Study Investigating the Influence of Warm-Mix Asphalt Additives on Rutting and Fatigue Performance of Nano-Modified Asphalt Binders

The current study investigates the synergized effect of a nanomaterial and two warm mix additives asphalt (WMA) additives on different properties of asphalt binders. The study used an optimal percentage of 2% for nano-Al2O3; two WMA additives were used in different concentrations. The results revealed that the addition of WMA additives increased the softening point of nano-Al2O3 modified asphalt binder. Penetration and ductility results showed a decrease after the introduction of WMA additives. The viscosity of nano-Al2O3 modified asphalt binders showed a reduction after the introduction of WMA additives. Rutting evaluation was done by using the superpave rutting parameter and multiple stress creep and recovery (MSCR) test. The fatigue performance of the asphalt binders was measured using the superpave fatigue parameter and linear amplitude sweep (LAS) test. Results showed that the introduction of WMA additives improved the rutting and fatigue performance of nano-Al2O3 modified asphalt binders. The introduction of WMA additives enhanced the aging performance of the nano-Al2O3 modified asphalt binders.

Influence of Different Warm Mix Additives on Characteristics of Warm Mix Asphalt

The interest in minimising fuel consumption and greenhouse gas emissions among road specialists is increasing. Thus, methods for reducing asphalt concrete mixing and compaction temperatures by a few tens of degrees Celsius without compromising the long-term performance has become a topic of significant interest. This study is focused on the analysis of warm mix asphalt (WMA) prepared with locally available materials in order to determine the suitable technology applicable to the specific traffic and climatic conditions of Romania. WMA was prepared using different warm mix additives (organic additives, chemical additive, and synthetic zeolite) at different mixing and compaction temperatures, and bitumen blends with these additives were analysed by carrying out the dynamic shear rheometer test and evaluating the penetration index. In conclusion it was noted that most additives did not lead to a significant change of bitumen`s characteristics, but the organic additive had a big influence on the bitumen`s properties. The characteristics of WMA are very similar to those of HMA. The mixing and compaction temperatures could be reduced by approximately 40 °C when WMA was blended with the additives without compromising the performance of the asphalt mixture, compared to hot mix asphalt.

Effects of anti-striping agents on performance of binder and stone matrix asphalt (SMA) mixtures containing polyphosphoric acid/styrene-butadiene rubber composite polymer blends and warm mixture additives

This work evaluated the effect of Anti-Stripping Agents (ASAs) on performance behavior of bitumen and high and intermediate temperature performance of SMA mixtures modified by Poly Phosphoric Acid (PPA), Warm Mix Asphalt (WMA) and Styrene-Butadiene Rubber (SBR) additive. Through this paper, the AC-60/70 and AC-85/100 penetration grade bitumens were used as base bitumen. Moreover, three liquid ASAs (ASA (1), ASA (2), ASA (3)), PPA (1% by weight of bitumen), SBR (2% by weight of binder), and two types of warm mix additives (3% Sasobit and 0.3% Zycotherm) were used as a mixture modifier. For evaluating the performance behavior of bitumen, the rotational viscosity, Dynamic Shear Rheometer, and Bending Beam Rheometer, Multiple Stress Creep Recovery (MSCR), and linear Amplitude Sweep (LAS) tests were implemented. Moreover, Resilient Modulus (Mr), Indirect Tensile Strength (ITS), dynamic creep, wheel track, and Four-Point Beam Fatigue (FPB) tests were performed to investigate the performance of mixture samples. Based on the outcomes of the MSCR test, the utilization of SBR/PPA additive and ASAs decreased the Jnr value. Among modified binders, the binders modified by ASA (2) have the lowest Jnr value followed by binders modified by ASA (1) and ASA (3). According to the outcomes of LAS test, the utilization of ASAs leads to increase in the fatigue life of the original binder. According to the outcomes, the utilization of WMA additives and ASAs caused the Mr, ITS, rutting resistance, and fatigue life to increase. Among ASAs, the ASA (2) has the greatest influence on enhancing the performance of mixtures. Based on results, Sasobit additive has a better effect than Zycotherm on enhancing the properties of samples.

Influence of the Skid Resistance of Ultrathin Wearing Course with Various Types of Asphalt Binders

Ultrathin wearing course (UTWC) has been widely applied in both asphalt pavements preventive maintenance and functional overlay. This study’s objective is to evaluate the influence of different modified asphalt binders with warm mix additives on the skid resistance of UTWC and to reveal the attenuation law of skid resistance of UTWC. Three types of modified asphalt binders (Styrene-Butadiene-Styrene- (SBS-) modified asphalt, Acrylester Rubber- (AR-) modified asphalt, and SinoTPS-modified asphalt) and sasobit warm mix asphalt additive were selected to prepare asphalt mixtures. The Model Mobile Load Simulator 3 (MMLS3) was used to simulate repeated vehicle loading and abrasion. The British Pendulum Number (BPN) and Mean Texture Depth (MTD) were chosen to evaluate the skid resistance of the UTWC. The Analysis of Range (ANOR) and Analysis of Variance (ANOVA) were used to verify the significance of asphalt binder on the antiskid performance of the UTWC. ANOR and ANOVA show that the influence of different modified asphalt binders on the skid resistance of the UTWC is significant. The SinoTPS modified asphalt mixture can maintain high texture roughness before and after abrasion, providing excellent and durable skid resistance. The influence of the addition of a warm mixing additive on the skid resistance of UTWC is not significant, and changes in microtexture mainly reflect its impact on antiskid performance. The decay curve of three modified asphalt binders of the skid resistance of the UTWC can be well fitted into an exponential function. The conclusion will play an essential role in selecting the asphalt binder in a UTWC to improve the antiskid performance.