Rheological properties and microscopic mechanism of waste cooking oil activated waste crumb rubber modified asphalt

In this paper,the surface activated crumb rubber with waste cooking oil(WCO)was studied to improve the performance of crumb rubber modified asphalt.The activated waste crumb rubber modified asphalt(OCRMA)with different amount of crumb rubber was prepared to study the microscopic appearance of OCRMA by scanning electron microscope and fluorescence microscope and analyze the surface performance.The rheological properties and microscopic mechanism of OCRMA were characterized by dynamic shear rheological test,multiple stress creep recovery(MSCR)test,BBR test and infrared spectroscopy.The results show that the dissolution degree of waste crumb rubber is improved after WCO activation,and the compatibility with asphalt components is enhanced,and the stable cross-linking structure is formed,which improves the asphalt performance.The several new absorption peaks,which were obvious,were all caused by the composition of WCO,that is,there was no significant chemical change during the interaction between the activated crumb rubber and base asphalt.Compared with the common waste crumb rubber modified asphalt(CRMA),activation with WCO can significantly reduce the viscosity of CRMA,decrease the difference of segregation softening point by 27%,and enhance the low temperature performance by 30%.The aging degree is greatly reduced,and the anti-aging performance of OCRMA is increased by about 20%with the same dosage.The high temperature performance,though higher than that of base asphalt,decreases to some extent.After comprehensive analysis,the optimal dosage of crumb rubber for OCRMA is 30%.

Female Struggle in Patriarchal Society-Comparative Interpretation of Gimmal and Crumbs of Agalloch Eaglewood-the First Incense Burner

Zhang Ailin created so many various kinds of female charaters in her novels;females who own distinct characters and identities just have similar fates and struggles.This paper tries to probe into the similar fates and struggles of two heroines with different identities in the same social background by analysing the novel Gimmal and Crumbs of Agalloch Eaglewood-the First Incense Burner from perspective of feminism.

极性蛋白Crumbs胞内域功能保守性研究

跨膜蛋白Crumbs(Crb)是细胞顶部的决定因子,对上皮细胞顶?底极性的建立和维持起着关键的作用。其胞内域虽然仅有37个氨基酸,但对Crb的功能必不可少。在果蝇(Drosophila melanogaster)中,如果胞内域发生突变,将造成胚胎发育异常、上皮细胞顶底极性丧失等严重后果。Crb胞内域从果蝇到小鼠(Mus musculus)和人类(Homo sapiens)具有很高的同源性,但线虫(Caenorhabditis elegans)两个Crb蛋白的胞内域与果蝇和哺乳动物却较为不同。为验证线虫Crb蛋白胞内域是否功能保守,本文利用基因组工程法(Genomic engineering),将果蝇基因组中Crb基因编码胞内域的部分替换为一致性和相似性较远的线虫Crb2基因的相应区段。与其他Crb胞内域突变果蝇不同,替换突变体胚胎发育正常,Crb及其他极性蛋白的表达和定位正常,胚胎上皮细胞顶底极性能够正确的建立和维持。这些结果证实虽然线虫和果蝇Crb蛋白胞内域之间存在大量序列变异,但重要的氨基酸位点和功能模块则完全保守。

Modification of Bitumen with Desulfurized Crumb Rubber in the Present of Reactive Additives

Bitumen was modified with desulfurized crumb rubber (DCR) in the present of reac tive additives. The effect of the kinds and content of the reactive additive on prop erties of DCR modified bitumen (DCRMB) was investigated. The morphology of DCRMB was characterized by SEM and the changes of the chemical structure of DCRMB wit hout and with the addition of the reactive additive were analyzed by FTIR. The e xperimented results show that the softening point,the elasticity recovery and th e storage stability of DCRMB were improved significantly by the addition of the reactive additive. This is because that a network structure of rubber in DCRMB w as formed and the chemical reaction between C=C double bonds in bitumen and DCR has happened after the reactive additive was added into DCRMB.

