INNOVATIVE TESTS TO PREDICT THE STRENGTH AND TYPE OF ASPHALT-AGGREGATE BONDS

This paper discusses two techniques to characterize the type and measure the strength of asphalt-aggregate bonds. The Modified Lottman Test is commonly used to measure the physical strength of asphalt-aggregate bonds. Under certain conditions bonds may become weak due to chemical factors that are not accounted for in the Modified Lottman Test. In order to measure the chemical strength of the bond, a chemical preconditioning stage was introduced prior to performing the Modified Lottman Test. During this stage a compacted mix pill was exposed to an environment that was rich in either OH^-- or H^plus; ions. Such high or low pH conditions affect bonding reactions that are reversible in nature, and thereby expose the chemical weakness of the bond. Results show that different antistrip agents react differently to such conditions. The paper also discusses the effect of mix curing on bond strength under these limiting pH conditions. The other technique discussed in this paper, U a test that characterizes different aggregates in terms of their reactivity with aspnaltic components, which subsequently helps identify those aggregates that would form strong bonds with asphalt. It was observed that even within limestones aggregates, different types reacted to a different extent, and thereby, could be easily characterized     

Effects of the Asphalt Penetration Grade and the Mineralogical Composition on the Asphalt-aggregate Bond

This investigation analyzes the loss of bonding between the asphalt binder and the aggregate particles produced by water in hot-mix asphalt pavements. Three asphalt penetration grades were used: B35/50, B50/70, and B160/220. Four different types of aggregates were chosen due to their different expected stripping performances: hornfels, feldspathic schist, gabbro, and dolomitic calcite. To research the loss of adhesion, two laboratory test methods were compared: the rolling bottle method and the boiling water test. The results indicate that a higher asphalt-aggregate bond correlates to a lower asphalt penetration grade. To achieve significant asphalt-aggregate bond improvement, the difference between asphalt penetration grades must be noticeable.     

INVESTIGATION OF THE EFFECT OF AGGREGATE PRETREATMENT WITH ANTISTRIPPING AGENTS ON THE ASPHALT-AGGREGATE BOND

ABSTRACT

Addition of Chemical antistripping agents (ASA)to asphalt has inherent disadvantages such as reduction of the effectiveness of ASA in hot asphalt and formation of relatively weak bond with the aggregate surface. To circumvent such problems, a novel approach of aggregate pretreatment with ASA was investigated in this study. The aggregate was pretreated with aqueous emulsions/solutions of different organic surface modifiers. The effectiveness of this aggregate pretreatment procedure was evaluated to ascertain the asphalt-aggregate bond strength using the boiling water test. Boiling water test was selected for its rapidity and simplicity. The     

FLOW MICROCALORIMETRY AND SALI STUDIES OF THE ASPHALT/AGGREGATE INTERFACE

ABSTRACT

Sorption flow microcalorimetry methods were developed for measuring the amounts and heats of adsorption and desorption at the asphalt-aggregate interface. Model studies of the amounts and heats of phenylsulfoxide sorption on SHRP aggregates RH-greywacke and RC-McAdams limestone indicated strong and irreversible bonding of a large fraction of adsorbed phenylsulfoxide that resisted displacement by cyclohexane and water. In addition, the microcalorimetry results indicated that intermolccular interactions between adsorbed phenylsulfoxide molecules were very strong at submonolayer coverages. This suggests that phenylsulfoxide adsorbs with the sulfoxide directly attached and oriented perpendicular to the surface with strong face-to-face interactions of the phenyl groups. Similar experiments conducted on the sorption of SHRP asphalts AAD-1 and AAM-1 from solution on the RC and RH aggregates indicated significant differences in the sorption of these four asphalt-aggregate pairs. Similar to phenylsulfoxide, a large fraction of both asphalts adsorbed irreversibly with respect to cyclohexane and water-saturated cylohexane desorption. Surface analysis by laser ionization (SALI) was used to measure surface compositions of the aggregates and to monitor temperature programmed desorption (TPD) of adsorbed phenylsulfoxide. SALI analysis indicated that a significant fraction of die RC aggregate is covered with an aluminosilicate layer although bulk analysis indicates that this aggregate is predominantly limestone. TPD studies confirmed the microcalorimetry results that a large fraction of phenylsulfoxide irreversibly binds to silicate and aggregate surfaces and moreover that this irreversible binding leads to deoxygenation of the sulfoxide to sulfide at relatively low temperatures     

