scholarly journals A New-Type Semi-Rigid Base Layer Structure for Long Service Life Pavement

2021 ◽  
Vol 8 (3) ◽  
pp. 140-145
Author(s):  
Bowen Tian ◽  
Chuanfeng Zheng ◽  
Haisong Luo ◽  
Junpeng Xun
Keyword(s):  
Service Life ◽  
Layer Structure ◽  
Base Layer ◽  
Rigid Base ◽  
Vertical Strain ◽  
Transverse Tensile ◽  
New Type ◽  
Theoretical Evidence ◽  
Different Thickness

Targeting at the problem of pavement cracking under long-term load, this study developed a new-type semi-rigid base layer structure based on the CGC (cement stabilized macadam - graded broken stone - cement stabilized macadam) combinations, and used ANSYS to simulate this proposed structure under conditions of different modulus combinations, deflection under different thickness, different vertical strain values on the top surface of roadbed, and different transverse tensile stress values of bottom base layer. The simulation results indicate that, the various mechanical properties of the proposed new structure can well meet the specifications, and the time of crack generation has been slowed down; the use of graded broken stone in the proposed structure has achieved both the purposes of saving construction cost and reducing construction difficulty. By reasonably controlling the CGC structure and modulus, this study has successfully suppressed the generation of reflection cracks, which can provide good theoretical evidence for prolonging the service life of semi-rigid base layer pavement.

scholarly journals Effect of Oxidative Aging on the Engineering Properties of DGAMs

2018 ◽  
Vol 7 (4) ◽  
pp. 50
Author(s):  
Al-Hadidy A.I. ◽  
Abdullah M. Rashed
Keyword(s):  
Service Life ◽  
Flexural Strength ◽  
Permanent Deformation ◽  
Engineering Properties ◽  
Base Layer ◽  
Short Term ◽  
Asphalt Cement ◽  
Oxidative Aging ◽  
Short And Long Term

Short and long term aging were conducted on the dense graded asphalt mixtures (DGAMs) containing 40-50 penetration grade asphalt cement binders. The short term oven aging (STOA) was conducted on loose mixtures at temperature of 135 °C for four hours and at temperature of 154 °C for two hours, whereas, the long term oven aging (LTOA) was conducted at temperature of 85 °C and at two periods of time between four and eight days. Marshall properties, tensile and compressive strength at 25 and 60°C, flexural strength at 0 and -10°C, cohesion at 60°C, tensile strength ratio, and index of retained strength were carried out on unaged and aged DGAM. A mechanistic-empirical design approach using BISAR program was adopted for estimating the improvement in service life of the pavement or reduction in thickness of DGAM and base layer for the same service life due to the aging of DGAM. The results showed that the STOA and LTOA: (1) increases resistance of DGAM against permanent deformation, stripping, and flexural strength; (2) increases traffic benefit ratio between 10 and 20%; (3) reduces the thickness of the surface layer between 8 and 14%; and (4) the base thickness reduces between 35% and 57%.

Influence on the Stress of Pavement with Crack in Base from Flexible Transition Layer under Dynamic Loading

2012 ◽  
Vol 602-604 ◽  
pp. 2189-2192
Author(s):  
Shuai Tu ◽  
Ai Min Sha
Keyword(s):  
Surface Layer ◽  
Stress Concentration ◽  
Service Life ◽  
Transition Layer ◽  
Base Layer ◽  
Rigid Base ◽  
Limited Size ◽  
The Road ◽  
Stress Mode ◽  
Load Analysis

After cracks appear in the semi-rigid base layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the cracks become stress concentration areas. Based on the practical tire contact pressure and contact area, this paper establishes the C3D8R model by ABAQUS, to calculate and analyse the influence on the base cracks extension from graded gravel transition layer under half-sinusoid load. Analysis shows that the graded gravel has excellent stress dissipation ability. Whether there are cracks in the base, the graded gravel transition layer between asphalt surface layer and semi-rigid base layer could greatly reduce the tensile stresses in the bottom of semi-rigid base and subbase layers, improve the road bearing level, delay and avoid the cracks extension to deep road and prolong the road service life.

The Composite Asphalt Pavement Structure Serrice Life Analysis which Setting the Graded Gravel between the Asphalt Surface Layer and the Semi-Rigid Base Layer

2012 ◽  
Vol 446-449 ◽  
pp. 2523-2527
Author(s):  
Gui Mei Shi ◽  
Dong Guo Li
Keyword(s):  
Surface Layer ◽  
Service Life ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Base Layer ◽  
Rigid Base ◽  
Contact State ◽  
The Road ◽  
Pavement Structure ◽  
Three Dimensional Finite Element

In this article, the three-dimensional finite element method was used to analyse the composite base asphalt pavement structure life, which setting the graded gravel layer between the asphalt surface layer and the semi-rigid base layer. The main effect considering on the service life were the face layer thickness, the graded gravel thickness ,the contact state and so on, and compared the compound base with typical semi-rigid base the service life of the asphalt pavement . The analysis shown that the road surface contact state was the biggest influence to the service life. When using reasonable pavement structure combination, composite base asphalt pavement generally wouldn't produce the service life of the decline .

