Binder Source Research Articles

Long-term aging effect on rheological properties of combined binders from various polymers with ground tire rubber

The objective of this study is to evaluate the long-term aging effect on the rheological properties of the modified PG 76-22/PG 76-16 binders produced from ground tire rubber (GTR) with various polymers after a long-term aging process. The tests included the investigation of G*sinδ, phase angle, amplitude sweep, frequency sweep, creep and creep recovery and stress relaxation in terms of three base binders and five polymers. The test results indicated that both base binder and polymer type affect the fatigue resistance, creep and creep recovery, viscoelastic property, and relaxation characteristic of each modified binder. In addition, terminally blended GTR binder has better fatigue resistance than laboratory blended GTR binder after a long-term aging procedure in this study. It seems that binders modified with polyphosphoric acid combined with 7% GTR exhibit more elastic properties and better rheological properties than other modified binders regardless of binder sources.

Eco-friendly Materials for a New Concept of Asphalt Pavement

It is estimated that more than 90% of the 5.2 million kilometers of European paved roads and highways are surfaced with asphalt. Also, about 44% of goods are transported by road in the EU; maintaining their condition whilst in transit is crucial for the economy.The construction of a new road has a number of implications for the environment, consuming large amount of materials and energy. Also, the price of crude oil, which is the major source of bituminous binder, has significantly increased in recent years (the most noticeably in 2001–2008). This has led to an increase in the total price of asphalt mixtures.In order to promote sustainable practices and to combat price increase, measures with sound sustainability credentials need to be widely implemented. Developing novel materials and technologies to integrate greener material, waste and recycled materials into the production cycle of asphalt mixtures is a solution that improves both sustainability and cost-efficiency of the asphalt pavement industry.The main concept presented in this paper is the application of an eco-innovative asphalt pavement designed through partial substitution of greener materials into asphalt mixtures: reclaimed asphalt pavement (RAP), construction and demolition waste (C&DW), lignin (by-product of 2nd generation bioethanol processing) and bio-binder from vegetable oil. This paper discusses a new concept of an asphalt pavement structure with ecologically oriented attributes, achieved whilst maintaining a level of long term performance comparable or greater than that of conventional pavement structures.The two main components of asphalt mixture – bitumen and aggregates – are focused upon. In relation to bitumen, two methods to ‘green’ the fresh binder fraction are explored: The first investigates bio-fluxing bitumen, which enables part of the petro-chemical binder to be replaced with bio-based products; the second uses a specific industrial waste, also bio-derived, to replace the crude-oil derived polymer in modified bitumen. In relation to aggregates, two different approaches are also explored: The use of high rates of reclaimed asphalt pavement (RAP) in new hot asphalt mixtures, thanks to the addition of bio-fluxing agents which will allow working at lower temperatures, and the use of construction and demolition waste (C&DW). Optimal integration of C&DW as raw material will be established using a selective process for the separation of C&DW to increase the overall quality of the recycled aggregates.Considering the full pavement structure, the main innovations can be summarized as follows: (A) in surface course is the introduction of green bitumen modifier, derived from recovered waste bioethanol production as an alternative to the traditional additives used for polymer modification; (B) in binder and base course, bio-fluxing agents allow for the integration of higher percentage of reclaimed asphalt; and (C) the lower layers (sub-base and subgrade) are mainly composed of materials derived from construction and demolition waste.This paper describes the systematic approach for selecting the right combination of these main pavement components in the design of asphalt mixtures, from laboratory tests to real applications. This approach has been developed by a consortium of partners in the FP7 funded Asphalt Pavements for a Sustainable Environment (APSE) project.