INVESTIGATION OF THE EFFECT OF AGGREGATE PRETREATMENT WITH ANTISTRIPPING AGENTS ON THE ASPHALT-AGGREGATE BOND

Addition of Chemical antistripping agents (ASA)to asphalt has inherent disadvantages such as reduction of the effectiveness of ASA in hot asphalt and formation of relatively weak bond with the aggregate surface. To circumvent such problems, a novel approach of aggregate pretreatment with ASA was investigated in this study. The aggregate was pretreated with aqueous emulsions/solutions of different organic surface modifiers. The effectiveness of this aggregate pretreatment procedure was evaluated to ascertain the asphalt-aggregate bond strength using the boiling water test. Boiling water test was selected for its rapidity and simplicity. The     

The Effect of Hydrated Lime on the Bond Between Asphalt and Recycled Concrete Aggregates

In this investigation, rolling bottle tests and boiling water tests were performed to evaluate the effect of hydrated lime on the adhesion between recycled concrete aggregates (RCA) and the asphalt binder. RCA from construction and demolition waste (C&DW) were used in this investigation. To generalize the findings, three asphalt penetration grades were analyzed: B40/50, B60/70, and B150/200. The results indicate that the use of hydrated lime does not improve the RCA-aggregate bond. Additionally, the results indicate that a higher asphalt-aggregate adhesion correlates to a lower asphalt penetration grade.     

MODEL STUDIES AND INTERPRETIVE REVIEW OF THE COMPETITIVE ADSORPTION AND WATER DISPLACEMENT OF PETROLEUM ASPHALT CHEMICAL FUNCTIONALITIES ON MINERAL AGGREGATE SURFACES

Moisture-induced damage in petroleum asphalt pavements, which results in a loss of pavement tensile strength, is a significant contributor to pavement performance problems such as rutting, shoving, flushing and cracking. Results of the present study provide fundamental information on some of the chemistries of moisture-induced damage. Model compounds containing polar chemical functional group types found in asphalts were used to simulate the adsorption-water displacement characteristics of asphalt molecules on mineral aggregate surfaces. A comparative and interpretative discussion of the model compound studies and earlier studies on actual asphalt-aggregate mixtures is presented. Carboxylic acids were confirmed as the functional type most strongly adsorbed on most mineral aggregate surfaces; however, they were also the functional type most easily water displaced. Pyridine-type functionality similar to that found in asphalts reduced the sensitivity of asphalt-aggregate mixtures to moisture damage. Results suggest that prior treatment of aggregates with antistripping agents rather than their prior addition to the asphalts should improve the moisture resistance of mixtures. The reaction of carboxylic acids with aggregate surfaces prior to the reaction of the aggregate surfaces with pyridine-type functionality greatly increased the sensitivity of the pyridine types to displacement by water. Also, the reaction of pyridine with carboxylic acid functionalities prior to their adsorption on aggregate surfaces also increased their sensitivity to water displacement. Results of the model compound studies provided further interpretation of the results of earlier fundamental studies on the adsorption and water displacement characteristics of actual asphalt components from aggregates typically used in paving mixtures. Results are interpreted with regard to their usefulness in finding pragmatic solutions to pavement pavement moisture damage problems. Further needed research is also suggested.     

