scholarly journals Influence of Gradation on the Mechanical Properties of Aged Hot-Mix Asphalts

Buildings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 632
Author(s):  
Saieth Baudilio Chaves-Pabón ◽  
Hugo Alexander Rondón-Quintana ◽  
Carlos Alfonso Zafra-Mejía
Keyword(s):  
Mechanical Properties ◽  
Cyclic Load ◽  
Stress Condition ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Short Term ◽  
Clear Trend ◽  
Indirect Tensile ◽  
Effects Of Aging

When a hot-mix asphalt (HMA) ages, its mechanical properties, resistance, and durability change. Several studies have been conducted throughout the world to evaluate the effects of aging in HMAs. However, few studies have analyzed the influence of gradation. The main objective of this study was to evaluate the influence of gradation on the mechanical properties of aged HMA mixes. For such purposes, three HMA mixes with different gradations were manufactured (named HMA-10, HMA-19, and HMA-25), which were conditioned in STOA (short-term oven aging) and LTOA (long-term oven aging) by following the guidelines established by the AASHTO R30 specification. Marshall, Indirect Tensile Strength (ITS), resilient modulus, permanent deformation, fatigue (under controlled-stress condition), and Cantabro tests were performed. These tests were carried out to evaluate resistance under monotonic and cyclic load as well as the resistance to moisture damage and abrasion. The best performing mix in the test was HMA-19. There is no clear trend about the influence of gradation over the susceptibility of mixes for aging. This susceptibility changes depending on the test performed and the property measured. Furthermore, in resilient modulus tests, it is observed that the influence of gradation on aging susceptibility changes depending on the test temperature.

Comparison of Coarse Matrix High Binder and Dense-Graded Hot-Mix Asphalt

1997 ◽  
Vol 1590 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Richard P. Izzo ◽  
Joe W. Button ◽  
Maghsoud Tahmoressi
Keyword(s):  
Tensile Strength ◽  
Creep Test ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Moisture Damage ◽  
Static Creep ◽  
Indirect Tensile ◽  
Effects Of Aging ◽  
Static Creep Test

Coarse matrix high binder (CMHB) is a gap-graded hot mix consisting of a large proportion of coarse aggregate with an asphalt binder-filler mastic. CMHB and dense-graded mixtures were compared in terms of their resistance to rutting (permanent deformation), moisture damage, aging, and water permeability. A static creep test was performed to evaluate relative rutting susceptibility. Moisture damage was assessed with the tensile strength ratio (TSR) and a boiling-water test. The effects of aging were evaluated with indirect tensile strength and resilient modulus testing. Penetration and complex shear modulus ( G*) of the recovered, aged asphalt were measured. Permeability was determined with Darcy's Law for flow through saturated, porous media. The static creep test did not indicate that CMHB mixtures were consistently more resistant to rutting in comparison with dense-graded mixtures. CMHB mixtures were found to be more resistant to moisture damage, which was indicated by higher TSR values and less visible stripping than corresponding dense-graded mixtures. The dense-graded mixtures exhibited higher resilient moduli and indirect tensile strengths after short-term and long-term aging. Penetration of binder extracted from aged CMHB mixtures was greater than that from dense-graded mixtures. Binder extracted from aged dense-graded mixtures exhibited higher G* values. The permeability of CMHB mixtures was greater than that of the dense-graded mixtures with comparable air voids.

scholarly journals MECHANICAL PERFORMANCE OF ASPHALT MIXTURE CONTAINING CUP LUMP RUBBER

2019 ◽  
Vol 81 (6) ◽  
Author(s):  
Norfazira Mohd Azahar ◽  
Norhidayah Abdul Hassan ◽  
Ramadhansyah Putra Jaya ◽  
Hasanan Md. Nor ◽  
Mohd Khairul Idham Mohd Satar ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Modified Asphalt ◽  
Dynamic Creep ◽  
Aging Conditions ◽  
Public Work Department ◽  
Indirect Tensile

