Stiffness Evolution of Granular Materials Stabilized with Foamed Bitumen and Cement

2013 ◽  
Vol 2363 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Felipe Halles ◽  
Guillermo Thenoux ◽  
Álvaro González
Keyword(s):  
Stress Level ◽  
Reduction Rate ◽  
Curing Process ◽  
Initial Stiffness ◽  
Stabilizing Agents ◽  
A Value ◽  
Tensile Fatigue ◽  
Analysis Of Results ◽  
Indirect Tensile ◽  
Foamed Bitumen

From the literature, it is possible to find two trends regarding the stiffness evolution of foamed bitumen stabilized–recycled mixtures. The first trend indicates that once the foamed bitumen mix reaches a constant value because of the curing process, the stiffness decreases with time because of load cycles. The second trend indicates that stiffness remains constant after the curing process. In this research, the stiffness evolution of foamed bitumen mixes stabilized with different bitumen and cement contents was studied. The stiffness was measured by using the indirect tensile fatigue test. Results indicated that once the foamed bitumen mix reached a constant value because of the curing process, stiffness decreased or remained constant depending on the stress level applied to the foamed bitumen layer. If the stress level is lower than a specific value, the stiffness of the mix will remain constant at a value extremely close to the initial stiffness. If the stress level is greater than a specific value, the stiffness of the mix will decrease gradually. In addition, the reduction rate of the stiffness will be greater with higher stress level. The analysis of results from mixes with different bitumen and cement contents allows identification of the effect of both stabilizing agents in the long-term stiffness evolution.

scholarly journals Analysis of stiffness and fatigue resistance of cold recycled asphalt mixtures manufactured with foamed bitumen for their application to airfield pavement design

2017 ◽  
Vol 7 (080) ◽  
pp. 127 ◽  
Author(s):  
H. I. Lacalle-Jiménez ◽  
J. P. Edwards ◽  
N. H. Thom
Keyword(s):  
Fatigue Tests ◽  
Pavement Design ◽  
Raw Material ◽  
Control Mode ◽  
Recycled Asphalt ◽  
Stiffness Modulus ◽  
Reclaimed Asphalt ◽  
Tensile Fatigue ◽  
Indirect Tensile ◽  
Foamed Bitumen

Cold recycled bound materials (CRBMs) provide an economic and environmental advantage for pavements since they decrease energy and raw material consumption. However, design methods for airfield pavements do not include key CRBM properties. In this paper an empirical-mechanistic method is used to study airfield pavement design with CRBM in order to develop design guidance. The aim of the paper is to obtain the inputs related to material properties needed for use in this method. For this purpose, CRBM containing reclaimed asphalt, with fly ash, cement and foamed bitumen as stabilising agents, was characterised. The methodology included indirect tensile stiffness modulus (ITSM) and indirect tensile fatigue tests (ITFT) in strain control mode. The inputs needed for a pavement design analysis with CRBM were then obtained. The results showed the importance of further study on CRBM fatigue to understand the behaviour of these mixes under cyclic loading.

Effect of operating parameters on functional fatigue characteristics of an Ni-Ti shape memory alloy on partial thermomechanical cycling

2022 ◽  
pp. 1045389X2110722
Author(s):  
Swaminathan Ganesan ◽  
Sampath Vedamanickam
Keyword(s):  
Yield Strength ◽  
Applied Stress ◽  
Stress Level ◽  
Crack Nucleation ◽  
Maximum Temperature ◽  
Thermomechanical Cycling ◽  
Permanent Strain ◽  
A Value ◽  
The Stability ◽  
Cycle Temperature

In this study, the influence of upper cycle temperature (maximum temperature in a cycle) and the magnitude of applied stress on the functional properties of an SMA during partial thermomechanical cycling has been studied. A near-equiatomic NiTi SMA was chosen and tested under different upper cycle temperatures (between martensite finish (Mf) and austenite finish (Af) temperatures) and stress level (below and above the yield strength of the martensite). The upper cycle temperature was varied by controlling the magnitude of the current supply. The results show that a raise in the upper cycle temperature causes the permanent strain to increase and also lowers the stability. However, decreasing the stress imposed to a value lower than the yield strength of the martensite improves cyclic stability. The upper cycle temperature was found to influence the crack nucleation, whereas the applied stress level the crack propagation during partial thermomechanical cycling of SMAs. Therefore, decreasing the upper cycle temperature as well as the magnitude of stress applied to lower than the yield stress of martensite have been found to be suitable strategies for increasing the lifespan of SMA-based actuators during partial thermomechanical cycling.