Mg(OH)2 Nucleation and Growth Parameters Applicable for the Development of MgO‐Based Refractory Castables

MgO is a very attractive raw material for refractory applications. However, its use has been mainly aimed at developing high‐magnesia and magnesia–carbon bricks due to the marked hydration likelihood of this oxide and the related drawbacks (volumetric expansion, crack formation) associated with this transformation. This work aims to evaluate some critical aspects that affect the MgO reaction with water (magnesia source, particle size, concentration of available sites for brucite nucleation, influence of a hydrating additive – acetic acid, and others) during the curing and drying steps of Al2O3–MgO binder‐free refractory castables. The attained experimental results were associated with the boundary nucleation and growth model proposed in the literature. According to the in situ elastic modulus measurements carried out at 110°C, the MgO particle size and reactivity present an important effect on the nucleation and growth of brucite crystals, highlighting that a proper site activation should be induced during the castables' curing process in order to effectively allow the use of magnesia as a binder source for refractories. Faster Mg(OH)2 nuclei generation also helps to minimize further growth of these crystals, leading to a decrease in the samples' porosity and, consequently, a continuous increase in the overall refractory stiffness (E values).

Significance of pH Variance in Predicting Chemical Reaction in Hot Mix Asphalt

AbstractHot mix asphalt (HMA) is a combination of siliceous, calcareous, or intermediate aggregate materials from selected sources, blended with formulated asphalt binders from various asphalt binder producers. These components are modified by additional additives to enhance the bonding of the binders and aggregates. Concern over moisture damage (stripping), defined as the loss of strength and durability in asphalt mixtures when the binder separates from the aggregate, has prompted years of research into a variety of failure mechanisms. Prominent in these failure mechanisms is the pH at the binder–aggregate interface. This technical paper addresses the pH variance of individual components and loose blended HMA mixes from 17 selected material sources and 2 asphalt binder sources to assess the pH of any chemical reactivity. The main objective of the paper is to determine whether pH variances of individual components or mixed HMA materials (asphalt binder, aggregate, and additives) point to suspect component...

Rheological characteristics investigation of high percentage RAP binders with WMA technology at various aging states

The application of reclaimed asphalt pavement (RAP) is very promising and the research activities focusing on this subject is numerous in recent year. However, how to increase the percentage of RAP in the surface layer mixtures of asphalt pavement and meet or exceed the standards is challenging to the state highway agencies in the USA. The objective of this study is to explore the rheological properties of the high percentage (up to 50%) of RAP binder with three base binders in terms of five RAP binder content, two RAP binder sources, one HMA and one warm mix additive (WMA) technologies at three aging states. The viscosity, failure temperature, rutting resistance, fatigue resistance of various asphalt binders were tested in this study. The results indicated that the combined binders after a short term aging and a long term aging procedures still satisfied the requirement of asphalt binder set by Superpave binder specifications. In addition, increasing the RAP binder concentration could improve the rutting resistance of asphalt binder but a reduction in the fatigue resistance was noticed. However, the WMA additive could offset these properties of combined binder. Moreover, the results indicated that the RAP source typically affected the performance properties of combined asphalt binder and should be investigated individually.

Rheology investigation of combined binders from various polymers with GTR under a short term aging process

Many polymers have popularly been used in asphalt paving industry to improve the resistances of rutting, fatigue, low temperature cracking and etc. Using a low percentage of ground tire rubber (GTR) with other polymers to reduce the cost of modified binder is interesting for some researchers. In the present study, the objective was to conduct a rheological investigation of combined binders after a short term aging process at high performance temperatures. The conventional testing procedures including dynamic shear rheometer (DSR) and related properties such as failure temperature, G∗/sinδ, viscous flow, creep and creep recovery, amplitude sweep and frequency sweep as well as stress relaxation were performed to determine the influences of polymer type and binder source on the rheological characteristics. The experimental design included three base binders and five polymers. The test results indicated that, to produce PG 76 binder by modifying 7% GTR and other polymers are feasible and the base binder and polymer type affect the creep and creep recovery behaviors, viscoelastic properties, and relaxation characteristics of each modified binder. In addition, terminally blended GTR binder and laboratory blended GTR binder generally have some different trends with terminally blend styrene butadiene styrene (SBS) binder in this study but exhibit similar good performance properties after a short term aging procedure, thus were recommended to use in the field.

Identification of structure-activity relationships from screening a structurally compact DNA-encoded chemical library.

