Correction: Study of the modification mechanism and high-temperature rheological properties of OMMT/SBS-modified asphalt

The swift expansion of expressways and the substantial increase in traffic flow in China have prompted a demand for elevated standards in road durability, performance, environmental sustainability, and related aspects. Conventional polymer-modified asphalt, including materials like SBS, SBR, and rubber asphalt, has gained widespread adoption due to its commendable attributes such as superior high and low-temperature performance, water resistance, and fatigue resistance [1][2][3][4][5], resulting in notable practical achievements. However, challenges persist, notably the intricate modification procedures and suboptimal compatibility with asphalt binders [3,6], emerging as the primary technical impediment hindering the advancement of polymer-modified asphalt. Nanomaterials find widespread application as modifiers in asphalt due to their diminutive particle size (1 nm to 100 nm), expansive specific surface area, and favorable compatibility with asphalt [7]. Among these nanomaterials, nano-clay, categorized as a layered silicate, encompasses montmorillonite (MMT), vermiculite (VMT), kaolinite clay (KC), and others, characterized by particle sizes ranging from 200 nm to 400 nm [8]. Nano-clay exhibits the potential for intercalation or exfoliation upon blending with an asphalt binder [9]. Recent research indicates that the incorporation of nano-montmorillonite enhances the rutting resistance, fatigue resistance, aging resistance, and storage stability of the asphalt binder [10].Notably, compared to MMT, OMMT demonstrates superior performance by forming an exfoliated structure in the asphalt binder [11]. Furthermore, nano-clay significantly improves the dispersion of polymers within the asphalt binder, resulting in noteworthy economic and technical benefits [12]. The development of nano-modified asphalt pavement materials emerges as a pivotal research direction in the field of road engineering [13]. This avenue holds considerable promise, given its high potential for widespread adoption and its positive outlook for future development.In recent years, both domestic and international researchers have conducted extensive investigations into asphalt modified with nano-clay. The preparation of nano-clay modified asphalt involved a melt blending process, with the dispersion of nano-clay in the asphalt binder analyzed using X-ray diffractometry (XRD). The findings revealed that montmorillonitemodified asphalt exhibited an intercalation structure, while organic montmorillonite-modified asphalt demonstrated an exfoliated structure [14]. The incorporation of an appropriate quantity of organic montmorillonite markedly enhances the compatibility between SBS and the base asphalt. In a study by Shah et al., OMMT was introduced into SBS-modified asphalt, revealing that OMMT facilitates the achievement of improved physical and rheological properties when the clay is dispersed on a nanometer scale within the modified asphalt [15]. Furthermore, Wang et al. identified that the OMMT modifier effectively addresses the deficiency of poor rutting resistance observed in bio-asphalt at elevated temperatures [16]. Jahromi et al. discovered that, beyond enhancing the rheological properties of nano-clay modified asphalt, the inclusion of OMMT also enhances asphalt elastic modulus G and aging resistance [17]. Focusing on storage stability, Yu et al. conducted a static storage test to evaluate the storage stability of both MMT and OMMT-modified asphalt. The study revealed that the storage stability of asphalt modified with MMT or OMMT remains highly stable when the clay content is below 3 wt%. Moreover, the storage stability of OMMT-modified asphalt surpasses that of MMT-modified asphalt, a finding supported by XRD testing. The presence of mostly exfoliated structures in OMMTmodified asphalt during modification suggests superior compatibility and dispersion ability with the base asphalt compared to MMT [14]. In Tan et al.'s investigation, OMMT was introduced into crumb rubber modified asphalt (CRMA), revealing that the modified asphalt with 3 % and 4 % OMMT content exhibited the most favorable storage stability [18]. Ke et al.delved into the performance of styrene-ethylene-butadiene-styrene copolymer (SEBS)/OMMTmodified asphalt, highlighting OMMT's dual impact of enhancing high-temperature performance and promoting increased interaction between SEBS and asphalt molecules. This interaction improved the overall compatibility between SEBS and asphalt, consequently leading to a substantial enhancement in the hot storage stability of SEBS-modified asphalt [19]. In the context of aging resistance, Zhang et al. [20][21][22][23] used AFM, XRD, and FTIR to study the microstructural changes of base asphalt and clay modified asphalt before and after aging. The results showed that FTIR and XRD showed that OMMT/SBS modified asphalt formed an intercalation structure, and the matrix stiffness of the asphalt increased after short-term aging.The AFM morphology gradually transitioned to single-phase with aging. OMMT can effectively prevent single-phase changes, indicating that OMMT/SBS modified asphalt has good UV aging resistance. However, the inclusion of layered clay effectively mitigates this phenomenon, underscoring the superior anti-aging performance of clay-modified asphalt.Furthermore, the introduction of OMMT serves to prevent the rupture of molecular bonds in asphalt by absorbing specific ultraviolet solar energy. This absorption mechanism contributes to enhancing the asphalt's resistance to ultraviolet aging [24]. Liu et al. have