Low Temperature Rheological Properties Research Articles

Research on deepwater synthetic drilling fluid and its low temperature rheological properties

With the rapid development of deepwater drilling operations, more and more complex technical challenges have to be faced due to the rigorous conditions encountered. One of these challenges is that the drilling fluid used must had good rheological properties at low temperatures and high ability to inhibit hydrate formation. Synthetic drilling fluid has been widely applied to deepwater drilling operations due to its high penetration rate, excellent rheological properties, good ability to prevent hydrate formation, and high biodegradability. A synthetic drilling fluid formulation was developed in our laboratory. The rheological properties of this drilling fluid at low temperatures (0–20 °C) were tested with a 6-speed viscometer and its ability to inhibit hydrate formation was evaluated at 20 MPa CH4 gas and 0 °C by differential scanning calorimetry (DSC). Several factors influencing the low temperature rheological properties of this synthetic drilling fluid were studied in this paper. These included the viscosity of the base fluid, the amount of CEMU and organic clay, and the water volume fraction.

Laboratory evaluation on high temperature viscosity and low temperature stiffness of asphalt binder with high percent scrap tire rubber

The objective of this research is to utilize crumb rubber from scrap tires as an environmental friendly and sustainable additive for enhancing the high temperature and low temperature rheological properties of asphalt binders for asphalt pavements. Two different crumb rubber sources with different gradations – fine and coarse – were used in this project. The crumb rubber-modified (CRM) binder was produced by adding 10, 15, 20 and 25% crumb rubber particles by weight of a Superpave PG 64-22 asphalt binder. The CRM binders with and without Rolling Thin Film Oven (RTFO) aging were characterized by the AASHTO rotational viscosity test at 135, 140, 150, 160, 170, 177, and 190 °C (AASHTO T316). Furthermore, the low temperature cracking resistance of the binders was evaluated using the AASHTO Bending Beam Rheometer (BBR) test procedure at −12 and −18 °C (AASHTO T313). The statistical analysis of variance (ANOVA) was applied to quantify the effect of the influencing factors such as temperature, rubber particle size, and rubber concentration on the CRM binders’ performance. From the laboratory tests and ANOVA results in this study, it is evident that the addition of crumb rubber into asphalt binder can both significantly improve the viscosity of binder at high temperature and lower the creep stiffness at low temperature, which is beneficial to better both high temperature stability and low temperature cracking resistance of asphalt pavements. After RTFO aging, the viscosity decreases with increasing rubber concentration. Finer crumb rubber attains higher viscosity at high temperature and lower creep stiffness at low temperature. Considering the viscosity–temperature relationship, RTFO aging effects, creep stiffness decreasing percentage, and economical factors, 15% to 20% rubber asphalt ratio is proposed for the production of CRM binder.

Investigation of Low Temperature Properties for Ultraviolet Radiation Aged Bitumen and Mixture

Asphalt is an organic mixture with complex compounds and chemical structures which will change after exposed to heat, oxygen, and ultraviolet radiation (UV) and make the physical properties worse, especially at low temperature. In this paper, different aging levels (TFOT，UV-6days) of asphalt binders and mixtures with various mass ratio of layer clay powder to asphalt (0,3%,5%) were considered to investigate the low temperature rheological properties of aged asphalt binders and low temperature strength as well as fatigue properties. Dynamic Shear Rheomoter (DSR) and Universal Testing Machine (UTM) were used to evaluate low temperature properties of bitumen and mixture. From the results, after the addition of layer clay powder, the anti-aging properties is greatly improved and low temperature properties can be better maintained compared to base asphalt.

Estimation of rheological properties of RAP binder

The low-temperature rheological properties of binders in the recycled asphalt pavement (RAP) material without the damaging effects of solvent extractions were analyzed. The developed procedure is based on testing of bitumen-RAP mortars produced by mixing the fresh (virgin) binder with RAP material smaller than # 8 sieve. Different mortars were prepared, containing RAP material passing the #8 sieve and 15% by weight of fresh binder. Low temperature properties of these mortars were investigated by using the bending beam rheometer (BBR) test procedure that is specially modified for testing of the RAP mortars. The modification involved the development of a new kind of mold and different testing parameters. The RAP material used in the experimental study were both extracted from real reclaimed pavement and prepared in the laboratory, by aging binder through repeated PAV cycles. The results indicate the new procedure can capture the effect of aged properties of bitumen in the RAP and can be used to estimate the PG low temperature grade of the blended binder. Although data is limited in size, the modification of the BBR appears to be simple and provide repeatable data.

Preparation and rheological characterization of asphalt binders reinforced with layered silicate nanoparticles

Bentonite clay (BT) and organically modified bentonite (OBT) were used to reinforce and modify a bituminous paving asphalt binder. The modified asphalt binders were produced by melt processing under sonication and shearing stresses. The interlayer spacing of silicate layers in bentonite, organically modified bentonite and the modified asphalt binders were analyzed by wide angle X-ray diffraction (WAXD). The softening point, viscosity and ductility of the modified asphalts were tested as a function of clay content and clay type. The dynamic shear rheological tests showed that the modified asphalts have higher rutting resistance. Bending beam rheometer (BBR) test results for aged specimens (through rolling thin film oven (RTFO) and pressure aging vessel (PAV)) indicated that adding BT and OBT can significantly improve low temperature rheological properties and cracking of asphalt.

