Rheology of modified binders under varying doses of WMA additive–Sasobit

Use of warm mix asphalt (WMA) technology to reduce construction temperatures of asphalt mix has gained strong interest worldwide. However, the technology is still in its inception stage in India. Present study evaluated the rheological properties of polymer- and crumb rubber-modified bitumen with various doses of WMA additive Sasobit (1%, 2%, and 3% by binder weight). Frequency sweep and temperature sweep results showed that increase in Sasobit content improved elastic properties of binders. Creep, repeated creep recovery, and multiple stress creep recovery results showed better resistance toward permanent deformation for Sasobit-modified binders in comparison to control binders.     

The rheological behavior of bitumen and moisture susceptibility modified with SBS and nanoclay

The effect of styrene–butadiene–styrene (SBS) and nanoclay additive on performance of pure bitumen and stone matrix asphalt (SMA) mixture was investigated. Different samples with various percentages of nanoclay (2%, 3%, 4%, and 5%) and SBS (0% and 5%) by weight of bitumen were prepared, and the rheological and chemical behavior of bitumen (rotational viscosity, dynamic shear rheometer, SEM, and FTIR), the indirect tensile strength and moisture susceptibility of different mixtures were evaluated. Based on the results, using nanoclay and SBS polymer can improve the rheological behavior of base binder and the resistance of SMA mixtures against moisture damage.     

Moisture susceptibility of warm mixed-reclaimed asphalt pavement containing Sasobit and Zycotherm additives

In this research, the influence of Sasobit and Zycotherm on the properties of reclaimed asphalt pavement (RAP)-warm mix asphalt (WMA) was investigated. Moisture susceptibility was evaluated applying the resilient modulus ratio, the indirect tensile strength ratio, and the fracture energy ratio. Laboratory testing results indicated that Zycotherm mixtures had more resistance to moisture damage than Sasobit WMA and hot mix asphalt (HMA) mixtures. The stiffness of mixtures increased dramatically by increasing the amount of RAP and using Sasobit exacerbated this problem.     

吸湿性聚丙烯纤维的研究

用双螺杆挤出机对共混的等规聚丙烯（IPP）和聚乙二醇（PEG）进行熔融造粒,制得PP改性母料,将其按一定比例与纺丝级聚丙烯切粒混合,在小型纺丝机上进行熔融纺丝制成吸湿性聚丙烯纤维,再经溶液处理后对其进行性能测试。结果表明,当PP改性母料用量为9％时,制得的吸湿性聚丙烯纤维具有很好的力学性能、吸湿性能及抗静电性能。     

Use of Fourier transform infrared spectroscopy to study ageing characteristics of asphalt binders

The present study aims at studying ageing characteristics of conventional bitumen, polymer modified bitumen (PMB) and warm mix asphalt (WMA) by using FTIR. Results of obtained FTIR spectrum were quantified by calculating different indices and finally based on these indices ageing index of the binders for short- and long-term ageing were calculated. Results showed ageing increased amount of complex and high molecular weight components of the binders. PMB was found to have greater ageing resistance than conventional asphalt binders. In case of WMA, results found to be inconclusive, requiring further investigation.     

Investigating the influence of using nano-composites on storage stability of modified bitumen and moisture damage of HMA

In this study, a composite of styrene butadiene rubber (SBR) and nano-clay was made with different ratios and used for bitumen modification. The results show that using nano-composites improves storage stability at high temperature. However, pure SBR modified bitumen is proved not to be stable at high temperature. Investigating the results of indirect tensile strength and indirect tensile strength ratio also indicates that nano-composites improve moisture sensitivity of hot mix asphalt (HMA). Further, according to the results, increasing the content of nano-clay enhances the resistant of asphalt mixtures against moisture damage.     

Rheological properties of bitumen emulsion modified with NBR latex

NBR, a copolymer of butadiene and acrylonitrile, is used for applications requiring resistance to petroleum oils and gasoline. So using NBR as a modifier in bitumen, resistance against the destruction of gasoline and diesel oil will be increased. In this work, rheological properties of bitumen emulsion modified with NBR latex have been investigated. Bitumen emulsion samples were provided with various percent of NBR latex, and the residues of normal and modified bitumen emulsion were tested using ordinary and dynamic shear rheometer (DSR) methods. Using NBR latex as a modifier caused an increase in the softening point of bitumen emulsion residue as well as a decrease in the penetration grade and temperature sensitivity. At the end, by analyzing temperature sweep curves of DSR, it was found that modified bitumen emulsion residues with more than 6% NBR in residue have higher rutting potential temperatures.     

Viscoelastic fatigue resistance of asphalt binders modified with crumb rubber and styrene butadiene polymer

In the present research study, the fatigue behavior of modified asphalt with crumb rubber (CR) and styrene-butadiene-styrene (SBS) are investigated. Each of these additives was mixed with a 85–100 neat bitumen at two different dosages. The time sweep test was used to investigate the viscoelastic fatigue properties of asphalt binders in terms of energy dissipation. Linear amplitude sweep tests were conducted to study the fatigue life of asphalt binders under varying loads based on the concepts of viscoelastic continuum damage mechanics. Results showed that adding CR and SBS can enhance the fatigue resistance of modified asphalts based on the energy approach and viscoelastic continuum damage analysis.     

特殊条件下PE-Y改性沥青混合料的高温性能试验研究

在沥青混合料中掺加PE-Y抗车辙剂的根本目的就在于提高混合料的高温稳定性,增强沥青混合料在高温下抵抗永久变形的能力。为模拟更加恶劣的环境条件,进行了特殊温度车辙试验和浸水车辙试验研究,并首次引入综合稳定指数C作为评价指标。试验结果表明：PE-Y变形体的加筋嵌挤、胶黏作用对提高混合料的高温稳定性效果十分显著,即便在很高的温度条件下,PE-Y变形体交织搭桥形成的空间网络结构仍然能够发挥作用;而且能够降低沥青混合料的水敏感性,使得混合料在荷载、高温和水耦合作用的严酷条件下,仍然能够具有较强的抵抗永久变形的能力。