Basalt Reinforced Plastics: Some Operating Properties

2007 ◽  
Vol 561-565 ◽  
pp. 671-674 ◽  
Author(s):  
G.S. Abashidze ◽  
Fernand D.S. Marquis ◽  
N.M. Chikhradze
Keyword(s):  
Composite Materials ◽  
Service Life ◽  
Caustic Soda ◽  
Polyester Resin ◽  
Basalt Fiber ◽  
Corrosive Media ◽  
Operating Properties ◽  
Reinforced Plastics ◽  
New Type

Results of the investigation of composite materials of new type, based on basalt fiber and polyester resin, are presented, in particular, a long-term resistance of the material in corrosive media: in caustic soda as well as in sulphuric and nitric acids of 1% concentration has been estimated. The service life of given composite is recommended in above-mentioned media.

scholarly journals Current and New Approaches to Predict the Deflections of One-Way Flexural Members with a Focus on Composite Steel Deck Slabs Voided by Circular Tubes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 421
Author(s):  
Chang-Hwan Lee ◽  
Iman Mansouri ◽  
Jaehoon Bae ◽  
Jaeho Ryu
Keyword(s):  
Structural Function ◽  
Flexural Members ◽  
Long Span ◽  
Deck Slabs ◽  
New Type ◽  
New Perspective ◽  
Flexural Tests ◽  
Prediction Approach ◽  
Steel Deck

A new type of composite voided slab, the TUBEDECK (TD), which utilizes the structural function of profiled steel decks, has recently been proposed. Previous studies have confirmed that the flexural strength of TD slabs can be calculated based on the full composite contribution of the steel deck, but for long-span flexural members, the deflection serviceability requirement is often dominant. Herein, we derived a novel deflection prediction approach using the results of flexural tests on slab specimens, focusing on TD slabs. First, deflection prediction based on modifications of the current code was proposed. Results revealed that TD slabs exhibited smaller long-term deflections and at least 10% longer maximum span lengths than solid slabs, indicating their greater efficiency. Second, a novel rational method was derived for predicting deflections without computing the effective moment of inertia. The ultimate deflections predicted by the proposed method correlated closely with the deflection under maximum bending moments. To calculate immediate deflections, variation functions for the concrete strain at the extreme compression fiber and neutral axis depth were assumed with predictions in good agreement with experiments. The proposed procedure has important implications in highlighting a new perspective on the deflection prediction of reinforced concrete and composite flexural members.

scholarly journals A Novel Highly Durable Carbon/Silver/Silver Chloride Composite Electrode for High-Definition Transcranial Direct Current Stimulation

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1962
Author(s):  
Lingjun Li ◽  
Guangli Li ◽  
Yuliang Cao ◽  
Yvonne Yanwen Duan
Keyword(s):  
Service Life ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Silver Chloride ◽  
Cycling Performance ◽  
High Definition ◽  
Silver Silver ◽  
Sintered Ag ◽  
Silver Silver Chloride

High-definition transcranial direct current stimulation (HD-tDCS) is a promising non-invasive neuromodulation technique, which has been widely used in the clinical intervention and treatment of neurological or psychiatric disorders. Sintered Ag/AgCl electrode has become a preferred candidate for HD-tDCS, but its service life is very short, especially for long-term anodal stimulation. To address this issue, a novel highly durable conductive carbon/silver/silver chloride composite (C/Ag/AgCl) electrode was fabricated by a facile cold rolling method. The important parameters were systematically optimized, including the conductive enhancer, the particle size of Ag powder, the C:Ag:PTFE ratio, the saline concentration, and the active substance loading. The CNT/Ag/AgCl-721 electrode demonstrated excellent specific capacity and cycling performance. Both constant current anodal polarization and simulated tDCS measurement demonstrated that the service life of the CNT/Ag/AgCl-721 electrodes was 15-16 times of that of sintered Ag/AgCl electrodes. The much longer service life can be attributed to the formation of the three-dimensional interpenetrating conductive network with CNT doping, which can maintain a good conductivity and cycling performance even if excessive non-conductive AgCl is accumulated on the surface during long-term anodal stimulation. Considering their low cost, long service life, and good skin tolerance, the proposed CNT/Ag/AgCl electrodes have shown promising application prospects in HD-tDCS, especially for daily life scenarios.

Mechanical Response Analysis of the Composite Asphalt Pavement

2014 ◽  
Vol 1023 ◽  
pp. 28-31
Author(s):  
Li Min Li
Keyword(s):  
Service Life ◽  
Mechanical Response ◽  
Asphalt Pavement ◽  
Road Construction ◽  
Pavement Design ◽  
Rigid Base ◽  
Response Analysis ◽  
Early Failure ◽  
Short Service Life ◽  
Design Software

With the constant increasing of traffic flow and axle load, the early failure of semi-rigid base asphalt pavement is increasingly serious in China. The bad durability and short service life of pavement have become main obstacles in road construction development. Based on the experience of successful application, the early failure of semi-rigid base asphalt pavement is solved, and the service life of pavement is increased by using of the composite asphalt pavement. To solve the design problem of the composite asphalt pavement , its mechanical properties influence results of are obtained by the factors, such as shear strain, shear stress, compression strain on top of subgrade, etc, by a lot of calculation using Shell pavement design software. These provide theoretical basis for durable asphalt pavement design based on rut-resistance property.

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