Methods for the rapid and inexpensive discovery of hit compounds are essential for pharmaceutical research and DNA-encoded chemical libraries represent promising tools for this purpose. We here report on the design and synthesis of DAL-100K, a DNA-encoded chemical library containing 103 200 structurally compact compounds. Affinity screening experiments and DNA-sequencing analysis provided ligands with nanomolar affinities to several proteins, including prostate-specific membrane antigen and tankyrase 1. Correlations of sequence counts with binding affinities and potencies of enzyme inhibition were observed and enabled the identification of structural features critical for activity. These results indicate that libraries of this type represent a useful source of small-molecule binders for target proteins of pharmaceutical interest and information on structural features important for binding.

Rheology evaluations of WMA binders using ultraviolet and PAV aging procedures

Oxidation of an asphalt binder affects the long term performance of an asphalt pavement, especially under thermal and/or ultraviolet (UV) radiation conditions. The objective of this study is to investigate the rheological behaviors of various WMA binders after long term UV aging and conventional PAV aging procedures. The following rheological properties were tested and evaluated in this study: complex shear modulus, phase angle, elastic modulus, viscous modulus at an intermediate service temperature, and deflection, stiffness, and m-value at a low temperature. The experimental design included four asphalt binder sources (two grades); four WMA additives and control. Two aging methods of UV and PAV aging were utilized and a total of 40binders were tested and evaluated. The test results indicated that UV and PAV aging procedures are significantly affected by asphalt binder source and grade. In addition, WMA additives generally have no influences on rheological properties of UV and PAV aged binders. Moreover, the differences in deflection, creep stiffness, and m-values of UV and PAV aged binders are generally not affected by their grade, source and WMA additives. Therefore, UV aging procedure used in this study may be an effective method in investigating rheological characteristics of WMA binder after a long term aging process.

Wetting Characteristics of Asphalt Binders at Mixing Temperatures

Conventional hot-mix asphalt is produced by heating the aggregate and the asphalt binder to elevated temperatures, typically within the range of 140°C to 170°C. These temperatures ensure that the viscosity of the asphalt binder is low enough to coat the aggregate particles effectively. During the past decade, warm-mix asphalt (WMA) technology has been introduced to reduce the mixing temperatures by approximately 30°C compared with hot-mix asphalt. Workability at these reduced temperatures typically is achieved by the use of chemical additives in the asphalt binder or through the foaming of the asphalt binder with small percentages of water. In either case (i.e., WMA or hot-mix asphalt), one of the important physical properties that dictates the quality of coating and concomitant aggregate–binder bonding is the surface tension of the asphalt binder at mixing temperatures. In this study, the surface tension of different liquid asphalt binders was measured at typical mixing temperatures. The influence on the surface tension of binder type, temperature, and chemical additives used to produce WMA was evaluated. The results showed that the surface tension of asphalt binder depended on the rate of surface formation, temperature, and the source of the asphalt binder. The dynamic surface tension of the asphalt binders suggested that inherently they behaved similarly to surfactants. This observation lent indirect support to the theory that different molecular species tended to agglomerate within the binder, which rendered the binder microstructurally heterogeneous. Only one of the chemical additives resulted in a significant reduction in the surface tension of the binder compared with the control.

Developing nano-bonded refractory castables with enhanced green mechanical properties

Applying colloidal silica suspensions as a binder source for refractory castables has been of great interest in recent years. Nevertheless, the resultant low green mechanical strength of these castables has hindered their application in relevant areas. The current paper provides a novel engineering route to improve the mechanical properties of colloidal silica bonded castables before firing. In order to attain this target, small amounts of calcium aluminate cement (CAC) and/or hydratable alumina (HA) were used as gelling agents. A splitting tensile test showed that although using HA resulted in a more significant increase in the modulus of rupture of the samples when compared to CAC, mixing both (CAC+HA) had the most positive impact on the green mechanical properties of the castables, leading to strength levels as high as the reference cement-bonded system (CAC-Ref). XRD and DTG tests were carried out to evaluate the hydration behavior of the selected additives. The results indicated that CAC enhanced the hydration of HA based on the accelerated dissolution of the gel layer formed on HA particles, which was induced by the Al(OH)4− common ion effect. The proposed mechanism was confirmed by a specific conductivity test. Additionally, 29Si solid state NMR spectroscopy was used to determine the effect of the dual additive system (HA+CAC) on the siloxane bond formation. Quantification of Q2, Q3 and Q4 species in alumina–colloidal silica suspensions containing HA, CAC or HA+CAC highlighted that the improved green strength is mainly related to a more effective hydration of HA. Based on the NMR and XHR SEM analyses, HA can be considered as an alternative gelling agent for nano-bonded refractory castables.