The use of cup lump rubber as an additive in asphalt binder has recently become the main interest of the paving industry. The innovation helps to increase the natural rubber consumption and stabilize the rubber price. This study evaluates the mechanical performance of cup lump rubber modified asphalt (CMA) mixture in terms of resilient modulus, dynamic creep and indirect tensile strength under aging conditions. The CMA mixture was prepared using dense-graded Marshall-designed mix and the observed behavior was compared with that of conventional mixture. From the results, both mixtures passed the volumetric properties as accordance to Malaysian Public Work Department (PWD) specification. The addition of cup lump rubber provides better resistance against permanent deformation through the enhanced properties of resilient modulus and dynamic creep. Furthermore, the resilient modulus of CMA mixture performed better under aging conditions.  

scholarly journals Improvement of Back and Leg Pain after Lumbar Spinal Decompression without Fusion

2018 ◽  
Vol 80 (02) ◽  
pp. 081-087
Author(s):  
Nicola Bongartz ◽  
Christian Blume ◽  
Hans Clusmann ◽  
Christian Müller ◽  
Matthias Geiger
Keyword(s):  
Back Pain ◽  
Spinal Stenosis ◽  
Lumbar Spinal Stenosis ◽  
Leg Pain ◽  
Short Term ◽  
Clear Trend ◽  
Long Term Follow Up ◽  
Lumbar Spinal

Background To evaluate whether decompression in lumbar spinal stenosis without fusion leads to sufficient improvement of back pain and leg pain and whether re-decompression alone is sufficient for recurrent lumbar spinal stenosis for patients without signs of instability. Material and Methods A successive series of 102 patients with lumbar spinal stenosis (with and without previous lumbar surgery) were treated with decompression alone during a 3-year period. Data on pre- and postoperative back pain and leg pain (numerical rating scale [NRS] scale) were retrospectively collected from questionnaires with a return rate of 65% (n = 66). The complete cohort as well as patients with first-time surgery and re-decompression were analyzed separately. Patients were dichotomized to short-term follow-up (< 100 weeks) and long-term follow-up (> 100 weeks) postsurgery. Results Overall, both back pain (NRS 4.59 postoperative versus 7.89 preoperative; p < 0.0001) and leg pain (NRS 4.09 versus 6.75; p < 0.0001) improved postoperatively. The short-term follow-up subgroup (50%, n = 33) showed a significant reduction in back pain (NRS 4.0 versus 6.88; p < 0.0001) and leg pain (NRS 2.49 versus 6.91: p < 0.0001). Similar results could be observed for the long-term follow-up subgroup (50%, n = 33) with significantly less back pain (NRS 3.94 versus 7.0; p < 0.0001) and leg pain (visual analog scale 3.14 versus 5.39; p < 0.002) postoperatively. Patients with previous decompression surgery benefit significantly regarding back pain (NRS 4.82 versus 7.65; p < 0.0024), especially in the long-term follow-up subgroup (NRS 4.75 versus 7.67; p < 0.0148). There was also a clear trend in favor of leg pain in patients with previous surgery; however, it was not significant. Conclusions Decompression of lumbar spinal stenosis without fusion led to a significant and similar reduction of back pain and leg pain in a short-term and a long-term follow-up group. Patients without previous surgery benefited significantly better, whereas patients with previous decompression benefited regarding back pain, especially for long-term follow-up with a clear trend in favor of leg pain.

Materials for Well Integrity: Characterization of Short-Term Mechanical Properties

2020 ◽  
Author(s):  
Mohammadreza Kamali ◽  
Mahmoud Khalifeh ◽  
Arild Saasen ◽  
Laurent Delabroy
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strength Reduction ◽  
Indirect Tensile Strength ◽  
Short Term ◽  
Indirect Tensile ◽  
Expansive Cement

