Effect Of Anti-stripping Additives Research Articles

Applying asphalt binder modifier in reducing moisture-induced damage of asphalt mixtures

In this study, it has been attempted to use thermodynamics theories and the surface free energy (SFE) method to evaluate the effect of anti-stripping additives on the asphalt binder cohesion and asphalt binder–aggregate adhesion under dry and wet conditions. Two types of aggregate, granite and limestone, AC 60–70 and two additives (a polar copolymer and an ethylene copolymer with mineral asphalt binder) used are among the materials used in this study. The results indicate that the use of both types of polymer has increased the cohesion of the asphalt binder and reduced failure in the asphalt binder film. The results show that the polar copolymer increases the basic components and decreases acidic component of the asphalt binder surface free energy that increases the adhesion with acidic aggregates that are susceptible to moisture-induced damage. Ethylene copolymer material also increased the asphalt binder surface free energy that strengthens the non-polar asphalt binder–aggregate bonds. Both polymer materials have reduced the separated free energy and increased the adhesion free energy that reduces the desire for the stripping process in the asphalt mixture. The results of mechanical tests also show that the use of polymeric additives has improved the asphalt mixtures strength against moisture-induced damage.

Investigate the effect of using polymeric anti-stripping additives on moisture damage of hot mix asphalt

Moisture damage in asphalt mixtures can be defined as the loss of durability and strength caused by the effect of moisture. In order to improve the strength of asphalt mixtures against this damage, anti-stripping additives are used to increase the aggregate-asphalt binder adhesion and cohesion. In this study, the influence of Polybutylene on the moisture susceptibility of asphalt mixtures is investigated. To evaluate the effects of anti-stripping additives on the specimens made with granite and limestone aggregates, the indirect tensile strength ratio test and the theoretical concepts of surface free energy have been used. The results of the mechanical tests indicated that the PB additive has increased the strength of the asphalt mixtures against moisture damage. The results of the SFE method also indicated that Polybutylene additive improved the adhesion between asphalt binders and acidic aggregates which were susceptible to moisture damage. Also, using Polybutylene increased the cohesion free energy, which increased the asphalt binder film strength against cohesion failure. Moreover, the calculations based on thermodynamic concepts indicated that the asphalt binder modification has reduced the debonding energy, which also represented the reduced tendency of the system to stripping.

Novel Method for Moisture Susceptibility and Rutting Evaluation Using Hamburg Wheel Tracking Test

The Hamburg wheel tracking test (HWTT) has been widely used as a standard laboratory test to evaluate the moisture susceptibility and rutting resistance of asphalt mixtures. The stripping infection point and the rut depth at a certain number of load cycles are two common parameters obtained from the test. Although these parameters have been widely adopted by several transportation agencies, the accuracy and variability in characterizing mixture properties of these parameters have been questioned. In this study, a novel method to analyze the HWTT results is introduced and three new parameters are proposed to measure the moisture susceptibility and rutting resistance of asphalt mixtures. The new parameters are compared against the current ones to assess their capability to discriminate between three types of asphalt mixtures with different performance results in the HWTT. Significant advantages in characterizing mixture resistance to stripping and rutting are demonstrated by the new parameters. In addition, the effect of antistripping additives and recycled materials on mixture performance in the HWTT is evaluated with mixtures from a field project in Texas. Test results for the new parameters show that the addition of antistripping additives improves the susceptibility of asphalt mixtures to moisture. Specifically, the use of lime is more beneficial for improving mixture performance than a liquid antistripping agent. Conversely, the addition of recycled materials provides mixtures with increased moisture susceptibility but improved rutting resistance.

