scholarly journals Rheological Evaluation of Modified Bitumen by EVA and Crumb Rubber Using RSM Optimization

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Mohamad H. Dehnad ◽  
Behrouz Damyar ◽  
Hossein Z. Farahani
Keyword(s):  
Low Temperatures ◽  
Ethylene Vinyl Acetate ◽  
Crumb Rubber ◽  
Test Results ◽  
Modified Bitumen ◽  
Rsm Optimization ◽  
Different Temperatures ◽  
Creep Stiffness ◽  
Optimal Values ◽  
High And Low Temperatures

In the present study, ethylene-vinyl acetate (EVA) and crumb rubber (CR) were used as bitumen modifiers. The experiment was designed by response surface methodology (RSM) at different levels of modifier additives based on the central composite design (CCD). Next, the Superpave protocol was followed to evaluate the modified bitumen performance at different temperatures compared with the unmodified bitumen. In this regard, to evaluate at high temperatures, a dynamic shear rheometer (DSR) test was performed, and G ∗ /sinδ index was examined on bitumen samples after aging. Besides, the bending beam rheometer (BBR) test was performed to evaluate the low-temperature behaviour of the modified bitumen according to the SHRP standard based on the creep stiffness and creep rate. The optimal combination of additives was evaluated using RSM and analysis of statistical values to improve the performance properties of bitumen at high and low temperatures. Moreover, based on the DSR and BBR test results, 5.6% of EVA and 3.9% of CR were selected as the optimal values for the modified bitumen behaviour at the high and low temperatures of the mixture.

The effect of temperature on the oxygen consumption of isolated human umbilical arteries

1970 ◽  
Vol 48 (6) ◽  
pp. 377-381 ◽  
Author(s):  
Carol Colthart ◽  
Margot R. Roach
Keyword(s):  
Oxygen Consumption ◽  
Low Temperatures ◽  
Arrhenius Plot ◽  
Post Partum ◽  
Effect Of Temperature ◽  
Metabolic Processes ◽  
Different Temperatures ◽  
High And Low Temperatures ◽  
Umbilical Arteries

The oxygen consumption [Formula: see text] of isolated segments of 40 human umbilical arteries was measured at different temperatures from 5 °C to 37 °C with a modified Fenn microrespirometer. The values varied from 8 μl/g per h at 8 °C to 70 μl/g per h at 37 °C. The Arrhenius plot was nonlinear, and the Q10 varied from 0.11 (30–40 °C) to 1.8 (20–30 °C) and 7.1 (10–20 °C). This suggests that the metabolic processes may be different at high and low temperatures. The results were consistent for at least 5 h post partum, and did not seem to vary from one segment of the cord to another.

scholarly journals Determination of Construction Temperatures of Crumb Rubber Modified Bitumen Mixture Based on CRMB Mastic

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3851 ◽  
Author(s):  
Yanan Li ◽  
Yuchao Lyu ◽  
Meng Xu ◽  
Liang Fan ◽  
Yuzhen Zhang
Keyword(s):  
Direct Relationship ◽  
Crumb Rubber ◽  
Test Results ◽  
Modified Bitumen ◽  
Rubber Powder ◽  
Pollution Problem ◽  
Mineral Powder ◽  
Pavement Construction ◽  
Air Void

Crumb rubber modified bitumen (CRMB) has been widely used in pavement construction and provides an effective way to recycle waste tires and helps alleviate the “black pollution” problem. There are no current specifications regarding the appropriate mixing and compaction temperatures of the CRMB mixture. There is a direct relationship between the mixing and the compaction temperatures of the CRMB mixture and the viscosity of the CRMB mastic. In this study, we first prepared CRMB using crumb rubber powder and penetration grade 70 neat bitumen, then prepared the CRMB mastic using CRMB and fillers (limestone mineral powder and cement). Finally, we used the CRMB mastic and aggregate to make mixture specimens. The best air void of the specimens was subsequently used to demarcate the viscosity of the CRMB mastic, and the construction temperatures (including the mixing temperature and the compaction temperature) were calculated based on the viscosity of the CRMB mastic from the viscosity–temperature curves. Test results indicated that the best viscosity of the CRMB mastic was 2.7 ± 0.2 Pa·s and 3.9 ± 0.3 Pa·s that corresponded to the mixing and compaction temperatures, respectively.

scholarly journals The influence of high and low temperatures on the impact properties of glass-epoxy composites

2007 ◽  
Vol 72 (7) ◽  
pp. 713-722 ◽  
Author(s):  
Slavisa Putic ◽  
Marina Stamenovic ◽  
Branislav Bajceta ◽  
Predrag Stajcic ◽  
Srdjan Bosnjak
Keyword(s):  
Low Temperatures ◽  
Composite Structures ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Epoxy Composites ◽  
Temperature Influence ◽  
Impact Properties ◽  
Different Temperatures ◽  
High And Low Temperatures ◽  
The Impact