Quality-by-design III: application of near-infrared spectroscopy to monitor roller compaction in-process and product quality attributes of immediate release tablets.

The objective of this study is to use near-infrared spectroscopy (NIRS) coupled with multivariate chemometric models to monitor granule and tablet quality attributes in the formulation development and manufacturing of ciprofloxacin hydrochloride (CIP) immediate release tablets. Critical roller compaction process parameters, compression force (CFt), and formulation variables identified from our earlier studies were evaluated in more detail. Multivariate principal component analysis (PCA) and partial least square (PLS) models were developed during the development stage and used as a control tool to predict the quality of granules and tablets. Validated models were used to monitor and control batches manufactured at different sites to assess their robustness to change. The results showed that roll pressure (RP) and CFt played a critical role in the quality of the granules and the finished product within the range tested. Replacing binder source did not statistically influence the quality attributes of the granules and tablets. However, lubricant type has significantly impacted the granule size. Blend uniformity, crushing force, disintegration time during the manufacturing was predicted using validated PLS regression models with acceptable standard error of prediction (SEP) values, whereas the models resulted in higher SEP for batches obtained from different manufacturing site. From this study, we were able to identify critical factors which could impact the quality attributes of the CIP IR tablets. In summary, we demonstrated the ability of near-infrared spectroscopy coupled with chemometrics as a powerful tool to monitor critical quality attributes (CQA) identified during formulation development.

Evaluation of the Rheological Properties and Activation Energy of Virgin and Recovered Asphalt Binder Blends

AbstractIn this study, the rheological properties and activation energy (AE) of unaged and aged asphalts blended with different percentages of binder, recovered from three reclaimed asphalt pavement (RAP) sources, were investigated. Superpave asphalt binder tests were used to evaluate the effects of the recovered asphalt binder source and content. The results indicated that the addition of recovered binder from each source increased the viscosity, G*/sinδ, and G*sinδ. The increase in viscosity per 1% recovered binder was evaluated using non-dimensional viscosity index (∇ηRAP). In addition, the increase in G*/sinδ and G*sinδ per 1% recovered binder were investigated using relative Superpave rutting gradient (RSRG) and relative G*sinδ gradient (RG) factors, respectively. The results indicated that the ∇ηRAP, RSRG, and RG depended on recovered binder source, content, aging, and test temperature. The interpretation of the AE results depended on the physical phase of the asphalt blends, irrespective of the rec...

An evaluation of reclaimed asphalt shingles in hot mix asphalt by varying sources and quantity of reclaimed asphalt shingles

The practice of incorporating reclaimed asphalt pavement (RAP) into hot mix asphalt (HMA) is common within the paving industry as a cost-effective source of quality paving binder and aggregate. Recently, research efforts have focussed on investigating the potential of using reclaimed asphalt shingles (RAS) in HMA. This study provides a comparison of the laboratory performance of several HMA mixtures with varied RAS sources and contents. Performance testing for the mixtures included dynamic modulus and phase angle. Fatigue testing was also performed for several of the mixtures. Mixtures with higher amounts of binder replacement from RAS showed stiffer performance at high temperatures and less stiff performance at low temperatures. The mixture with greater amounts of RAS showed better fatigue performance. The mixtures with various sources of RAS, whether pre- or post-consumer, showed similar low-temperature performance, while the mixture with a blend of both sources was stiffest at high temperatures. A set of mixtures comparing different RAS sources was also compared with a mixture containing RAP as the only recycled binder source. The results of testing of these mixtures showed that the RAP mix was stiffer at intermediate and high temperatures but had similar results to the RAS mixtures in low-temperature performance.

