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1

Investigation the effect of newly used polymer modified bitumen on the performance of hot mix asphalt containing reclaimed asphalt pavement

Chafat Osamah H., Al-Ghurab Sahar B., Al-Humeidawi Basim H.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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Vol. 30, No. 3

451--463

EN

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value.

2

Viscosity and creep compliance of polyoxymethylene copolymers of various average molecular weights

Gonzalez-Gutierrez J., Oblak P., Megen Z. M., Emri I.

Polimery

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2015

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T. 60, nr 10

620--627

EN

The effect of average molecular weight (Mw ) of polyoxymethylene (POM) on melt viscosity and solid state creep compliance were investigated. Viscosity follows the power function of Mw. Creep compliance results indicate that time-temperature superposition applies to POM copolymers. Creep compliance in ashort time (0.25 s) is independent of Mw, but in a longer time (10 years) it follows an inverse power law relation with Mw, up to a critical value of Mw = 81 100, where creep compliance becomes independent of Mw. At intermediate time (17 min), similar to short one, no effect on susceptibility to creep compliance was observed. It was also stated that the activation energy is independent of Mw.

PL

Zbadano wpływ średniego ciężaru cząsteczkowego (Mw) wybranych kopolimerów polioksymetylenowych (POM) na lepkość stopu i podatność na pełzanie próbki w stanie stałym. Stwierdzono, że w przypadku wszystkich badanych kopolimerów POM zależność lepkości od Mw opisuje funkcja potęgowa. Wyniki badań podatności na pełzanie wykazały zgodność z zasadą równoważności temperaturowo-czasowej. Podatność na pełzanie w krótkim czasie (0,25 s) była niezależna od Mw, natomiast w czasie dłuższym (10 lat) wielkość ta zmniejszała się ze zwiększaniem Mw, aż do wartości krytycznej Mc = 81 100, po której nie zależała już od Mw. W średnim czasie (17 min), podobnie jak w czasie krótkim, Mw nie wpływał na podatność na pełzanie. Zaobserwowano również, że energia aktywacji nie jest funkcją Mw.

3

Young's modulus and creep compliance of GaAs and Ga1-xMnxAs ferromagnetic thin films under thermal stress at varied manganese doping levels

Kemei S. K., Kirui M. S. K., Ndiritu F. G., Ngumbu R. G., Odhiambo P. M., Leite D. M. G., Pereira A. L. J., Da-Silva J. H. D.

Materials Science Poland

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2015

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Vol. 33, No. 2

340--347

EN

Dynamical mechanical analysis yields information about the mechanical properties of a material as a function of deforming factors, such as temperature, oscillating stress and strain amplitudes. GaAs and Mn-doped GaAs at varied levels, used in making electronic devices, suffer from damage due to changes in environmental temperatures. This is a defective factor experienced during winter and summer seasons. Hence, there was a need to establish the best amount of manganese to be doped in GaAs so as to obtain a mechanically stable spin injector material to make electronic devices. Mechanical properties of Ga1-xMnxAs spin injector were studied in relation to temperatures above room temperature (25 degrees C). Here, creep compliance, Young's moduli and creep recovery for all studied samples with different manganese doping levels (MDLs) were determined using DMA 2980 Instrument from TA instruments Inc. The study was conducted using displace-recover programme on DMA creep mode with a single cantilever clamp. The samples were prepared using RF sputtering techniques. From the creep compliance study it was found that MDL of 10 % was appropriate at 30 degrees C and 40 degrees C. The data obtained can be useful to the spintronic and electronic device engineers in designing the appropriate devices to use at 30 degrees C and above or equal to 40 degrees C.

4

On the convergence of workings and the purpose of working observations in salt mines

Kortas G.

Geology, Geophysics and Environment

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2012

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Vol. 38, no. 1

51-68

EN

In this paper, the author has presented the definitions of convergence as a stream of displacement vector field. The author has presented equations of the convergence of workings (chambers, caverns), in the shape of geometric primitives, as well as identified and described the stages of convergence development in time. Basic principles of convergence are discussed, associating main convergences in a rectangular cavern with its dimensions and volumetric convergence. The current status of knowledge has been used for the formulation of the objectives of conducting convergence measurements in underground salt mines. The description of the convergence stages and the study of a rectangular chamber are educational in nature, while the identified objectives of observations can be applied for designing convergence observations and interpretation of results.

PL

W pracy przedstawiono definicje konwergencji jako strumienia pola wektorowego przemieszczenia. Określono wzory na konwergencję wyrobisk w kształcie prymitywów geometrycznych oraz wyodrębniono i scharakteryzowano fazy rozwoju konwergencji w czasie. Omówiono podstawowe zasady zaciskania wyrobisk, wiążące główne konwergencje w komorze prostopadłościennej z jej wymiarami i konwergencją objętościową. Dotychczasowy stan wiedzy wykorzystano do sformułowania celów prowadzenia pomiarów konwergencji w podziemnych kopalniach soli. Opis faz konwergencji i studium konwergencji w prostopadłościennej komorze mają walory poznawcze, a wyłonione cele obserwacji mogą być wykorzystane przy projektowaniu obserwacji konwergencji i interpretacji ich wyników.

5

Prediction of asphalt creep compliance using artificial neural networks

Zofka A., Yut I.