The aim of this paper is to present the influence of high and low temperatures on the impact properties glass-epoxy composites. The impact strength an is presented for four different glass-epoxy composite structures at three different temperatures, i.e., at room temperature t=20?C, at an elevated temperature t=+50?C and at a low temperature t=-50?C. Standard mechanical testing was carried out on the composite materials with specific masses of reinforcement of 210 g m-2 and 550 g m-2 and orientations 0?/90? and ?45?. Micromechanical analysis of the failure was performed in order to determine real models and mechanisms of crack and temperature influence on the impact properties. .

scholarly journals Ageing and temperature effect on the fatigue performance of bituminous mixtures

2017 ◽  
Vol 7 (080) ◽  
pp. 126
Author(s):  
T. López-Montero ◽  
R. Miró
Keyword(s):  
Low Temperatures ◽  
Progressive Increase ◽  
Fatigue Performance ◽  
Relative Importance ◽  
Modified Bitumen ◽  
Asphalt Mixes ◽  
Bituminous Mixtures ◽  
Different Temperatures ◽  
Strain Sweep ◽  
Polymer Modified Bitumen

The ageing of asphalt mixes, together with their exposure to low temperatures, causes a progressive increase of cracking. In this paper, the effect of ageing and temperature on the fatigue of asphalt concretes made with two types of binders, conventional (50/70) and polymer modified bitumen (PMB), is studied. For this purpose, specimens previously subjected to an accelerated laboratory ageing process were tested by a strain sweep test at different temperatures (-5ºC, 5ºC and 20°C). Results were compared with the obtained from the unaged specimens showing the relative importance of ageing, temperature and type of bitumen on the parameters that determine the fatigue life of the mixture. The mixtures behaviour becomes more brittle with ageing and the decrease of temperature. However, ageing hardly has an effect on fatigue at lower temperatures. In general, mixtures made with polymer modified bitumen have a better fatigue performance to ageing and temperature.

Study on Basic Mechanical Behaviors of Rocks at Low Temperatures

2006 ◽  
Vol 306-308 ◽  
pp. 1479-1484 ◽  
Author(s):  
Quan Sheng Liu ◽  
Guang Miao Xu ◽  
Yun Hua Hu ◽  
Xiaoxiao Chang
Keyword(s):  
Young’S Modulus ◽  
Low Temperatures ◽  
Friction Angle ◽  
Test Results ◽  
Mechanical Behaviors ◽  
Rock Engineering ◽  
Cold Regions ◽  
Red Sandstone ◽  
Different Temperatures ◽  
Compressive Tests

Basic mechanical behaviors of rocks at different temperatures and with different moistures are required to be investigated for studying and designing rock engineering in cold regions. In this paper, two typical rocks, i.e., red sandstone and shale sampled from Jiangxi and Hubei in China, respectively, are tested by uniaxial and triaxial compressive tests at different temperatures ranging from 20°C to -20°C and in dry and fully saturated states. The test results show the different behaviors of them. The values of the uniaxial and triaxial compressive strengths, Young’s modulus, cohesion, and friction angle, increase with the lowering of the testing temperatures, but the tendencies are different for these two kinds of rock.

Simple Systems

2017 ◽  
Author(s):  
Jochen Rau
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
General Framework ◽  
Gibbs State ◽  
Macroscopic System ◽  
Basic Model ◽  
System A ◽  
Paramagnetic Salt ◽  
High And Low Temperatures ◽  
Simple Systems

Even though the general framework of statistical mechanics is ultimately targeted at the description of macroscopic systems, it is illustrative to apply it first to some simple systems: a harmonic oscillator, a rotor, and a spin in a magnetic field. These applications serve to illustrate how a key function associated with the Gibbs state, the so-called partition function, is calculated in practice, how the entropy function is obtained via a Legendre transformation, and how such systems behave in the limits of high and low temperatures. After discussing these simple systems, this chapter considers a first example where multiple constituents are assembled into a macroscopic system: a basic model of a paramagnetic salt. It also investigates the size of energy fluctuations and how—in the case of the paramagnet—these fluctuations scale with the number of constituents.

scholarly journals A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Florentina Golgovici ◽  
Mariana Prodana ◽  
Florentina Gina Ionascu ◽  
Ioana Demetrescu
Keyword(s):  
Low Temperatures ◽  
Artificial Saliva ◽  
Electrochemical Stability ◽  
Morphological Investigation ◽  
Dental Alloys ◽  
Ion Release ◽  
Icp Ms ◽  
Different Temperatures ◽  
Good Concordance ◽  
Increasing Temperature

The purpose of our study is to compare the behavior of two reprocessed dental alloys (NiCr and CoCr) at different temperatures considering the idea that food and drinks in the oral cavity create various compositions at different pH levels; the novelty is the investigation of temperature effect on corrosion parameters and ion release of dental alloys. Electrochemical stability was studied together with morphology, elemental composition and ions release determination. The results obtained are in good concordance: electrochemistry studies reveal that the corrosion rate is increasing by increasing the temperature. From SEM coupled with EDS, the oxide film formed on the surface of the alloys is stable at low temperatures and a trend to break after 310K. ICP-MS results evidence that in accordance with increasing temperature, the quantities of ions released from the alloys immersed in artificial saliva also increase, though they still remain small, less than 20 ppm.

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