Rheological and fracture characteristics of low penetration grade bitumen

ABSTRACT Interest in the rheological and fracture characteristics of low penetration grade bitumens has increased in recent times due to greater use of progressively stiffer base materials and the growing concern over the durability of these extremely hard, high stiffness modulus materials. This paper investigates the high and low temperature rheological characteristics, tensile fracture modes and cohesive properties of a series of semi-blown, polymer modified and straight-run (direct distillation) low (15) penetration grade bitumens using a Brookfield (rotational) viscometer, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), Direct Tension Tester (DTT) and Vialit Pendulum Cohesion apparatus. The binders have been tested in their virgin (unaged) condition and after short-term, Rolling Thin Film Oven Test (RTFOT) and long-term, High Pressure Ageing Test (HiPAT) ageing. The results show considerable differences in the high and low temperature rheological and fracture properties of the 15 penetration grade bitumens as a function of their production method especially after ageing, although only minor differences in terms of their cohesive properties. In general the semi-blown 15 pen bitumen showed a higher susceptibility to ageing than the polymer modified and direct distillation 15 pen bitumens and an increased elastic “brittle” response to loading in terms of DSR, BBR and DTT test data.

Low Temperature Properties of Crumb Rubber Modified Binders

ABSTRACT This paper presents a study to evaluate low temperature rheological properties of crumb rubber modified binders and the impact of the rubber particle size and content on such properties. Three sizes of the crumb rubber (0.18 mm, 0.425 mm and 2.0 mm), a control (0 percent) and two levels of crumb rubber content (12 percent and 24 percent) were used with four asphalt binders. The measured rheological properties consisted of creep stiffness (St) and logarithmic creep rate (m). Results showed that: increasing the crumb rubber content decreased the creep stiffness which improves thermal cracking resistance. The impact of crumb rubber content on the m-value was very highly inconsistent. The crumb rubber size did not have a significant effect on the low temperature properties. Any effect of the size of the crumb rubber on the resistance to thermal cracking was dependent on the asphalt binder type. The analysis of the data generated in this experiment showed that some combinations of crumb rubber size and content can either improve or jeopardize the PG low temperature grade of the asphalt binder.

Low Temperature Properties of Crumb Rubber Modified Binders

ABSTRACT This paper presents a study to evaluate low temperature rheological properties of crumb rubber modified binders and the impact of the rubber particle size and content on such properties. Three sizes of the crumb rubber (0.18 mm, 0.425 mm and 2.0 mm), a control (0 percent) and two levels of crumb rubber content (12 percent and 24 percent) were used with four asphalt binders. The measured rheological properties consisted of creep stiffness (St) and logarithmic creep rate (m). Results showed that: increasing the crumb rubber content decreased the creep stiffness which improves thermal cracking resistance. The impact of crumb rubber content on the m-value was very highly inconsistent. The crumb rubber size did not have a significant effect on the low temperature properties. Any effect of the size of the crumb rubber on the resistance to thermal cracking was dependent on the asphalt binder type. The analysis of the data generated in this experiment showed that some combinations of crumb rubber size and content can either improve or jeopardize the PG low temperature grade of the asphalt binder.

Low Temperature Studies of Amorphous, Interfacial, and Crystalline Phases in Asphalts Using Solid-State 13C Nuclear Magnetic Resonance

The road performance behavior of an asphalt depends upon its susceptibility to changes in its rheological properties with time and temperature. One important fundamental molecular property of an asphalt, which dictates its temperature-dependent performance, is the nature of the molecular motions associated with the asphalt molecular components. Changes in the rotational motions of the methyl carbons and the segmental motions of the methylene carbons in the 1- to 10-kHz frequency range were studied (via changes in spin-spin dipolar-dephasing relaxation times) as a function of temperature for three Strategic Highway Research Program asphalts using carbon-13 dipolar-dephasing cross polarization with magic angle spinning nuclear magnetic resonance. The data indicate that the rotational motion of the terminal methyl carbons of n-alkanes in the amorphous phase is nearly independent of decreasing temperature until the glass-transition region is reached. Below the Tg, the rotational motion of the methyl carbons decreases slowly with decrease in temperature for asphalts AAA-1 and AAB-1. However, the methyl rotation in asphalt AAM-1 decreases more rapidly. The segmental motions of the methylene carbons in the mobile-amorphous phase for the different asphalts decrease rapidly with decreasing temperature from 20 to – 20°C. At temperatures below — 20°C, the segmental motions have essentially ceased. The slow, low-frequency motions of the methylene carbons in the inter-facial (rigid-amorphous) and crystalline phases were found to be independent of temperature above and below Tg. It is suggested that the methyl rotation and segmental motions of the methylene carbons in the amorphous phase extensively influence the low-temperature rheological properties of asphalts.