substantiated this claim. Through FTIR testing of modified asphalt before and after aging, coupled with an assessment using functional group indices to scrutinize the aging performance at a microscopic level, it was observed that the incorporation of OMMT markedly enhances the ultraviolet aging resistance of Sasobit warm mix asphalt. This finding serves to advance the potential application of Warm Mix Asphalt (WMA) in regions characterized by intense ultraviolet exposure [25]. Lu et al. [26] compared the effects of naphthenic oil and OMMT on the performance of SBS modified asphalt. The results show that both OMMT and naphthenic oil can improve the storage stability of SBS modified asphalt. OMMT deteriorates low-temperature performance, reduces high-temperature viscosity, and the high-temperature sensitivity reflected by softening point and rutting factor increases with the addition of OMMT [27].In summary, existing research on OMMT modified asphalt primarily focuses on investigating its rheological properties, storage stability, and anti-aging performance. These studies collectively validate the positive modification effects of OMMT, providing valuable insights for further exploration. However, there remains a gap in understanding the micromechanism underlying OMMT-modified asphalt, necessitating a more comprehensive qualitative and quantitative analysis of its modification mechanism.Building upon this context, the current study aims to investigate the traditional performance aspects of OMMT-modified asphalt. High-temperature rheological properties were assessed using a DSR, while FTIR was utilized for qualitative analysis of characteristic peaks and functional groups. Furthermore, a correlation between OMMT content and characteristic functional group indices was established to quantitatively determine OMMT content in modified asphalt. Additionally, AFM technology was employed to explore the impact of OMMT nano-modified materials on the micro-surface morphology of asphalt. This investigation aims to elucidate the micro-modification mechanism and identify factors contributing to the performance enhancement of OMMT-modified asphalt.This paper used a SBS modified asphalt as the reference asphalt. The selected SBS modified asphalt is prepared by high-speed shear mixing of SK 90# base asphalt and 5 %SBS modifier at 180 ℃. Its main technical indicators are shown in Table 1. The testing process is mainly based on the " Standard Test Methods of Asphalt and Bituminous Mixtures for Highway Engineering " (JTG E20-2011) [28][29]. With the development of the production process, the particle size of layered clay is more refined in recent years. Some particles have reached a few micrometers or even smaller.However, there is no research to demonstrate how the particle size affects the performance of modified asphalt. For this reason, two kinds of nano-clay (montmorillonite modifier) with different particle sizes were selected for study, in which the content of MMT was more than 95 %. In order to improve the compatibility with asphalt binder, montmorillonite was modified by quaternary ammonium salt intercalation agent to prepare OMMT [30], which was recorded as OMMT-C (≥200 mesh) and OMMT-F (≥325 mesh), in which the specific gravity of OMMT-C and OMMT-F were 1.68 g/cm3 and 1.72 g/cm3, respectively. The of different is shown in Table the of the two kinds of were characterized by and the results are shown in 1. is from the that both materials have a The of OMMT-C and OMMT-F are and there is no in the structure of the kinds of OMMT-C and OMMT-F with different particle sizes were selected as modifiers and SBS modified asphalt was used as reference asphalt to prepare nano-clay modified asphalt in to the current the content of nano-clay in modified asphalt is no more than %. to the of nano-clay modifier content on asphalt performance, this paper different OMMT content (1 3 The used in the is the by of with and The of this is nm for surface morphology analysis and evaluate the high stability of asphalt, is used to the and elastic properties of asphalt binder by the shear modulus and of asphalt. The rutting factor can the of and at the were using a shear including and were with a of and a of with a of was from to with a of with a of The was to with a FTIR FTIR is the most used testing for qualitative and quantitative analysis of organic materials such as asphalt. 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With the introduction of 3 % OMMT the particle The factor contributing to the in modified asphalt in the of nano-clay to due to its expansive specific surface Additionally, the compatibility between nano-clay and asphalt is the as the nano-clay content the dispersion the can the impact of OMMT content on the overall indices of modified asphalt. The of the mechanism underlying different OMMT content was conducted using Furthermore, a analysis was on the overall indices of modified asphalt with OMMT modifiers of particle high stability of different OMMT-modified was characterized by rutting factor and the results are shown in to a in observed at an OMMT content of its low-temperature performance, OMMT-modified asphalt with content of and is to it that the rutting factor of SBS modified asphalt exhibits increase at OMMT an as OMMT content This from the of the structure formed within the modified asphalt at OMMT the OMMT content a stable structure is established in the modified asphalt, the of and asphalt with Additionally, the enhancing impact of OMMT-F on the high-temperature rheological properties of SBS modified asphalt surpasses that of highlighting the of OMMT particle size on these OMMT with a particle size can