Archives of Civil Engineering

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2012

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Vol. 58, nr 2

153-173

EN

Creep compliance of the hot-mix asphalt (HMA) is a primary input of the current pavement thermal cracking prediction model used in the US. This paper discusses a process of training an Artificial Neural Network (ANN) to correlate the creep compliance values obtained from the Indirect Tension (IDT) with similar values obtained on small HMA beams from the Bending Beam Rheometer (BBR). In addition, ANNs are also trained to predict HMA creep compliance from the creep compliance of asphalt binder and vice versa using the BBR setup. All trained ANNs exhibited a very high correlation of 97 to 99 percent between predicted and measured values. The binder creep compliance functions built on the ANN-predicted discrete values also exhibited a good correlation when compared with the laboratory experiments. However, the simulation of trained ANNs on the independent dataset produced a significant deviation from the measured values which was most likely caused by the differences in material composition, such as aggregate type and gradation, presence of recycled additives, and binder type.

6

Viscoelastic model of waterhammer in single pipeline - problems and questions

Weinerowska-Bords K.

Archives of Hydro-Engineering and Environmental Mechanics

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2006

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Vol. 53, nr 4

331-351

EN

In the paper, viscoelastic model of waterhammer in a single polymer pipeline is analysed. The theoretical background of viscoelastic behaviour of the structure is shown and the mathematical model of waterhammer in a polymer pipeline is presented. The main problems connected with applying the model are discussed. The main emphasis is on the question of parameter estimation. Important aspects of wave speed calibration are presented. Estimation of a second group of parameters - retardation time and creep compliance values - was analysed. Problems and questions connected with the number of parameters, methods of estimation, potential non-uniqueness of the solution and accuracy of obtained calculations were discussed.

7

Identyfikacja zmiennego w czasie współczynnika Poissona lepkosprężystych materiałów biologicznych na podstawie testu pełzania

Stankiewicz A.

Inżynieria Rolnicza

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2005

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R. 9, nr 14

339--346

PL

W pracy, opierając się na całkowych równaniach konstytutywnych, wyprowadzono wzór określający zależność pomiędzy zmiennym w czasie współczynnikiem Poissona materiału liniowo lepkosprężystego a funkcjami pełzania w stanach jednoosiowego odkształcenia i jednoosiowego naprężenia. Opracowano algorytm identyfikacji zmiennego w czasie współczynnika Poissona na podstawie dyskretnych pomiarów jednoosiowych funkcji pełzania, uzyskanych eksperymentalnie dla próbki swobodnej i próbki ograniczonej w podwójnym teście pełzania.

EN

The need for knowledge of time-dependent viscoelastic material functions has been growing with the increased use of an accurate engineering methods for rigorous predictions of the plant materials behaviour, such as the finite element method (FEM) and the boundary element method (BEM). Essentially, only linear viscoelasticity is considered for which the correspondence principle applies. A new method for computing the time-dependent Poisson's ratio of linear viscoelastic materials, using discrete time-measurements of the uniaxial creep compliance of unconfined and a laterally constrained cylindrical specimens of the material obtained in double creep experiment, is developed on the basis of the constitutive convolution integral equations. The approach proposed solves the problem in Laplace transform domain and relies on numerical inversion for the determination for the time-dependent Poisson's ratio. The method combines effectiveness and accuracy and is general enough to cover both viscoelastic solids and liquids.

8

Algorytm identyfikacji zmiennego w czasie współczynnika Poissona lepkosprężystych materiałów roślinnych opisanych modelem Kelvina

Stankiewicz A.

Inżynieria Rolnicza

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2005

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R. 9, nr 14

331--338

PL

W pracy rozważa się problem wyznaczania zmiennego w czasie współczynnika Poissona roślinnych materiałów liniowo lepkosprężystych opisanych uogólnionym modelem Kelvina na podstawie pomiarów funkcji pełzania w stanach jednoosiowego odkształcenia i jednoosiowego naprężenia. Dla pięcioparametrowych modeli Kelvina pokazano, że współczynnik Poissona można przedstawić jako sumę składowej stałej, funkcji wykładniczych oraz splotów pierwotnych i zmodyfikowanych funkcji Bessela oraz podano dokładny analityczny algorytm obliczeniowy. Przedstawiono schemat identyfikacji zmiennego w czasie współczynnika Poissona na podstawie dyskretnych pomiarów jednoosiowych funkcji pełzania, uzyskanych w podwójnym teście pełzania. Efektywność metody zilustrowano wyznaczając zmienny w czasie współczynnik Poissona próbek korzenia buraka cukrowego.

EN

Most of the constitutive models of biological materials are for a viscoelastic regime, which is good for characterising strain-stress dependence, creep and stress relaxation within a small deformation. The stress and strain problems of biological materials are usually solved in the time domain, where the dynamic properties can effectively be characterised by the time-dependent Poisson's ratio. In this paper the problem of the Poisson's ratio determining using discrete time-measurements of the uniaxial creep compliance of unconfined and a laterally constrained cylindrical specimens of the material obtained in double creep experiment is considered. It is proved that for five-element Kelvin models of the uniaxial relaxation functions the Poisson's ratio can be described as a linear combination of constant and exponential functions and multiple convolution integrals of original and modified Bessel functions. A resulting identification scheme is outlined. The effectiveness of the method is demonstrated through the computation of the Poisson's ratio of the beet sugar root samples.