Physical Rheological Properties Research Articles

Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt

REOB (Recycled Engine Oil Bottom) rejuvenated asphalt can solve the problems of environmental pollution and resource waste. In order to improve the performance of REOB rejuvenated asphalt, an SBS modifier was applied. An orthogonal test was carried out to optimize the preparation scheme of SBS/REOB-modified rejuvenated asphalt, and the physical rheological properties and microscopic mechanisms of modified rejuvenated asphalt with different SBS and REOB dosages were studied. The test results show that the optimal mixture of the SBS/REOB-modified and rejuvenated asphalt is 9% REOB + 4.5% SBS, the optimal shear time is 40 min, and the shear rate is 5000 r/min. SBS modification of the REOB rejuvenated asphalt can obtain the same excellent high temperature performance as ordinary SBS-modified asphalt, and the modification process can greatly improve the high-temperature deformation resistance of rejuvenated asphalt. After SBS modification of the REOB rejuvenated asphalt, its S value is significantly lower than the base asphalt and the REOB rejuvenated asphalt, and its m value is also greatly improved compared with the base asphalt and the REOB rejuvenated asphalt, indicating that the low-temperature performance of the modified rejuvenated asphalt is greatly improved compared with the rejuvenated asphalt and is better than the base asphalt. The fluorescence microscopic test revealed that both the modified rejuvenated asphalt and the SBS-modified new asphalt prepared in the laboratory showed a continuous asphalt phase, and the SBS phase of the modified rejuvenated asphalt could basically reach the level of finished modified asphalt.

Mechanical Behavior of Low-Density Polyethylene Waste Modified Hot Mix Asphalt

The use of polymeric waste in the modification of asphalt binders for the construction of road pavements is a technique studied several years ago. However, the use of these materials involves high temperatures close to 190 °C, which generate large environmental impacts due to their emissions. In this study, an asphalt cement (AC) with low-density polyethylene (LDPE) residue contents of 5%, 7%, and 10% with respect to the mass of the AC was modified by the wet method. The modification was carried out using a temperature of 150 °C with the aim of preventing the oxidation of the AC and reducing the emissions generated at high temperatures. Based on the physical-rheological properties of the modified asphalt binder, it was found that 5% LDPE produces the best performance. Subsequently, a hot-mix asphalt type HMA-19 control without a modified asphalt binder and another with a modified asphalt binder were manufactured in order to evaluate the mechanical behavior by means of the Marshall test, an indirect tensile strength (ITS) test, resilient modulus (RM) testing, resistance to fatigue testing, permanent deformation testing, and the Cantabro test. Additionally, the asphalt mixtures were tested under the conditions of short-term aging (STOA, Short-Term Oven Aging), long-term aging (STOA + LTOA, Long-Term Oven Aging), and partial saturation with water (STOA + LTOA + water). Based on the results, an ANOVA analysis of variance was performed to assess whether the changes in the mechanical response of the modified mixture are statistically significant with respect to the control mixture. As a general conclusion, it is reported that mixtures with LDPE can be used for thick layers in high-temperature climates in order to control rutting.

Intrauterine Injection of Umbilical Cord Mesenchymal Stem Cell Exosome Gel Significantly Improves the Pregnancy Rate in Thin Endometrium Rats

Human umbilical cord mesenchymal stem cell (HUMSC)-exosome gel played a significant role in promoting thin endometrial receptivity and improving the pregnancy rate by inhibiting endometrial fibrosis and accelerating subendometrial microangiogenesis. High-quality HUMSC-exosome were obtained by pretreating HUMSC with transforming growth factor-β1 (TGF-β1). Exosome gel mixture has good biocompatibility and physical rheological properties, stabilizing the structure of exosomes and prolonging the action of exosomes in the uterine cavity. HUMSC or HUMSC-derived exosomes were used to treat rat model of thin endometrium. In animal experiments, four groups, including the HUMSC, HUMSC-exosome, model (negative control), and sham operation groups, were designed. The therapeutic effects were evaluated by the thickness of the endometrium, the number of glands, the subendometrial vessel density, the markers of endometrial receptivity, and the pregnancy rate. In an in vivo study, three groups, involving HUMSC-coculture, HUMSC-exosome, and the control, were explored. The proliferation and migration of the human endometrial stromal cells (HESCs) were further determined by cell scratch and 5-ethynyl-2′-deoxyuridine (EdU) assays. The protein expression of the TGF-β1/smad2/3 signaling pathway was determined by Western blot. After treatment, the thickness of the endometrium, the number of glands, and the subendometrial microangiogenesis were obviously increased, and the level of inhibition of endometrial fibrosis, molecular markers of endometrial receptivity, and the pregnancy rate were also significantly improved. HUMSC-exosome and HUMSC significantly promoted the migration and proliferation of HESCs. And it was confirmed that HUMSC-exosome were superior to HUMSC in inhibiting HESCs fibrosis through TGF-β1/smad2/3 signaling pathway at the protein expression level.

