Types Of Warm Mix Asphalt Additives Research Articles

Effect of warm mix additives and hydrated lime on viscosity and bonding–debonding behaviour of RET and PPA modified asphalt binder with aggregates

Higher energy requirement for asphaltic layer construction with asphalt binder containing reactive elastomeric terpolymer (RET) and poly phosphoric acid (PPA) can be addressed to a greater extent with the addition of warm mix asphalt (WMA) additives. However, moisture damage related problem is one of the concerns with such addition, which further aggravates with an increase in ageing level. The addition of lime may help in addressing moisture damage related problems in such cases. Previous research works show that based on the interaction between asphalt binder and particular WMA additive, the viscosity may undesirably increase also. So far, the influence of different WMA additives (wax, chemical surfactant (CS) and water-based (WB)) on the workability related properties of asphalt binder containing RET and PPA is not understood. It is also not clear if such warm mix additives with/without lime can help in improving long-term bonding with different aggregate types or not. Therefore, this research work aimed at identifying the appropriate WMA additive (with/without lime) which can help in (a) addressing the workability related problem and (b) improving long-term bonding with different aggregate types. To achieve this, different types of WMA additives (with/without lime) were added to RET and PPA modified binder. Viscosity-based measurement and chemical analysis using Fourier transform infrared spectroscopy were performed to understand workability and underlying chemical changes. Results indicated that although wax and CS-based warm mix additives can help in reducing energy demand, the addition of WB warm mix additive will have a negative impact from the workability perspective. Likewise, dynamic contact angle for different binder combinations was measured to evaluate the surface free energy components, which further helped to examine the long-term bonding with different aggregate types. Among different WMA additive types, the use of wax-based WMA additive was found to be most effective in improving compatibility with different aggregate types. Also, irrespective of the binder combination, the addition of lime improved the long-term bonding with considered aggregate types.

Influence of water on warm-modified asphalt: Views from adhesion, morphology and chemical characteristics

It has been proven that warm mix asphalt (WMA) has great potential for reducing the fuel consumption and polluting emissions during the construction of asphalt pavement. However, the moisture susceptibility of WMA is one of the main concerns associated with this material, and it limits the wide application of this technology. In this study, a styrene–butadienestyrene (SBS) modified asphalt was selected as a control binder, and two types of WMA additives with different dosages were used to prepare warm modified asphalt binders. Atomic force microscopy (AFM), dynamic shear rheometer (DSR), and fourier transform infrared spectroscopy (FTIR) tests were carried out to evaluate the influence of water immersion on the nano-adhesion properties, morphological characteristics, stiffness, and chemical constituents of asphalt with and without the WMA additives. The results showed that several changes in the asphalt resulted from water immersion, including a decline in the adhesion performance, the appearance of small bumps on the surface of the asphalt, an increase in asphalt stiffness, and the amount of oxygen-containing functional groups and polar components in the asphalt. In addition, the SBS modifier in the asphalt remained stable during water immersion. Considering the effects of the WMA additives, it was found in this study that the water-induced adhesion degradation, oxidative aging, and increase of the polar components in asphalt could be delayed with the use of Sasobit.

Multi-scale study on the high percentage warm-mix recycled asphalt binder based on chemical experiments

With the development of the transportation industry, the requirements for the warm mix asphalt (WMA) involving high percentage of reclaimed asphalt pavement (RAP) are becoming increasingly high due to its benefit in energy cost and environment. This paper focuses on the chemical properties and multi-scale research of the high percentage warm-mix recycled asphalt (WMRA) binder. Three contents of RAP binder, 30%, 50% and 70%, and two types of warm-mix asphalt additives i.e., polyethylene wax (R) and surfactant (M) were considered. The Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) tests were carried out on the recycled asphalt binders in this paper. The results showed that there was no reverse reaction of aging in the recycling process, and no patterns of change were found between the content of RAP binder and the carbonyl index/sulfoxide index. The increase in the large molecular size (LMS) distribution of the three types of WMRA binders after short-term aging was generally higher than that after long-term aging. After aging, the change in the LMS of the RAP-R binder was relatively large, and the anti-aging performance was weaker than that of the RAP-M binder. The RAP-R binder improved the low-temperature performance of the binder and showed middle-temperature stability, but its anti-aging properties were worse than that of RAP-M binder. There were clear correlations between the glass-transition temperature and the stiffness modulus, between the complex shear modulus and the weight average molecular weight, and between the rotational viscosity and the LMS. However, the correlation between the aging index and the BBR stiffness modulus was not applicable to the recycled binder. This study lays a foundation for evaluating the performance of WMRA binder at the microscopic level and exploring the mechanisms of warm-mix recycling.