Experimental evaluation of mechanically stabilized earth walls with recycled crumb rubbers

Traditional techniques for treatment of waste rubber, such as burning, generate some highly non- degradable synthetic materials that cause unrepairable environmental damages by releasing heavy metals, such as arsenic, chromium, lead, manganese and nickel. For this, scrap tires are used as light- weight alternative materials in many engineering applications, such as retaining wall backfilling. In the present study, 90 laboratory models were prepared to evaluate the stability of mechanically stabilized earth （MSE） walls with plate anchors. Then, the bearing capacity and horizontal displacements of the retaining walls were monitored by exerting a static loading to investigate the effects of adding different contents （5 wt%, 10 wt%, 15 wt% and 20 wt%） of recycled crumb rubber （RCR） to the fill of a mechanically stabilized retaining wall with plate anchors. To visualize the critical slip surface of the wall, the particle image velocimetry （PIV） technique was employed. Results showed that the circular anchor plates almost continually provided a higher bearing capacity and wall stability than the square plates. Moreover, the backfill with 15 wt% RCR provided the maximum bearing capacity of the wall. Increasing the weight percentage of RCR to 20 wt% resulted in a significant reduction in horizontal displacement of the wall, which occurred due to the decrease in lateral earth pressure against the whole walls. An increase in RCR content resulted in the decrease in the formation of failure wedge and the expansion of the wall slip surface, and the failure wedge did not form in the sand mixtures with 15 wt% and 20 wt% RCRs.

Microscopic and Dynamic Rheological Characteristics of Crumb Rubber Modified Asphalt

A test for crumb rubber modified asphalt containing 20% crumb rubber particles（30 mesh） was performed using a scanning electron microscope（SEM）.The experimental results indicate that the crumb rubber particles are evenly distributed in the asphalt.Shear rate sweep and shear-temperature sweep tests on the crumb rubber modified asphalt at-20-80 ℃ using a dynamic shear rheology（DSR） instrument,were carried out.The tests show that the complex modulus decreases with increasing temperature;at equivalent temperature,higher load frequencies lead to a larger complex modulus,and this value increasingly decreases as the temperature increases;the phase angle increases with temperature and decreases as the load frequency increases.It can be concluded that the rutting resistance limiting temperature of crumb rubber modified asphalt is 78 ℃,and the anti-fatigue limiting temperature is 16 ℃,which shows that the asphalt has preferable rutting resistance characteristics at high temperature,as well as anti-fatigue characteristics.In addition,the complex modulus master curve at different temperatures was plotted according to the time temperature equivalence principle,which allows the study of the dynamic state behavior of crumb rubber modified asphalt at a wide range of load frequency.

Microstructure and Properties of Desulfurized Crumb Rubber Modified Bitumen

The microstructures of general crumb rubber(CR), dynamic desulfurized crumb rubber(DDCR) and high speed agitation desulfurized crumb rubber(HSADCR) modified bitumens were investigated by a fluorescence microscope, and the physical properties of these three modified bitumens were studied.The results show that the dynamic desulfuration can improve the swelling capacity of crumb rubber in bitumen by destroying the sulfuratized bond of the crumb rubber,but the reunion of rubber particles during dynamic desulfuration also makes the swelling and the DDCR in bitumen difficult, so properties of the DDCR modified bitumen are not superior to the general crumb rubber modified bitumen.However,high speed agitation desulfuration can not only improve the swelling capacity of crumb rubber in bitumen,but also avoid the reunion of rubber particles,so some properties of bitumen can be improved by the modification of HSADCR.

The Mechanism of Asphalt Modification by Crumb Rubber

To investigate the mechanism of asphalt modification by crumb rubber,the interactions between FCC slurry and rubber particles were evaluated at different temperatures and time.The rules of the change in mass of SARA composition in FCC slurry were obtained before and after its interaction with rubber particles,which showed that crumb rubber not only absorbed saturates and aromatics but also resins.Asphaltenes promoted the desulfurization or degradation of crumb rubber during the interaction between asphalt and crumb rubber.