A long-term ultraviolet aging effect on rheology of WMA binders

Asphalt binder is generally easy to age in the field, especially under thermal and/or ultraviolet (UV) radiation conditions. Current asphalt performance evaluation system gives limited consideration to UV aging, especially, as using warm mix asphalt (WMA) technologies. The objective of this study is to investigate the influence of long-term UV aging on rheology of various WMA binders. The following rheological properties were tested and evaluated in this study: viscous flow, performance grade, creep and creep recovery, amplitude and frequency sweep tests. The experimental design included four asphalt binder sources and two grades; four WMA additives (Cecabase-RT, Evotherm, Rediset, and Sasobit) and control. A total of 20 binders were tested. The test results indicated that a UV aging procedure generally had obvious effect on the complex modulus and phase angle values of various UV aged WMA binders. Their viscosity values were generally different since the WMA additive or binder source played a key role. Moreover, creep and creep recovery generally showed a similar trend for various WMA binders. Similarly, the amplitude and frequency sweep values exhibited a similar trend for various WMA binders but these values were different for various binder sources and grades. Therefore, it is necessary to explore the rheological properties of WMA binders after a long term UV aging procedure in the lab.

Selecting Warm Mix Asphalt (WMA) Additives by the Properties of WMA Binders

The objective of this research was to investigate the influence of WMA additives on the properties of WMA binders through a series of laboratory testing such as viscosity, penetration, ductility, and softening points on the binders. The experimental design included the use of three WMA additives of Sasobit, Rediset, and Evotherm at a recommended content of 2, 2 and 0.6% respectively, two base binder sources, and one modified binder sources. The properties of WMA binders were compared to those of original asphalts without the additives as controls. Results from this study showed that: (1) Three WMA additives of Sasobit, Evotherm and Rediset increased the dynamic viscosity (60°C) of asphalt binders; (2) The additives of Evotherm and Rediset reduced the kinematic viscosity (130°C) of tested WMA asphalt binders. Adding 2 % Sasobit did not affect the kinematic viscosity; (3) Adding 2 % Sasobit reduced the penetration of WMA asphalt binder obviously. The most reduced rate of penetration is 22.7 % for SK base asphalt binder; (4) The WMA additives increased the softening point of WMA asphalt binders, except for the case with 0.6 % Evotherm. The effect of adding 2% Sasobit on the softening point of asphalt binders is the most significant, while the effect of adding 0.6 % Evotherm is the least; (5) adding 0.6 % Evotherm increased the ductility of warm asphalt binders by 28.6 %, while adding 2 % Sasobit reduced the ductility of warm asphalt binders obviously.

Mullite-based refractory castable engineering for the petrochemical industry

Abstract Refractory castables used in fluid catalytic converter (FCC) risers should present suitable particle erosion and thermal shock resistances at temperatures below 900 °C. Considering that calcium aluminate cement (CAC)-bonded refractories usually start their densification above 1200 °C, the use of sintering additives to induce faster densification is a promising technological alternative. Therefore, this work addresses the evaluation of mullite-based castables containing a boron-based sintering additive and CAC and/or hydratable alumina as the binder sources. Hot elastic modulus, cyclical thermal shock, hot modulus of rupture and cold erosion resistance measurements were carried out to evaluate the compositions. According to the attained results, adding 1.5 wt% of the evaluated sintering additive to the designed castables led to a remarkable increase of the hot modulus of rupture (maximum of 40.4 MPa at 800 °C for the CAC-containing refractory) and high erosion resistance (1.5–2.9 cm3) after pre-firing at 800 °C for 5 h. Moreover, the combination of CAC and hydratable alumina gave rise to an improved refractory (M–2CAC–2HA–S) showing a transient liquid formation at an increased temperature, high thermal shock resistance (no E decay after 8 thermal cycles, ΔT=800 °C) and high mechanical strength at 800 °C and 1000 °C.

Evaluation of self healing properties of bituminous binders taking into account steric hardening effects

Steric hardening is a time dependent phenomenon thatτ can affect the healing properties of bituminous binders. In the experimental investigation reported in this paper, the rheological test method proposed for the evaluation of healing involved the use of a prolonged rest period included between two continuous oscillatory loading phases. A simple model was developed to subtract the contribution of steric hardening to the total stiffness gain attained during rest and thus to evaluate the recovery in mechanical properties due to self healing only. Analysis of the results indicated that cumulated damage of binders is composed by a reversible and a non reversible part. True self healing potential of the materials, as evaluated by means of the relative reversible damage index (RRD) and the relative index of fatigue life increase (RFIHEALING), was found to be a function of imposed damage, binder source and polymer modification.