Abstract Integrated zonal isolation is well-known as a key parameter for safe drilling operation and well completion of oil and gas wells. An extensive research on alternative materials has been conducted in the past concerning primary cementing, overcoming annular leaks, and permanent well abandonment. The present article focuses on geopolymers, expansive cement, pozzolan based sealant and thermosetting resins. The viscous behavior and the pumpability of the different materials have been investigated and benchmarked with the properties of neat class G Portland cement. The current study includes short-term mechanical properties of the above-mentioned materials. These properties include compressive strength development, Young’s modulus, indirect tensile strength, and sonic strength. The tests are performed in accordance with API 10B-2 and ASTM D3967-16 for all the materials for 1, 3, 5, and 7-day of curing at 90°C and elevated (172 bar) and atmospheric pressures. Our results show a mixed behavior from the materials. According to uniaxial compressive test results, all the candidate barrier materials developed strength during the considered period; however, the geopolymer and pozzolanic-based mixture did not develop early strength. The expansive cement showed an acceptable early compressive strength, but strength reduction was noticed after some time. The strength reduction of expansive cement was also observed for the indirect tensile strength. All the materials become stiffer overtime as they made more strength. For the neat class G cement and expansive cement, the Young’s modulus showed a minimum after 5 days, but it was increased.

Design properties of laterally loaded nailed or bolted wood joints

1988 ◽  
Vol 15 (4) ◽  
pp. 633-643 ◽  
Author(s):  
Ian Smith ◽  
Luke R. J. Whale ◽  
Colin Anderson ◽  
Barry O. Hilson ◽  
Peter D. Rodd
Keyword(s):  
Mechanical Properties ◽  
Key Words ◽  
Bolted Joints ◽  
Design Codes ◽  
Short Term ◽  
Limit States ◽  
Design Solutions ◽  
Reliable Knowledge ◽  
Laterally Loaded

This paper summarizes the output from a long-term project commenced in 1980 with the objective of providing reliable knowledge of the mechanical properties of nailed or bolted joints subjected to short-term lateral loadings. Motivation was the development on an international basis of probability-based partial coefficients limit states design codes for structural timberwork. Comparisons are presented between design solutions produced by applying this research and those by the use of contemporary "soft conversion" international partial coefficients limit states design codes that were calibrated from previously available data. Differences relate primarily to design of bolted joints. It is shown that there is an established acceptance in Canada of the approach adopted. Key words: wood, joints, nails, bolts, design.

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%.

scholarly journals The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6076
Author(s):  
Ladislav Falat ◽  
Lucia Čiripová ◽  
Viera Homolová ◽  
Miroslav Džupon ◽  
Róbert Džunda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Toughness ◽  
Room Temperature ◽  
Laves Phase ◽  
Short Term ◽  
Boiler Steel ◽  
P92 Steel ◽  
The Impact

In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

scholarly journals Mechanical performance of HMA-2 modified with purified and unpurified carbon nanotubes and nanofibers

2017 ◽  
Vol 37 (2) ◽  
pp. 99-106
Author(s):  
Mario Rodrigo Rubio ◽  
Duván Julián Martínez ◽  
Carlos Enrique Daza ◽  
Fredy Alberto Reyes
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Mechanical Performance ◽  
Resilient Modulus ◽  
Type Ii ◽  
Dynamic Characterization ◽  
Traffic Loads ◽  
Nickel Copper

The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2) modified with carbon nanotubes and carbon nanofibers (CNTF). CNTF were made by means the Catalytic Vapor Deposition (CVD) technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl) catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1) HMA-2 modified with purified CNTF; 2) HMA-2 modified with non-purified CNTF and, 3) a Conventional HMA-2 (control). Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr) and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatiguerelated issues and improve the long-term durability of flexible pavements.

Study of the Influence of the Chemical Resistance of Polyphenylenesulphone from Radel on Mechanical Properties

2021 ◽  
Vol 899 ◽  
pp. 245-252
Author(s):  
Elena V. Rzhevskaya ◽  
Vladlena V. Davydova ◽  
Igor V. Dolbin
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Chemical Resistance ◽  
Short Term ◽  
Chemical Reagents

The paper presents the results of a study of the chemical resistance and mechanical properties of polyphenylene sulfone manufactured by Solvay, Radel brand, obtained by injection molding. Chemical resistance was investigated in short-term tests (24 hours duration), standard (7 days) and long-term (16 weeks). The mechanics of PPSU samples after exposure to chemical reagents is presented. It was revealed in what chemical environments and how much the mechanical properties of polyphenylene sulfone are preserved.

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