Laboratory and Field Investigations of Polymer and Crumb Rubber Modified Bitumen

In this paper, properties of new kind of modified bitumen are presented. Bituminous binder was modified with mix modification using polymer and additive of crumb rubber. Terminal blend process at the refinery was applied to produce the mixed modified binder. Laboratory tests were focused on the characterization of the properties of 45/80-55 CR binder with comparison to reference 50/70 and conventional polymer modified 45/80-55 bitumen. Based on conventional binder tests such as penetration, softening point and Fraass breaking point as well as BBR （bending beam rheometer） and DSR （dynamic shear rheometer） tests, rheological properties were investigated. For determination of stability of the polymer and crumb rubber, modified bitumen tube testing method was used. Based on the results analysis, improvement of the viscoelastic properties of polymer and crumb rubber modified bitumen was observed. Conventional properties and stability tests showed that it is possible to pass standard requirements for polymer modified bitumen. Mixed modification and terminal blend allow to use crumb rubber as a modifier with elimination of the separation of crumb rubber during transportation and storage at high temperature. In this paper, experience from filed sections with use of the asphalt mixture with new kind of modified bitumen is presented.

Laboratory investigation on effects of organic montmorillonite on performance of crumb rubber modified asphalt

In this paper,organic montmorillonite(OMMT)was added into crumb rubber modified asphalt(CRMA)to improve its high temperature performance,anti-aging performance and storage stability.The effects of different OMMT content on properties of CRMA were studied.The rutting factor obtained by dynamic shear rheological(DSR)test was adopted to evaluate the high-temperature performance.The creep stiffness and m value determined by the bending beam rheometer(BBR)test were employed to evaluate the low-temperature performance.The softening point,ductility,rutting factor before and after rolling thin film ovens test(RTFOT)and pressure aging vessel test(PAV)were compared to characterize the aging properties.Moreover,the segregation test after being reserved for 48 h and 7 d was conducted,and the softening point and rutting factor of upper and lower layers of segregation pipe were adopted to evaluate the storage stability.The results indicated that the high-temperature performance and anti-aging performance were developed with the increasing content of OMMT,while the low-temperature performance deteriorated.The storage stability was improved with the increasing content of OMMT before the content exceeded 4%,after which the storage stability declined.Taking account of all factors,it is suggested that the optimum content of OMMT is 3%−4%.

Physical and Mechanical Properties of Crumb Rubber Mortar(CRM)with Interfacial Modifiers

Eight interfacial modifiers were used to improve the interfacial bonding strength between the crumb rubber and matrix of Crumb Rubber Mortar （CRM）, and the physical and mechanical properties and microstructure of CRM were also studied. The results show that, the interfacial modifiers obviously improve the interface bonding strength between the crumb rubber and matrix and the whole strength of CRM, and silicone modified styrene-acryl ate-emulsion has the best effect. The rubber-cement matrix interface was proved by SEM that the interfacial modifiers treated rubber showed good adhesion to the matrix.

Creep Characteristics of Crumb Rubber Modified Asphalt Binder

Crumb rubber modified asphalt containing 20 percent crumb rubber particles of 30 mesh has been examined by Scanning Electron Microscope （SEM） to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles in asphalt. The SEM pictures reveal that the crumb rubber particles distribute evenly in the asphalt and they are compatible well with asphalt. The shear creep test of crumb rubber modified asphalt was carried out at -10 ℃ and 40 ℃ by Dynamic Shear Rheology （DSR）. The shearing deformation at different temperature and creep stiffness modulus curve at loading stage of crumb rubber modified asphalt have been measured. The stiffness modulus of crumb rubber modified asphalt is much temperature sensitive and it decays much quick at the early stage of loading than normal asphalt. The rate of decay of stiffness modulus is slow at the subsequent stage and stiffness modulus approaches to a stable value at the final stage at a higher temperature. In addition, Burgers model is suitable to describe and simulate experimental results of viscoelastic properties of the crumb rubber modified asphalt.

Mechanism behind Time Dependent Elasticity of Crumb Rubber-Nano-Asphalt Hybrids Using Discrete Relaxation Spectrum