scholarly journals Fatigue Resistance Characterization of Warm Asphalt Rubber by Multiple Approaches

2018 ◽  
Vol 8 (9) ◽  
pp. 1495 ◽  
Author(s):  
Jiangmiao Yu ◽  
Xianshu Yu ◽  
Zheming Gao ◽  
Feng Guo ◽  
Duanyi Wang ◽  
...  
Keyword(s):  
Fatigue Test ◽  
Fatigue Resistance ◽  
Crumb Rubber ◽  
Waste Recycling ◽  
Fatigue Performance ◽  
Four Point Bending ◽  
Asphalt Rubber ◽  
Shear Fatigue ◽  
Tensile Fatigue ◽  
Indirect Tensile

Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR binder and mixtures is very limited. This paper applies five fatigue analysis approaches to evaluate the fatigue life of WAR samples with three different warm mix asphalt (WMA) additives. The conventional G*sinδ, linear amplitude sweep (LAS), indirect tensile fatigue test (ITFT), and four-point bending beam (4PB) test were conducted based on available standards. In addition, a novel shear fatigue test was performed on WAR mortars. Test results indicated that the incorporation of crumb rubber has a significantly positive effect on fatigue resistance. WAR with chemical and foaming additives exhibited a poorer performance than asphalt rubber (AR), but their fatigue performance was still greatly superior to the non-rubberized samples. Finally, LAS as well as mortar shear fatigue and 4PB tests provided the same prediction of fatigue resistance, while the results of G*sinδ and the ITFT were inconsistent. It is recommended to use LAS, the mortar shear fatigue test, and the 4PB test for the fatigue resistance evaluation of rubberized specimens. The validation of the findings with more materials and field performances is recommended.

Fatigue Characteristics of Open-End Thick-Walled Cylinders Under Cyclic Internal Pressure

1963 ◽  
Vol 85 (4) ◽  
pp. 555-565 ◽  
Author(s):  
T. E. Davidson ◽  
R. Eisenstadt ◽  
A. N. Reiner
Keyword(s):  
Fatigue Crack ◽  
Internal Pressure ◽  
Stress Level ◽  
Cyclic Stress ◽  
Diameter Ratio ◽  
Tensile Fatigue ◽  
Stress Levels ◽  
Fatigue Characteristics ◽  
Using Data ◽  
Rate Of Improvement

Thick-walled cylinder fatigue data due to cyclic internal pressure for open-end cylinders in the range of 103 to 105 cycles to failure and having a diameter ratio of 1.4 to 2.0 at a nominal yield strength of 160,000 pounds per square inch is presented. Discussed and also presented are the effects of autofrettage on the fatigue characteristics of thick-walled cylinders. Autofrettage substantially enhances fatigue characteristics at stress levels below the corresponding overstrain pressure, the degree of improvement increasing the decreasing stress levels. The rate of improvement in fatigue characteristics increases significantly with diameter ratio in autofrettaged cylinders up to a diameter ratio of 1.8–2.0 and to a much smaller degree in the nonautofrettaged condition. The rate of improvement of fatigue characteristics above 2.0 is the same for both the autofrettaged and nonautofrettaged cases. It is shown that thermal treatment of 675 F for 6 hours after autofrettage does not affect fatigue characteristics and that there is a correlation between the cyclic-stress level and the area and depth of the fatigue crack to the point of ductile rupture. The depth of the fatigue crack decreases with increasing cyclic-stress level. A means for using data from a unidirectional tensile fatigue test to predict the fatigue characteristics of thick-walled cylinders is discussed.

scholarly journals Application of the foamed bitumen and bitumen emulsion to the road base mixes in the deep cold recycling technology

2016 ◽  
Vol 11 (4) ◽  
pp. 291-301 ◽  
Author(s):  
Marek Iwański ◽  
Anna Chomicz-Kowalska
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Base Layer ◽  
The Road ◽  
Road Base ◽  
Bitumen Emulsion ◽  
Recycling Technology ◽  
Indirect Tensile ◽  
Foamed Bitumen ◽  
Cold Recycling