Laboratory evaluation of the effect of nano-organosilane anti-stripping additive on the moisture susceptibility of HMA mixtures under freeze–thaw cycles

The objective of this research study was to evaluate moisture susceptibility of hot mix asphalt (HMA) with and without Zycosoil as a nano-organosilane anti-stripping additive and hydrated lime in the form of slurry. Moisture resistance was evaluated on mixtures prepared with two sources of aggregate: limestone and siliceous. The base bitumen used was AC 60–70 grade, and two anti-stripping additives. The functional characterization of the base bitumen with and without Zycosoil was analyzed by means of Fourier Transform Infrared Spectroscopy (FTIR). The performance of HMA mixtures under multiple freeze–thaw cycles was evaluated through the following tests: resilient modulus; indirect tensile strength; tensile strength ratio and fracture energy. The findings of this research indicate that use of both additives enhanced the resilient modulus ratio of the mixtures. It was also observed that the effects of anti-stripping additives on specimens made by siliceous aggregate are more pronounced than those prepared with limestone aggregates. Fracture energy results also proved that use of Zycosoil additive will increase adhesion bond between the aggregates and asphalt binders, and in turn influences the moisture resistance of the mixture to moisture damage.

Evaluation of HMA moisture damage in Wisconsin as it relates to pavement performance

The Wisconsin Department of Transportation (WisDOT) has been using the tensile strength ratio (TSR) test (ASTM D-4867) to predict the potential susceptibility of asphalt mixture to moisture damage and other associated pavement deterioration. The objectives of this paper are to evaluate the relationship between the performance of asphalt pavements in the field and the TSR values measured in laboratory on the original asphalt mixtures used in constructing pavements, and to evaluate the effect of anti-stripping additives on field performance. To assess the moisture damage problem in the field, 21 existing WisDOT pavement sections that were built prior to the adoption of the TSR parameter as a requirement, were selected to cover a wide range of locations and aggregate sources. The TSR and the pavement performance data (pavement distress index or PDI) for these projects were collected from the WisDOT pavement management database. The results indicated no relationship between TSR and field pavement performance as measured by the PDI, and no relationship between TSR and specific pavement distresses that are related to moisture damage (surface raveling and rutting). To evaluate the effect of using anti-stripping additive, a database study and a laboratory study were conducted. The database showed an effect of using anti-stripping additives on the pavement performance and also on the specific pavement distresses that are related to moisture damage. In laboratory testing, anti-stripping additive was not found to change the rheological properties of asphalt binders, nor to improve the rutting and fatigue related properties of asphalt binder as measured by the dynamic shear rheometer (DSR). However, they were found to increase the adhesion of asphalt binder to selected mineral aggregate surfaces, especially when the binder bond is exposed to water. These findings lead to believe that better field performance is achieved by better adhesion between binders and aggregates. The findings also point out that although the TSR testing is sensitive to the use of anti-stripping additives, it does not provide a good simulation of factors playing roles in critical distresses such as rutting and raveling. What could be more effective is a simpler test allowing direct measure of adhesive bond between aggregates and asphalts. Such a test could replace the TSR in making a decision to require or not require the use of anti-stripping additive. The pull-off tensile strength test by the Pneumatic Adhesion Tensile Testing Instrument (PATTI) is also shown to give promising results.

Effect of antistripping additives on environmental damage of bituminous mixtures

The main objective of this study was to investigate the effect of environmental damage (stripping) on the hot mix asphalt (HMA) creep behavior. To achieve this objective, 24 different HMA combinations using different mix parameters were evaluated for their resistance to static creep deformations. The mix parameters include: two types of asphalt cement, three types of aggregate gradation, and two types of antistripping additives (limestone dust and calcium stearate hydroxide). Marshall specimens were prepared at optimum asphalt contents and tested for static creep. Part of the prepared specimens were exposed to freezing–thawing conditioning according to AASHTO T283. The findings of this study indicated that conditioning of HMA specimens has a significant effect on the increase of creep deformation. This is especially true for open graded aggregate gradation mixes. For unconditioned mixes and conditioned mixes, prepared using mid and upper limits of ASTM specification for dense graded aggregate, the creep deformation of mixes prepared using 80/100 asphalt was less than that for mixes prepared using 60/70 asphalt. The opposite trend was noticed for conditioned specimens prepared using open graded aggregate gradation. Antistripping additives showed significant effect on reducing stripping and creep behavior. Mixes which used calcium stearate hydroxide additive showed less stripping and creep deformation than those which contained limestone dust additive.