Crumb rubber powder is a successfully used renewable material obtained from waste tire rubber,which has been incorporated into paving asphalt since the 1930s due to its good resistance to deformation and fatigue as well as its eco-friendly performance.In this study,carbon nanotubes and nano silica were incorporated into the terminal blend crumb rubber modified asphalt technology to remedy the issues of excessive desulfurization and degradation of ground tyre rubber with this technology.The mechanism behind the high temperature delayed elastic properties of the crumb rubber-nano-asphalt hybrids was experimentally investigated based on discrete relaxation spectrum.Development of the discrete relaxation spectra was accomplished by fitting on the 60℃ storage modulus data tested by the dynamic shear rheometer using the generalized Maxwell model.Subsequently,the feasibility of characterizing delayed asphalt elasticity using main relaxation time was verified by test results from the 60℃ creep and recovery test.Results indicated that the crumb rubber-nano-asphalt hybrids exhibited arrheodictic behavior and the asphalt elasticity was strengthened by two nano agents.Moreover,the elasticity reinforcement with carbon nanotubes was greater than with nano silica.Additionally,a good correlation was observed between the 60℃ zero shear viscosity and main relaxation time,and greater 60℃ zero shear viscosity was correlated to longer main relaxation times.Furthermore,longer main relaxation time of the asphalt was related to greater average recovery rate in the creep and recovery test.This research is expected to shed some light on the mechanism behind time-dependent elasticity of crumb rubber modified asphalt from the perspective of polymer physics.

Crumbs homolog 2 mutation in two siblings with steroid-resistant nephrotic syndrome:Two case reports

BACKGROUND Crumbs homolog 2(CRB2)is a recently discovered gene that is closely related to the maintenance of normal polarity in podocytes;mutations can directly lead to steroid-resistant nephrotic syndrome(SRNS).However,the characteristics of nephrotic syndrome(NS)caused by CRB2 mutations have not been described.CASE SUMMARY We report a novel compound heterozygous mutation of the CRB2 gene in two siblings with SRNS.The two siblings had edema,proteinuria,hypoproteinemia and hyperlipidemia.Both their father and mother had normal phenotypes(no history of NS).Whole exon sequencing(WES)of the family showed a novel compound heterozygous mutation,c.2290(exon 8)C>T and c.3613(exon 12)G>A.Glucocorticoid therapy(methylprednisolone pulse therapy or oral prednisone)and immunosuppressive agents(tacrolimus)had no effect.During a 3-year follow-up after genetic diagnosis by WES,proteinuria persisted,but the patient was healthy.CONCLUSION CRB2 mutations related to SRNS often occur in exons 7,10,and 12.Clinical manifestations of SRNS caused by CRB2 mutations are often less severe than in other forms of SRNS.

Dynamic Behaviour of Pond Ash Mixed with Coir and Crumb Rubber

An experimental program was conducted to determine the dynamic properties of pond ash(PA)and pond ash mixed with admixtures like crumb rubber(CR)and coir fiber(CF)which are wastes of different industries.Additives CR and CF were mixed separately with pond ash in a percentage ranging from 0%–20%at an interval of 5%and 0%–2%at an interval of 0.5%by weight of pond ash,respectively.Dynamic properties(Shear modulus,Number of cycles to initiate liquefaction,Degradation index and Damping ratio)for pond ash mixes were determined using strain-controlled cyclic tri-axial apparatus.The shear strain was kept constant at 1.2%and the frequency varied from 0.4 to 1 Hz.Liquefaction resistance improves when crumb rubber is added to pond ash,however adding Coir fiber to pond ash has essentially no effect on the number of cycles required to initiate liquefaction.The dynamic shear modulus decreases when crumb rubber was mixed in pond ash whereas when coir fiber is added to pond ash,the dynamic shear modulus increases significantly.A mix of PA,CR,and CF was also tried to balance the number of cycles required to initiate liquefaction and shear modulus.The mixed sample in the proportion of PA(84%)+CR(15)+CF(1%)can be termed a balanced mix as the number of cycles to initiate liquefaction was more than all PA-CF mixes and also the shear modulus was more than all PA-CR mixes.Damping ratio increases with increasing frequency of loading(0.4 to 1 Hz).

Study on Low-Temperature Properties of the Asphalt Modified by Carbon Nanotubes(CNTs)and Crumb Rubber(CR)

The effect of adding crumb rubber(CR)and carbon nanotubes(CNTs)on the low-temperature properties of virgin asphalt was studied.Using the force-ductility test and the bending beam rheometer(BBR)test,the deformation resistance and rheological properties of asphalt samples at low temperatures were evaluated,respectively.Based on the result of BBR test,the creep functions of the Burgers model and the Zener model were used to fit the low-temperature creep characteristics of the asphalt samples.Furthermore,the differential scanning calorimetry(DSC)test and the attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR)test were utilized to appraise the low-temperature stability and chemical properties of asphalt samples,respectively.The results showed that CR significantly improved the low-temperature properties of virgin asphalt,while CNTs had little effect.Moreover,during the degradation of CR,aromatic and aliphatic components were released.In particular,the aliphatic components of CR-modified asphalt were much higher than those of virgin asphalt,which had a significant effect on improving the low-temperature properties of the asphalt.The DSC test results showed that CR enhanced the low-temperature stability of the asphalt,while the addition of CNTs presented a slightly negative effect.