沥青质分子聚集体中氢键作用力的研究

为研究沥青质分子聚集体中的氢键作用,用量子力学与分子动力学相结合的方法对形成沥青质分子聚集体中的氢键进行了研究。结果发现,沥青质分子中含有的N、S、O等杂原子是沥青质分子形成氢键的必要条件;沥青质分子聚集体形成单个氢键的键能较小,但聚集体中含有多个氢键时,其分子间的作用力会大幅增加。沥青质分子形成氢键的本质是由于H原子与杂原子的价层轨道电子进行叠加形成的,沥青质分子间有极少量的电子转移,导致形成弱的次级键; 在氢键作用中,起主要作用的是轨道相互作用能和色散作用能。     

AN EVALUATION OF OIL PRODUCED FROM ASPHALT RID (UTAH) TAB SAND AS A FEEDSTOCK FOR THE PRODUCTION OF ASPHALT AND TURBINE FUELS

Abstract

In this article an evaluation is made of the potential end uses of an oil produced from Asphalt Ridge tar sand by wet forward combustion. The oil is evaluated with respect to its potential to produce a specification-grade asphalt and aviation turbine fuels. To accomplish this the oil was vacuum distilled to produce a distillate and a residue. The distillation residue meets all of the ASTM D 3381 Table 1 specification tests for an AC-10 asphalt. However, the viscosity at 135°C (275°F) is low when compared with the more stringent D 3381 Table 2 requirements. This indicates that the residue has a higher temperature susceptibility than allowed for by Table 2. The residue also has an unusually low aging index. This indicates that it may not set properly. However, it may also mean that it may be resistant to rapid age hardening. The results from successive freeze-thaw cycling indicate that the residue, when coated on appropriate aggregates, is comparable to or better than some petroleum asphalts coated on the same aggregates. Freeze-thaw cycling to failure is an indirect measure of the resistance of an asphalt-aggregate mixture to moisture-induced loss of strength

The distillate of the thermally-produced oil which represents about 50 wt % of the whole oil was also evaluated as a feedstock for the production of transportation fuels. The chemical and physical properties of the distillate are improved with respect to those of the original bitumen and the thermally-produced oil. Combined gas chromatographic/mass spectral analysis of the neutral fraction from the distillate indicates it is composed of predominantly aromatic structures. The aromatic structures are primarily of the 2- and 3-     

AN EVALUATION OF OIL PRODUCED FROM ASPHALT RID (UTAH) TAB SAND AS A FEEDSTOCK FOR THE PRODUCTION OF ASPHALT AND TURBINE FUELS

In this article an evaluation is made of the potential end uses of an oil produced from Asphalt Ridge tar sand by wet forward combustion. The oil is evaluated with respect to its potential to produce a specification-grade asphalt and aviation turbine fuels. To accomplish this the oil was vacuum distilled to produce a distillate and a residue. The distillation residue meets all of the ASTM D 3381 Table 1 specification tests for an AC-10 asphalt. However, the viscosity at 135°C (275°F) is low when compared with the more stringent D 3381 Table 2 requirements. This indicates that the residue has a higher temperature susceptibility than allowed for by Table 2. The residue also has an unusually low aging index. This indicates that it may not set properly. However, it may also mean that it may be resistant to rapid age hardening. The results from successive freeze-thaw cycling indicate that the residue, when coated on appropriate aggregates, is comparable to or better than some petroleum asphalts coated on the same aggregates. Freeze-thaw cycling to failure is an indirect measure of the resistance of an asphalt-aggregate mixture to moisture-induced loss of strength

The distillate of the thermally-produced oil which represents about 50 wt % of the whole oil was also evaluated as a feedstock for the production of transportation fuels. The chemical and physical properties of the distillate are improved with respect to those of the original bitumen and the thermally-produced oil. Combined gas chromatographic/mass spectral analysis of the neutral fraction from the distillate indicates it is composed of predominantly aromatic structures. The aromatic structures are primarily of the 2- and 3-     

Hydrofining of heavy vacuum gas oil on modified alumina-nickel-molybdenum catalysts

Modified industrial alumina-nickel-molybdenum catalysts manufactured by OOO NZK have been tested in the mode of hydrotreating of heavy vacuum gas oil on a pilot plant of OAO Middle Volga Research Institute of Oil Refining (OAO SvNIINP). A change in hydrocarbon-type and structural-group composition of gas oils during the hydrogen treatment process has been considered. It has been found that hydrotreating on the GR-24M, NKYu-300, and NKYu-330 catalysts under the examined conditions (340?C400°C, 4.0 MPa, 0.5?C1 h^?1, hydrogen: feedstock ratio of 500?C800: 1 Nm³/m³) leads to a reduction in sulfur, nitrogen, and metal contents of the gas oil and to saturation of polyaromatic compounds with hydrogen, thereby facilitating the further destruction of the feedstock in a catalytic cracker.     