This paper presents findings of a study concerning the influence of binder type on the mechanical properties of road base in the cold recycling technology. The principal aim of this investigation was to evaluate the mixes in scope of susceptibility to moisture and low-temperatures. In the comparative research foamed bitumen and bitumen emulsion were used in four different concentrations (2.0%, 2.5%, 3.0%, 3.5%). The materials used in the study were reclaimed from an existing road construction layers: reclaimed aggregate from the road base and reclaimed asphalt pavement obtained by milling the surface and binder course. Portland cement in 2.0% concentration was used as a hydraulic binder. The evaluated parameters were: indirect tensile strengths, tensile strength retained and indirect tensile stiffness modulus at 25 °C. These tests were complemented by an evaluation of susceptibility to moisture and frost according to modified procedures implemented by American researchers: Tunnicliff, Root and Lottman. Moreover, tests for low-temperature cracking were conducted according to Finnish standard. The investigations showed that the use of foamed bitumen for road base layer produced in the cold recycling technology results in better mechanical properties and resistance to moisture and frost compared to using bitumen emulsion. The use of 2.5% of foamed bitumen and 2.0% of Portland cement in the recycled road base allowed to meet the established criteria.

scholarly journals Laboratory Evaluation of Gradation Improvement of Marginal Materials for Foamed Bitumen Stabilisation

2020 ◽  
Vol 10 (12) ◽  
pp. 4224
Author(s):  
Greg White ◽  
Roberto Espinosa
Keyword(s):  
Granular Material ◽  
Effective Treatment ◽  
Granular Materials ◽  
Laboratory Evaluation ◽  
Variable Effect ◽  
Construction Specifications ◽  
Average Modulus ◽  
Indirect Tensile ◽  
Foamed Bitumen ◽  
Pavement Construction

Foamed bitumen stabilisation is an attractive technology for increasing the use of marginal materials in pavement construction and rehabilitation. However, by their very nature, marginal materials do not meet the prescriptive requirements of many standard specifications. Consequently, performance-related evaluation is required. For foamed bitumen stabilised marginal materials, the cured and saturated moduli are common performance-related parameters that are also used for characterisation during structural pavement design. In this research, the indirect tensile moduli of three foamed bitumen stabilised marginal granular materials were compared to the modulus of a standard or premium material, in both cured and saturated conditions, after 3, 7 and 14 days of accelerated laboratory curing. The results indicated that the magnitude of granular material marginality was not related to the stabilised material modulus. Furthermore, the gradations of the two most marginal materials were improved by blending with another granular material and the improved marginal materials were also stabilised and tested. The gradation improvement had a variable effect on the stabilised material modulus, with the average modulus increasing by more than 20%. The modulus increase associated with the gradation improvement was related to the basis and magnitude of granular material marginality, with the saturated modulus of the most plastic marginal material increasing by the greater amount after improvement. It was concluded that foamed bitumen stabilisation is a particularly effective treatment for marginal granular materials. Furthermore, when used in combination with gradation improvement, the resulting foamed bitumen stabilised material can perform similarly to standard materials, based on cured and soaked modulus values. However, to allow the use of foamed bitumen stabilised marginal materials in pavement construction, specifications must be more performance-related and the current limits on plasticity and gradation must be relaxed.

scholarly journals Obtaining nitrite from vegetables sources by fermentative process using nitrate-reducing bacteria Sthaphylococcus carnosus and S. xylosus

DYNA ◽  
2019 ◽  
Vol 86 (210) ◽  
pp. 254-261 ◽  
Author(s):  
Diego Alonso Restrepo Molina ◽  
María Carolina Rodríguez Daza ◽  
Mario Evelio Arias Zabala
Keyword(s):  
Consumer Preferences ◽  
Reductase Activity ◽  
Reduction Rate ◽  
Meat Products ◽  
Important Place ◽  
Cured Meats ◽  
A Value ◽  
Oxygen Condition ◽  
Reducing Bacteria ◽  
Nitrate Reducing Bacteria

Sodium nitrate is an essential food additive widely used in cured meats. The increased unfavorable perceptions about chemicals in foods and their repercussions on health have positioned the nitrite as undesirable compound in meat products. Natural and organic ingredients have taken an important place within the consumer preferences. Here, obtaining nitrite from natural source was achieved using nitrate-reducing bacteria Staphylococcus carnosus and S. xylosus. The strains pre-incubation into the celery-based medium allowed the stimulation of nitrate reductase activity. The increased values of substrate, the oxygen condition and pH influenced the nitrite generation significantly (p<0.05). The reduction rate from nitrate to nitrite was 50.85%, with a value 320.2 mg L-1 nitrite for 4h. This method presents characteristics comparable to those traditionally applied in the generation of conventional sodium nitrite and lead to the food industry to take advantage of fermentation processes to supply needs in meats and supplementary food products.

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