Laboratory Investigation of Using Calcium Lignosulfonate as an Oxidation Inhibitor in Bitumen

Abstract

Asphalt mixtures are the major constituent of road constructions. Those mixtures expose to high-temperature levels during the construction process and their life cycle. The bitumen aging occurred because of the harmful effects of elevated temperatures upon the asphalt mixtures, which leads to oxidation, evaporation, and physical hardening within the bitumen structure. The aging phenomenon can intensify the hardness and brittleness of bitumen, which negatively affects the performance of asphalt mixtures. Researchers have investigated different types of bitumen additives to diminish the negative effects of bitumen aging, among which biomass additives are more attractive for researchers because that additives are organic and mainly emanate from waste materials. The current study investigated the effect of calcium lignosulfonate (CLS) at four quantities (i.e., 5%, 10%, 15%, and 20% by the weight of base bitumen) as an antiaging bitumen additive on physical, workability, thermal susceptibility, rheological, and chemical properties of 60/70 penetration grade bitumen. The results revealed that although the addition of CLS into the bitumen enhanced the rigidity of bitumen against rutting failure at high-temperature conditions, the CLS-modified bitumen was more susceptible to fatigue failure than the virgin bitumen at low-temperature regions. The workability analysis showed that the CLS powder could improve the bitumen’s consistency against permanent deformation at high-temperature levels. Although the bitumen’s viscosity increased because of CLS modification, the CLS-modified bitumen provided acceptable workability based on the Superpave specifications. Outcomes from the rheological test revealed that the addition of CLS into the bitumen improved the rutting resistance of bituminous mixtures at high-temperature levels. The SARA analysis indicated that the hardening of CLS-modified samples emanated from the formation of asphaltenes within the bitumen because of CLS incorporation. Different types of aging indices, including PRP, SPI, VAI, and AIRF, which were calculated in this research, showed that the presence of CLS within the bitumen could retard the bitumen’s aging process.

Optimization of CLS Content of Asphalt Mixtures Based on Balanced Mix Design Approach

“…In the study of Fatemi et al on specimens containing diferent amounts of CLS, there was a clear increase in the hardness of bitumen modifed with CLS, leading to the increased hardness of the mixture. Using a similar approach, Zare et al also reported an increase in ITS with an increase in CLS content [15,[19][20][21][22][23][24].…”

“…A study by McCready and Williams confrmed that CLS increases rutting resistance at high temperatures, but reported slightly decreased performance at low temperatures [18]. In the studies conducted by Fatemi et al on the modifcation of bitumen with 5, 10, 15, and 20% CLS, all of these concentrations of CLS exhibited antiaging properties, and the 15% concentration ofered the greatest rutting resistance [15,19,20]. In a series of studies by Zarei et al on various properties of CLS, including cracking resistance and moisture susceptibility under diferent numbers of freezethaw cycles in the presence of reinforcement materials such as fbers, the results showed that CLS can improve fracture toughness under multiple loading modes at various temperatures.…”