In Tempore Belli： Reflections on the Sense of the Universal in George Crumb＇s Music of the Vietnam War

This paper proposes new ways to understand the sense of universality in music through a reflection and analysis of George Crumb＇s Black Angels （Images 1）： Thirteen lmages from the Dark Land, one of the defining musical expressions of the Vietnam War era. It centers on an analysis of the relationship of the body/self to an ＂ecology of war＂ produced through Crumb＇s music that renders these selves indistinct within this musical geography. The selves that inhabit Black Angels could be that of anybody in particular since Crumb seeks to invoke in his music the primeval experience of terror that inhabits in all of us as the inheritors of mankind＇s violence. This sense of the universal militates against the desirable qualities of popular music that rely on the production of autonomous and singular selves that make the distinction between enemy and friend possible and distinct. We focus on Crumb＇s use of archaisms, his construction of time in this piece, and the author＇s overall purpose to invoke a time of war rather than to reflect the conditions of war, in order to delineate the contours of the universal time and space producing the undifferentiated primeval self of war. We conclude that although Crumb＇s rejection of the national self deprives the piece of a salient place in the popular cannon of the war, it has left an intellectual legacy on the times of the Vietnam War that deserves to be preserved.

Crumb Rubber Modified Bitumen in Open Graded Wearing Course of Flexible Pavement

Rapid road infrastructure development due to an increasing demand of car users resulted in an increase in paved areas including road sites and suppression of green spaces. An integrated solution that can support a country’s economic development without compromising water pollution is becoming inevitable. Recycling tyres in the form of crumb rubber tyres and mixing it into bituminous paving mixture can increase the recycling rate and minimize cost of incineration process. In dry mixing process, five (5) different variations of Open Graded Wearing (OGW) course road samples were made to make up 1.15 kg in each sample. Each OGW mix contained 4% - 6% bitumen Pen 60/ 70 and fixed 1% of crumb rubber tyres, making the percentage of crumb rubber tyres 14% - 20% of bituminous samples. Bitumen Pen 60/70 mixed with 20% crumb rubber tyres content met the PG 76 bitumen properties. Physical properties of OGW made from crumb rubber modified bitumen (CRMB) were better than standard bitumen only. In a separate water leachate test using ICP-OES equipment, heavy metal leachate of Cu(II), Pb(II), Zn(II) and Cd(II) were present in all OGW CRMB samples at increasing surrounding water temperature from 25℃ to 60℃. However all the heavy metal concentration was very low below the allowable limit of trade effluent standards into water course.

Improved Resistance to Cracking of a Cement Mortar through the Incorporation of Crumb Rubber

Within a context of sustainable development, innovative processes for various applications to recycle rubber are put in place to make aggregates or crumb rubber. These uses include sports floor coverings, to manufacture of sealants, sound absorbing walls, to make roads, as an alternative fuel in cement kilns, etc. In this study, the addition of crumb rubber to mortar was investigated through optical and mechanical tests. The results showed that the incorporation of crumb rubber from used tires into mortar produced a better resistance to shrinkage cracking, but a compressive strength/tensile is reduced. This feature could lend itself to making playgrounds and sports grounds more absorbing and flexible, which would allow a more significant fall to be withstood without injury and consequently enhance the safety of playgrounds.

Using Crumb Rubber to Improve the Properties of Concrete from the Sustainability Point of View

In the past decade,the economy of China has been increasing at a remarkable speed,which causes the rapid increase of automobile industry.Researches in past years demonstrated that the incorporation of crumb rubber into concrete reduces the mechanical strength of concrete.However,properties such as plastic shrinkage cracking resistance,dry shrinkage cracking resistance,frost resistance,impact resistance,fatigue resistance etc.are improved due to the deformable feature of crumb rubber.Therefore,it is expected that using crumb rubber in concrete not only improves the properties of the material,but also reduces the environmental pressure of handling waste tires.