Effects of Warm Mix Asphalt (WMA) Additives on the Properties of WMA Mixtures

The objective of this research was to investigate the influence of Warm Mix Asphalt (WMA) additives on asphalt mixture properties through the laboratory testing programs such as air voids, tensile strength ratio (TSR), dynamic stability, and low temperature bending failure strain tests. The experimental design included the use of three WMA additives of Sasobit, Evotherm and Rediset, one base (unmodified) binder source, and one modified binder source. The WMA mixtures were compared to those of controls, i.e., mixtures without the additives. Results from this study showed that: (1) WMA mixtures with Rediset, Evotherm, and Sasobit had slightly higher air voids than Hot Mix Asphalt （HMA）; (2) All WMA mixtures with SBS modified asphalt have lower TSR values than the original ones. The TSR of the WMA mixtures with base (unmodified) asphalt is not significantly different from HMA; (3) The WMA mixtures with SBS modified asphalt have lower values of the dynamic stability and bending failure strain than HMA, while the WMA mixtures with base asphalt are contrary, except with Rediset additives.

Significance of Mixture Parameters on Binder Aging in Hot-Mix Asphalt Mixtures

Traditionally, aging studies of asphalt materials have been conducted primarily on asphalt binders only and have omitted any potential influence of the aggregate. These results are commonly extrapolated to the mixture behavior without a comprehensive understanding of how the mixture characteristics may potentially influence the aging of the binder within the mixture. This study was initiated by FHWA to evaluate the effects of mixture parameters—namely, different aggregate and asphalt binder sources, air voids, and binder contents—on the aging characteristics of asphalt binders aged in mixtures. Those same binders were also aged in pressure aging vessel (PAV) pans in laboratory ovens to determine the aging characteristics of the asphalt binders, as is the current state of practice. These characteristics were determined by the binder kinetics, with respect to the carbonyl area measured from the Fourier transform infrared spectroscopy spectra as a function of aging time and temperature. The hardening susceptibility (HS) of the asphalt binders, as defined by the relationship between the low shear viscosity and the carbonyl area, was also determined. The HS of the asphalt binders aged in the mixtures was compared with the HS of the binders aged in the PAV pans and was found to be statistically dissimilar for some mixtures and statistically similar for others. The analysis revealed that the effective binder content of the mixtures provided the strongest indicator of whether the evaluated mixture parameters would have a significant influence on the aging characteristics of the asphalt binder in the mix.

Laboratory investigation of moisture susceptibility of long-term saturated warm mix asphalt mixtures

Moisture damage in flexible pavements might cause stripping in asphalt pavements and ultimately result in premature failure. Warm mix asphalt (WMA) technology as a means to decrease the energy consumption and emissions associated with conventional hot mix asphalt production is broadly being used recently. However, the utilisation of the hydrated lime and liquid anti-strip additives in WMA mixtures makes these issues more complicated. The objective of this study was to investigate and evaluate the moisture susceptibility of mixtures containing anti-stripping agents (ASAs) and WMA additives after long-term saturated durations. The experimental design for this study included the utilisations of one binder source (PG 64-22), three ASA additives and control, two WMA additives and hot mix, and three aggregate sources. A total of 36 types of mixtures and 540 specimens were fabricated and tested in this study. The performed properties included indirect tensile strength (ITS), tensile strength ratio, flow and toughness. The results indicated that the aggregate source has an effect on dry ITS and flow values but had no effect on wet ITS, wet flow and toughness values. In addition, hot mixture generally had higher dry and wet ITS values, and there were significant differences in flow and toughness values between hot and warm mixtures. Moreover, the hydrated lime exhibited the best moisture resistance in WMA mixtures; the liquid ASA additives could increase the ITS values of mixtures but exhibited a weak moisture resistance in this study. Furthermore, the storage and saturated duration generally had no effect on ITS values, and statistical analysis results did not show any differences among these mixtures.