Influence of characteristics of recycling agent on the early and long-term performance of regenerated SBS modified bitumen

The increasing reclaimed asphalt pavement mixture causes environmental pollution and a waste of resource, which could be resolved by the asphalt recycling technology. In this paper, corn oil, waste engine oil, vacuum stream oil and cashew shell oil are used for rejuvenating aged SBS modified asphalt (ASMA), and the effect of composition, structure and thermal-oxidative stability of recycling agents on the early and long-term performance of rejuvenated binder are thoroughly investigated. The results indicate cashew shell oil with nut phenol derivatives has the best rejuvenating effect on ASMA, corn oil containing aliphatic hydrocarbons is more conducive to improving the low temperature performance of rejuvenated ASMA, and vacuum stream oil containing nonpolar alkane compound shows the worst regeneration effect. Meanwhile, simultaneous thermal analysis reveals nonpolar aliphatic hydrocarbons vacuum stream oil has the poorest thermal stability for its lowest initial decomposition temperature 146 °C, while initial decomposition temperature of cashew shell oil and corn oil are all over 200 °C. The changes of physical and rheological properties of cashew shell oil rejuvenated ASMA after aging are much smaller than that of others, which indicates cashew shell oil with excellent thermal-oxidative stability is more conductive to inhibiting the transition from viscosity to elasticity of rejuvenated binder in the aging process. While vacuum stream oil rejuvenated ASMA shows the most serious aging degree, suggesting the poor thermal-oxidative stability of recycling agents has adverse effects on the anti-aging properties of rejuvenated binder. Infrared spectrum analysis indicates the aging index growth rate of cashew shell oil rejuvenated ASMA is the smallest, also demonstrating the best aging resistance of cashew shell oil rejuvenated ASMA. The correlation coefficients between sulfoxide index and physical-rheological properties are almost all higher than 0.90, while that between sulfoxide index and physical-rheological properties are lower than 0.71, therefore sulfoxide index can be a better indicator for estimating the physical-rheological properties of rejuvenated SBS modified bitumen in the service.

Microbit Dynamic Filtration Studies

Published in Petroleum Transactions, AIME, Volume 210, 1957, pages 183–189. Abstract A laboratory study of the effects of physical and easily measured rheological properties upon dynamic filtration was carried out. The purpose was to determine the factors affecting dynamic filtration and thus learn how to control this important property. The recommended procedure for determining the amount of fluid loss prescribed by API Code RP 29 "Field Procedure for Testing Drilling Fluids," is very useful for mud conditioning purposes, but inadequate for comparing filtration properties of different muds under dynamic conditions. Where dynamic filtration control becomes important for purposes such as logging and coring, other means of evaluating filtration properties are needed. A special device and testing technique were developed to provide reliable data on filtration characteristics of different fluids under dynamic conditions. Liquid saturated rock samples were drilled with a microbit, and the amount of connate liquid displaced by the fluid being investigated was measured. The empirical testing procedure was considered reliable. A large number of laboratory-prepared and field-mixed drilling fluids with a wide range of physical properties were studied. These properties included:shape of consistency curves,apparent viscosity,plastic viscosity,yield value,density, andAPI filter loss. Test results indicate that very little, if any, trend could be established between changes in these fluid properties and dynamic filtration. Introduction During the process of drilling, excessive loss of liquid from the mud to the formation is undesirable for many reasons. Filtration can reduce production-zone permeability, cause sloughing of formations, affect electric log curves, and render the fluid data obtained from cores unreliable. Thus, it is very important that we gain a knowledge of the factors that control filtration. It is generally agreed that in any type of filtration (static, dynamic, or combinations thereof), the mechanics of filtering depend in great part upon the composition of the fluid. Moreover, it is also true that the physical and rheological properties are influenced by the composition of the fluid. Indirectly, then, it was hypothesized that a relationship existed between dynamic filtration and physical-rheological properties, two effects of a common cause - fluid composition.