Effect of short-term ageing on high-temperature performance of SBS modified binder containing warm mix asphalt additives

Warm Mix Asphalt (WMA) additives have been utilised to reduce working temperatures of Styrene-Butadiene-Styrene modified (SBS) binder to make sustainable pavement with enhanced pavement performance and lower energy consumption. Such modification may change the physicochemical structure of SBS binder and can influence rheological properties. The present study aimed at investigating the effect of short-term ageing on SBS binder containing various types of WMA additives. The experimental design included SBS binder, three WMA additives (Fischer Tropsch wax based- FT, chemical surfactant based- CS and water-based- WB) in three different dosages. The SBS binder was modified with mentioned WMA additives using a high shear mixer. In such way, 10 asphalt binders (one SBS binder and nine WMA modified SBS binders) were prepared. The short-term ageing of asphalt binders was performed using thin film oven. The high-temperature performance of unaged and short-term aged binders was evaluated using Superpave rutting parameter, high temperature performance grade (PG), multiple stress creep and recovery test (MSCR), and frequency sweep test. Based on the results, the short-term ageing showed an adverse effect on high-temperature performance of SBS binder, indicating degradation of SBS binder. Also, WMA additive type and dosages showed a significant effect on SBS binder in unaged and short-term aged condition. Considering the combined effect of WMA additive and short-term ageing, FT and WB additives reduced ageing susceptibility as well as improved rutting resistance of SBS binder. On the other hand, CS modification was able to lower ageing susceptibility, however, degraded high-temperature performance of SBS binder. Based on optimal high-temperature performance and lower ageing susceptibility, SBS binder can be modified with an effective dosage of 1% FT, 6% WB and 1% CS additive (by weight of asphalt binder).

Effects of WMA additives and hydrated lime on high-stress and high-temperature performance of Elvaloy®- and PPA-modified asphalt binder

Addition of Poly Phosphoric Acid (PPA) and polymer modifiers such as Elvaloy® found to improve the rheological performance of asphalt binders. However, such modification has also shown an increase in mixing and compaction temperature. Use of Warm Mix Asphalt (WMA) additives has shown a reduction in construction temperature, hence making such modification environmentally sustainable. Therefore, a control binder (an AC-30 asphalt binder modified with PPA and Elvaloy®) was modified using three different types of WMA additives: Sasobit®, Evotherm® and Advera®. In addition, considering moisture susceptibility of WMA-modified control binders additives, hydrated lime was further added to asphalt binder combinations. The current study involves the performance evaluation of different asphalt binder combinations using (a) Superpave rutting parameter, (b) time–temperature superposition data of complex modulus over a wide range of frequency and (c) multiple stress creep recovery test with application of different stress levels (0.1, 3.2, 6.4, 12.8 and 25.6 kPa). The addition of Sasobit® observed to enhance stiffness, rut resistant and recovery characteristics, whereas, Advera® and Evotherm® addition led to degrade the stiffness, rut resistant and recovery characteristics of a control binder. HL addition to control binder and control binder containing Advera® were observed to have an undesirable effect on rutting resistive performance. However, HL addition to control binder containing Evotherm® and Sasobit® showed improvement in rutting resistivity potential. Overall, high stress levels observed to have a significant effect on all asphalt binder combinations; hence, consideration of higher stresses can play a vital role in binder selection process.

Effects of Sasobit and Deurex additives on asphalt binders at midrange and high temperatures

ABSTRACTThe Warm mix asphalt (WMA) industry has attracted considerable attention due to the additives’ability to reduce the mixing and compaction temperatures of the asphalt mixture. Deurex has showed its potential of being a new additive in this industry. However, properties of Deurex-modified binders have not been studied in details. The objective of this study was to investigate the rheological properties of binders containing various types of WMA additives through conventional test, viscosity, failure temperature, frequency and amplitude sweep. The study included three binder sources (two 60/80 pen asphalt, and styrene–butadiene–styrene (SBS)-modified asphalt), two types of WMA additives (Deurex and Sasobit) and control binders. The results indicated that both Sasobit and Deurex had similar effect on viscosity reduction regardless of asphalt types. The results also indicates that binders containing Deurex had better high-temperature rutting resistance, concerning increased softening point, fail temperature, stiffness and storage modulus. In addition, temperature sweep, frequency sweep and amplitude test show that the Sasobit-modified asphalt binders exhibit a slightly higher storage modulus and complex modulus but a lower phase angle than the Deurex-modified asphalt.

