water on the roadway surface from penetrating into the deck and to reduce the load and freeze–thaw related damage to the bridge deck. Typically, an asphalt layer is paved over the waterproofing membrane to prevent damage from heavy vehicles. The early failure of asphalt pavement overlays on concrete bridge decks with waterproofing membranes has been recognized as a significant issue by several transportation agencies. Potential reasons for the failure of the asphalt overlay were thought to be poor adhesion between the waterproofing membrane and the asphalt wearing course, and the material properties of the asphalt layer. By determining the most effective waterproofing methods and strategies, this research will serve to decrease repair and replacement costs, and increase the service life of asphalt overlays on concrete bridge decks. The main goals of this study are to provide the industry and transportation agencies with better insight into the failure mechanisms of asphalt overlays on concrete bridge decks and to establish field and laboratory experiments to evaluate the performance of these overlays. From the results of this study, a poured waterproofing membrane was recommended as an ideal membrane for use on concrete bridge decks because of its ease of installation, complete impermeability, and high bond strengths between the concrete deck, membrane layers, and asphalt overlay.

Sign in / Sign up

Export Citation Format

Share Document