Effect Of Polyphosphoric Acid Research Articles

Effect of PolyPhosphoric Acid on Rutting Resistance of Asphalt Concrete Mixture

The action of high repeated trucks load associated with dramatically elevated ambient temperatures leads to the most harmful distress in asphalt pavements occurred in Iraq known as rutting. Essentially, it is produced from the accumulation of irrecoverable strains, which mainly occurred in the asphalt layers. That visually demonstrated as a longitudinal depression in the wheel paths as well as small upheavals to the sides. Poly Phosphoric Acid (PPA) has been used as a means of producing modified asphalt binders and the interest to use it has increased in recent years. The PPA provides modified asphalt binder, which is relatively cheaply produced compared to polymer-modified asphalt. In this paper, PPA was used by three-percentages 1, 2 and 3 % of the weight of asphalt binder. Two asphalt binder grades were used in this study, 40-50 and 60 -70. The evaluation process based on conducting Marshall Test, Compressive strength test and the Wheel Tracking test. The optimum asphalt content was determined for eight asphalt mixture. The results of the index of retained strength of modified asphalt were slightly increased compared with conventional mixtures. The rut depth was determined by using wheel tracking device at different temperature (45 and 55 ºC) for each asphalt mixture under 10000 cycles and the results showed that modified asphalt with PPA produced mixtures with more rutting resistance than conventional asphalt mixture. Moreover, the effect of PPA on rutting resistance for asphalt grade 60-70 was higher than asphalt grade 40-50.

Evaluation of UV aging behaviors of polyphosphoric acid (PPA) modified asphalt and its asphalt mixture

Effects of polyphosphoric acid (PPA) on the ultraviolet (UV) aging properties of asphalt and asphalt mixture were studied. The morphologies of these binders were characterized by FTIR spectra and TG analysis, then the influence of PPA on asphalt and its mixture before and after UV aging were investigated by the physical properties and pavement performances. Results show that the mechanisms of PPA modified asphalt are physical and chemical reactions; both UV aging and PPA additive could prompted the polycondensation of light components in asphalt. Compared with control samples, the introduction of PPA enhances the asphalt properties and intensifies the asphalt mixture performances. Furthermore, the asphalt performance aging variations (penetration aging index, softening point increment, ductility aging index, G*/sinδ aging index) decrease significantly due to the introduction of PPA. This manifests that the effects of UV aging on the behaviors of asphalt and asphalt mixture are restricted by the addition of PPA through inhibiting the increase of carbonyl in the oxidation process.

The synthesis and structural functionalization of 6-substituted 2,3-dihydroimidazo[2,1-b] [1,3]thiazol-5-ones

Aim. To extend the synthetic limits of the reaction of the electrophilic intramolecular cyclization (EIC) on the examples of 5,5-disubstituted and 5-yliden substituted 3-allyl-2-thiohydantoins and the directed structural modification of 2-halogenomethyl-2,3-dihydroimidazo[2,1-b][1,3]thiazole-5-ones obtained. Results and discussion. It has been found that the cyclization of 5,5-disubstituted and 5-yliden substituted 3-allyl-2-thiohydantoins under the effect of polyphosphoric acid (PPA), bromine and iodine is an effective method for the synthesis of new 2,3-dihydroimidazo[2,1-b][1,3]thiazole-5-ones. The reaction of the nucleophilic substitution of their 2-halogenomethyl representatives was used to obtain a number of sulfur-containing derivatives and azides. The latter were tested in the reaction of [3+2]-cycloaddition with N-phenylmaleinimide and propargyl alcohol. Experimental part. A series of 2-substituted 2,3-dihydroimidazo[2,1-b][1,3]thiazole-5-ones was synthesized by the reaction of 5,5-disubstituted and 5-yliden substituted 3-allyl-2-thiohydantoins with PPA and halogens with the yields of 66-96 %. A directed modification of the halogenomethyl group of imidazotiazolones produced a series of sulfur-containing derivatives and azides with the yields of 63-93 %. The azides synthesized were used in the [3+2]-cycloaddition reaction with N-phenylmaleinimide and propargyl alcohol leading to 1,2,3-triazoloderivatives with the yields of 51-85 %; their structure was confirmed by the complex spectral analysis. Conclusions. A convenient method for the synthesis of 2-halogenomethyl-substituted imidazo[2,1-b][1,3] thiazoles, which are effective reagents for the directed structural modification by sulfur- and nitrogen-containing functional groups, has been developed.

Effect of poly phosphoric acid (PPA) on creep response of base and polymer modified asphalt binders/mixtures at intermediate-low temperature

As an alternative to conventional polymer modifiers, poly phosphoric acid (PPA), presenting good compatibility with asphalt, has been proved to affect thermo-rheological properties of asphalt and its mixtures. In this paper, effect of poly phosphoric acid (PPA) on creep response of base, polymer (SBS, SBR) modified asphalt binders/mixtures at intermediate-low temperature were investigated by several tests. Bending beam rheometer test (BBR) and modified penetration test based on indention technique were used to measure intermediate and low temperature creep response of binders. Tensile stress restrained specimen test (TSRST) was applied to evaluate thermal cracking of mixtures. Results showed that addition of PPA slightly decreased creep stiffness of both base and polymer modified asphalt binder before aging, and accelerated aging level after short and long term aging. Modified penetration test indicated that creep rate change at intermediate temperature was slower after adding PPA, particularly for base binders whose creep rate declined a lot. In tensile stress restrained specimen test (TSRST), addition of PPA improved fracture strength and accelerated viscoelastic-elastic transition as well as weakened stress relaxation. Especially base asphalt mixtures cracked earlier and faster within a small temperature range after mixing PPA, which is undesired for low-temperature loading. Therefore PPA may have negative effect on asphalt mixtures and is more applicable with SBR and SBS modified asphalt with respect to low temperature performance.

Effect of polyphosphoric acid on physical properties, chemical composition and morphology of bitumen

The effect of polyphosphoric acid (PPA) on chemical composition, physical properties and morphology of bitumen was investigated. The morphology of the binders was characterized by atomic force microscopy. The results show that the influence of PPA on chemical composition, physical properties and morphology of bitumens depends on the base bitumen. The colloidal index shows an obvious effect on the chemical composition and physical properties as well as morphology of bitumen during PPA modification. A strong correlation is observed between morphology and chemical composition as well as physical properties for different bitumens after PPA modification.

Polyphosphoric Acid (PPA)-Modified Bitumen: Disruption of the Asphaltenes Network Based on the Reaction of Nonbasic Nitrogen with PPA

Relatively little is known about the effect of polyphosphoric acid (PPA) on bitumen chemistry and structure. In an effort to increase this understanding, the reaction of indole with PPA was studied by Fourier transform infrared spectroscopy (FTIR). Indole contains a pyrrole functional group very common in bitumen. The results revealed that both the amine and the double bond of indole can be reactive and that the indole concentration affected the reaction pathway. All reactions began with the protonation of the indole double bond, which provided two reactive carbocation intermediates. When the concentration of indole was high, each carbocation coupled with unprotonated indole and two products were obtained. In one case, two N−H groups produced a N−N bond, and in the other case, two indole double bonds produced a cyclobutane ring. When the concentration of indole was reduced by dilution, N−H coupling proceeded without double bonds coupling and a reaction with the PPA anion was found to occur instead. These ...

820. The effect of polyphosphoric acid on the α- and the β-form of 2-bromo-5-nitroacetophenone oxime

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