Using Atomic Force Microscopy to Evaluate the Nanostructure and Nanomechanics of Warm Mix Asphalt

AbstractIn this paper, various Atomic Force Microscopy (AFM) techniques are utilized to study the effects of different warm mix asphalt (WMA) additives on the nanostructure and microstructure as well as the adhesive and cohesive properties of an asphalt binder. To achieve this objective, a control asphalt binder was modified with three different types of WMA additives, which included: Advera (a synthetic zeolite), Evotherm, and Sasobit (a commercial wax). The AFM tapping-mode imaging technique was used to examine the nanostructure and microstructure of the different asphalt material considered. In addition, AFM force spectroscopy experiments were conducted using chemically functionalized AFM tips to measure the nanoscale level adhesive and cohesive forces for the control and WMA asphalt binders before and after moisture conditioning. The results of the AFM imaging showed that while the Sasobit additive has reduced the width of the so-called “bee-like” structures within the asphalt binder, the other WMA ad...

Warm Mix Asphalt Technology: A Review

Warm Mix Asphalt (WMA) represents the technologies that allow the reducing of asphalt binders’ mixing and compaction temperatures by reducing its binders’ viscosity. This paper gives a comprehensive chronological review from prior researches and practical experienced among researchers and industrial practitioners while implementing WMA technology including constituent materials, mix design and mechanical performance issues. Within this, the problems and benefits as well as different types of WMA additives were clearly identified as essential for a better understanding of the application of WMA technology in pavement constructions.

Evaluation of natural zeolite as warm mix asphalt additive and its comparison with other warm mix additives

In last decade, warm mix asphalt (WMA) has been used as alternative to hot mix asphalt (HMA) that reduces the temperature of asphalt during production and placement, minimizes greenhouse gases while maintaining the advantages of HMA. This study targets the investigation of natural zeolite as a WMA additive and its comparison with different types of WMA additives (organic, chemical and synthetic zeolite). The bitumen samples have been produced by mixing a 50/70 penetration grade bitumen with different types of WMA additives at various contents. The fundamental and rheological properties of bitumen samples involving different types of WMA additives have been determined by using conventional bitumen test methods and dynamic shear rheometer (DSR).

The role of a surfactant based additive on the production of recycled warm mix asphalts – Less is more

This study assesses the possibility of reducing the costs of warm mix asphalt (WMA) technology, by applying very small quantities of a surfactant based additive (in comparison to other types of WMA additives) to asphalt mixtures with high percentage of reclaimed materials. Using “less” additive, with “less” energy consumption, gas emissions and natural resources depletion, on the production of recycled mixtures with adequate performance, can be a “more” sustainable solution. Performance tests carried out on asphalt mixtures with 50% RAP, in comparison to a conventional mixture, showed a positive effect of the additive on the performance of the mixtures.

Estimating Moisture Sensitivity of Warm Mix Asphalt Modified with Zycosoil as an Antistrip Agent Using Surface Free Energy Method

AbstractWith increasing interest in the use of warm mix asphalt (WMA) in the paving industry, more studies in this field for improvement of WMA properties seem to be necessary. In past decade, several studies focusing on use of Sasobit and asphamin as warm additives in asphalt mixtures have been conducted; however, the effects of these additives on moisture susceptibility of asphalt mixture are still not fully understood. In this study, the moisture susceptibility of WMA evaluated with and without a new nanotechnology material as antistrip additive (namely Zycosoil) by determining the micromechanisms that affect the adhesion bond between the aggregate and asphalt binder and the cohesion strength of the asphalt binder using the surface free energy (SFE) concept and laboratory testing analysis. Indeed, the primary goal of this research was to decrease the moisture damage in WMA. Two types of aggregates, limestone and granite, and two types of WMA additives, namely Sasobit and aspha-min, in addition to as Zy...