Influence of asphalt chemical composition on moisture susceptibility of asphalt mixtures

To evaluate sensitivity of moisture damage resistance with chemical composition of asphalt, the adhesion energy, debonding energy as well as compatibility ratio of 69 asphalt-aggregate combinations were calculated with thermodynamical models. Pearson correlation analysis and regression analysis were carried out to correlate the relationships between asphalt chemical composition (saturates, aromatics, resins, asphaltenes, and wax) and moisture stability of asphalt mixture. The results showed that more resins and less asphaltenes in asphalt could lead to better moisture stability of asphalt mixture under dry and wet conditions, which can be effectively predicted by multiple regression models with different asphalt chemical components.     

Adhesion of Recycled Concrete Aggregates,Demolition Debris,and Asphalt

In this investigation, rolling bottle tests and boiling water tests were conducted to evaluate the effect of different fillers and treatments on the adhesion between recycled concrete aggregates (RCA) and asphalt. The test results when 100% RCA loose mixtures were evaluated indicated that the filler that achieves the best asphalt aggregate bond was grey Portland cement. Curing the mixture in an oven for 4 h at mix temperature before compacting and coating RCA with bitumen emulsion are treatments that achieved satisfactory adhesion results as well.     

The mechanism of inhibited oxidation of norbornene series bicycloolefins

The kinetics of oxidation (323 K) of bicycloolefins from the norbornene series: norbornene, vinylnorbornene, ethylidenenorbornene, and norbornadiene, inhibited by phenols (PhOH), aromatic amines (AmH), transition metal compounds (Me ⁿ ), or stable nitroxyl radicals of the piperidine series (>NO^·), in chlorobenzene solutions have been studied. It has been found that the phenols are single-action inhibitors, whereas the amines, the transition metals, and the nitroxyl radicals repeatedly terminate oxidation chains. The results are explained in terms of phenomenology of the bicycloolefin oxidation process associated with the fact that peroxide radicals attack different reaction centers (π- and α-CH bonds), thereby resulting in the formation of different types of chain carrier radicals: low-molecular-weight hydroperoxide and polyperoxide radicals.     

Tack coats for asphalt paving

Poor bonding between two layers of hot mix asphalt (HMA) is the cause of many highway pavement problems. Normally, hot asphalt cements, emulsified asphalts or cutback asphalts are used as tack coat. The objective of this study was to evaluate the practice of using tack coat through controlled laboratory simple shear tests and determine the optimum application rate. The influences of tack coat types, application rates, viscosity and temperatures on the interface shear strength were examined. Test results indicated that latex modified asphalt emulsion has the highest interface bond strength. It was also found that applying low viscosity tack coat asphalt emulsion at two layers is more effective than a tack coat asphalt emulsion high viscosity one layer coat.     

油基钻井液性能与固井质量研究

为了研究油基钻井液性能和固井质量之间的直接关系，采用新建立的评价方法--人工岩心法，考察了油基钻井液体系及其主要组分对固井作业中第一、第二界面剪切胶结强度的影响规律，以及不同混浆比例下对水泥浆胶凝强度、初凝时间、终凝时间和水泥石抗压强度的影响规律。研究表明：对两界面胶结强度的影响由大到小依次是体系、乳状液、主乳化剂、降滤失剂、白油；前置液清洗后，胶结强度成倍提高，尤其对体系、乳状液和降滤失剂清洗效果最佳；随混浆比的增大，水泥浆初凝和终凝时间明显延长，水泥石抗压强度明显下降，甚至不凝。     

13C NMR STUDIES ON ROADWAY ASPHALTS

ABSTRACT

Roadway asphalt has been characterized by ¹³C NMR and reasonable chemical shift assignments made. An initial analysis of the asphalt samples from the refinery liquid, plant mix. Initial and 18 month cores has been made; however, these roadways have not aged sufficiently to develop correlations with performance.     