The effects of damage evaluation techniques on the prediction of environmental damage in asphalt mixtures

The main objective of this study was to investigate the effects of evaluation methods on the prediction of environmental damage (stripping) of hot mix asphalt (HMA). To achieve this objective, four different environmental damage evaluation techniques were used to evaluate asphalt mixtures prepared using different mix parameters. The environmental damage evaluation techniques include either percent reduction in indirect tensile strength or Marshall stability or percent increase in static creep deformation due to environmental damage. In addition, theTexas boiling test which is based on visual evaluation of the percent of coated aggregate was used for environmental damage evaluation. The findings of this study indicated that the estimated environmental damage is significantly affected by the method of evaluation. Retained indirect tensile strength and retained stability were found to be less sensitive to environmental damage. Moreover, the static creep test was the only method used that was able to monitor the effect of used asphalt and aggregate gradation on the environmental damage of HMA, while the effect of antistripping additives on reduction stripping was easily monitored by the Texas boiling and static creep test. Finally, it was found that different environmental damage evaluation techniques revealed different results of using calcium stearate hydroxide.

New Chemical Antistripping Additives for Bituminous Mixtures

Abstract The main objective of this study was to develop new, low cost, chemical antistripping additives that have low negative effects on Hot-Mix Asphalt (HMA) properties such as stability and low temperature cracking potential. To achieve this objective, HMA specimens were prepared using limestone aggregate, asphalt with 80/100 penetration, and different types of chemical antistripping compounds. Eighteen different low cost chemical compounds were prepared and added to the HMA at different percentages. The effect of 28 different combinations of additive types and amounts on the HMA stripping was evaluated using the modified Texas Boiling Test. The results indicated that out of the 28 evaluated combinations of additive type and amount, five combinations caused a negative or no impact on stripping resistance. On the other hand, twelve additive combinations show relatively small improvements in stripping resistance. Another 11 additive combinations showed a positive effect on stripping resistance. Five of these 11 additives showed a high positive improvement in the stripping resistance (increase in coating areas was greater than 20%). However, of these five additives, four caused a high reduction in the asphalt ductility and penetration, while the fifth one (Aluminum mono-stearate) caused a small reduction in ductility and an insignificant change in penetration. This suggests that this additive is suitable for use as an antistripping agent. The effects of antistripping additives in improving stripping resistance may be explained by the formation of strong links between the metal surfactant and with both the aggregate and asphalt. The stripping resistance of metal surfactants derived from the saponification reaction between the metal hydroxide [Ca(OH)2 and Al(OH)3] and the triglyceride of stearic acid was less than those derived from pure stearic acid (by neutralizing the stearic acid with the metal hydroxides). This may be explained by the presence of glycerol in the metal surfactants derived from the saponification reaction. Since glycerol contains three hydroxyl groups, it makes strong hydrogen bonding with water and appreciable interaction with the metal surfactant due to the presence of dipole-dipole forces. Accordingly, some of the metal surfactant and its attached asphalt are leached out during the boiling test producing a lower anti stripping effect.

Relating Adhesion and Cohesion of Asphalts to the Effect of Moisture on Laboratory Performance of Asphalt Mixtures

Antistripping additives and polymer modifications are two common modifiers used to improve the fundamental properties of asphalt binders as those properties relate to the performance of asphalt mixtures. Adhesion and cohesion are two important related properties of asphalt binders that can affect asphalt mixture performance before and after water conditioning. The purpose of this study was to quantify the effects of antistripping additives and polymers on the adhesion and cohesion of binders and to relate these effects to the performance of mixtures as measured in the laboratory before and after water conditioning. The performance tests of asphalt mixtures included indirect tensile strength, uniaxial compression permanent deformation, and Hamburg wheel tracking. Asphalt mixtures were produced with different modified binders and with two aggregate types. The binders were modified with antistripping additives and polymers and by chemical treatment and oxidization methods. Granite and limestone were selected...