润滑油基础油氧化链引发反应机理的分子模拟

Chain initiation reactions in the oxidation process of lubricant base stock molecules were studied by molecular simulations. Two ways to initiate lubricant oxidation were investigated. They were the dissociation of chemical bonds in base stock molecules and the reaction between base stock molecules and oxygen (O2), respectively. Reaction activation energies of above methods were calculated. The results show that C—C bonds are more likely to break than C—H bonds to generate free radicals by the pyrolysis of chemical bonds. The C—C bonds with tertiary carbon atoms are preferential positions to crack. However, bond dissociation energies of them are above 360 kJ/mol, which are difficult to occur under lubricant working conditions. The chain initiation is more likely to occur by the way that O2 attacks the two atoms in C—H bonds at the same time, and embeds into the C—H bond to produce hydrocarbon peroxides. And then, the O—O bond is cracked to form hydroxyl radicals and alkoxy radicals. The C—H bonds with tertiary carbon atoms are the preferential reaction sites, whose reaction activation energy is about 190.11 kJ/mol.     

Asphaltene Self-Association: Modeling and Effect of Fractionation With A Polar Solvent

Abstract

The self-association of asphaltenes in toluene is believed to occur step-wise, rather than by the formation of micelles. A number of step-wise models have been used to fit the calorimetric titration of asphaltenes in dried toluene solutions, with excellent results. All the models are based on chemical reactions equivalent to the ones found in polymerization. The study shows that the choice of the average properties of asphaltenes, such as the molecular weight, is critical in the final value of the parameter of interest, namely the average heat of self-association ΔH _a . The low values of ΔH _a obtained suggest that a fraction of asphaltenes is not active in the calorimetric experiments. Asphaltenes from Venezuela (LM1) and Mexico (KU) have been fractionated by precipitation with a mixture of acetone and toluene. It is considered that the most polar compounds are collected in the soluble fraction. A calorimetry study was performed on the two fractions, and the results show that the soluble fraction (SOL) has a much higher heat developed than the insoluble fraction (INS). This suggests again that a fraction of asphaltenes is not active in the calorimetric experiments, either because it does not self-associate or because the dilution effect is not strong enough to break the aggregates. Fluorescence and IR spectroscopy experiments confirm there is self-association in INS fraction, leading to the conclusion that asphaltene aggregates are formed by bonds of different strengths. The stronger aggregates would be predominantly in INS fraction and would be inactive in the calorimetric experiments.     

New heavy aggregate for offshore petroleum pipeline concrete coating Central West Sinai,Egypt

In this paper the local materials used in concrete mix are studied in a manner that they can resist the aggressive marine environment and mechanical damage, which can occur at several stages during transportation, construction and installation of the pipelines. In earlier studies we succeeded in finding the Egyptian ilmenite ore adequate for concrete weight coating and already utilized for many pipeline projects in Egypt. According to the presence of about 30% titanium oxides in ilmenite composition which may be extracted to be used in others strategically fields, the object of this paper is to study and evaluate the mechanical, chemical and physical properties of another local hematite high density iron ore to be used in subsea concrete weight coating for offshore petroleum pipelines. The results indicate that the local material of Um Bogma hematite iron ore can substitute both imported iron ore and local ilmenite from Abu Ghalaga in this field to reduce the cost effective and increased economical value of local ores. Laboratory and field tests were conducted for the hematite ore forming a concrete mix, composed of hematite ore, cement and fresh water according to international concrete coating specification requirements, the ore produces a concrete mix with 190–195 pcf minimum dry density and compressive strength, after 28 days of hydration, varying from 40 to 45 N/mm² (400–450 kg/cm²) which comply with the international standards and specifications of submarine petroleum pipeline coating. In addition, local hematite shows superior results than local ilmenite and achieves 190 pcf instead of 180 pcf in case of using ilmenite.