within SBS modified asphalt, forming a stable introduction of OMMT modifier results in an of the rutting This indicates that OMMT modification enhances the resistance of SBS modified asphalt, consequently its rutting resistance. the rutting factor for modified Asphalt at from the incorporation of OMMT into the modified asphalt, leading the within the asphalt to the OMMT This process increases the to a structure characterized by intercalation and The OMMT a structure within the asphalt, and the This a substantial on significantly enhancing the performance of the modified it is that high OMMT content improves the high-temperature performance of modified asphalt, it have potential effects on performance. the content of OMMT the structure formed by OMMT also the of asphalt at leading to increased stiffness and potential This have a impact on the low-temperature resistance of asphalt, it more to when the OMMT content for modified asphalt, it is to the rheological properties at high and explore the physical and within utilized the FTIR test The FTIR of the modified asphalt, OMMT comprehensive is from the results that, at an OMMT content of both the and of the nano-modified asphalt a In order to the impact of different OMMT on the of the modified asphalt, study conducted on asphalt with OMMT of 3 and 5 %. The analysis to identify the primary characteristic peaks and functional of OMMTmodified asphalt. investigation into the of OMMT on the of characteristic peaks in the modified asphalt. in the between OMMT content and functional group was established to the quantitative and of OMMT-modified shown in the main functional in the of SBS modified asphalt are at and both of which are by the of In also characteristic peaks and functional as shown in Table The OMMT-C and OMMT-F modifiers characteristic peaks and functional groups. this study the FTIR of the OMMT-F modifier to its physical and the of the nano-clay OMMT in the peaks observed at and from the of the The primary of this functional group is to the physical and water within the OMMT In the of modified layered the introduction of modifiers results in the presence of functional by peaks at and These peaks primarily from the of the within the organic modifiers also by water and water between in layered such as and The of is the of in OMMT, and the absorption at is and in OMMT structure, in which and are the main characteristic peaks in OMMT FTIR test of OMMT-modified asphalt is and the results are shown in in the FTIR of OMMT-modified asphalt, upon the addition of OMMT, a to that of SBS modified asphalt. 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OMMT-F modifier is to SBS modified asphalt, the shown in that compared with OMMT-C modified asphalt, the single-phase of OMMT-F modified asphalt is more indicating that OMMT-F modifier has compatibility with modified asphalt. In it can from the that the structure of the matrix surface changes to and in the modified asphalt the is that OMMT dispersed in the asphalt binder as a agent is to the of The surface of OMMT can the morphology of the structure in the asphalt process it can from the morphology that compared with OMMT-C modified asphalt, the structure in OMMT-F modified asphalt is and the size is gradually This due to the of the exfoliation structure, which is to the of OMMT in the modified asphalt and further the single-phase of the improve the overall stiffness of the increase the of the development of the structure, that its the show that the of OMMT modifier on the of asphalt molecular is more and the on the process of structure is also resulting in a in the size of The addition of modifiers increases the modulus of the asphalt surface and improves its of surface of modified the changes in the of different modified asphalt, a and a is the of the on the surface of the and is the of in the test and are used to the of different modified and the results are shown in the the of the in the test can from that the results of the two kinds of show with the addition of OMMT the surface of asphalt and the of surface morphology of modified asphalt This is with the research results of Zhang et The main is that the intercalation or exfoliation structure is formed in the OMMT-modified asphalt, and the has good compatibility with the asphalt. OMMT modifier on the and in the asphalt which the asphalt to a single-phase can used as a which contributes to the of the size of the structure and the dispersion of the structure in the asphalt that the modified asphalt has a more stable is the of the is the of the structure the of and the of the structure is the of the structure as the it can that the of the is than that of the and its with the of the results of the characteristic of OMMT-C modified asphalt are shown in is from the that with the addition of OMMT-C the modified asphalt to single-phase and the of in the morphology and the test is mainly of and The of structure is which is significantly than that of SBS modified asphalt, which is with the results in the The of the of OMMT-C modified asphalt is and its with the of the the of is than that of SBS modified asphalt, the overall of OMMT-C modified asphalt is than that of SBS modified asphalt of the of the of This indicates that its surface modulus is and its is OMMT-F modifier is to SBS modified asphalt, the of the characteristic of modified asphalt is shown in with SBS modified asphalt and OMMT-C modified asphalt, OMMT-F modified asphalt a The of the surface increases in which the of the structure is and the of the is which is significantly than the of the The results show that the of structure on the overall performance of modified asphalt is this investigation, nano-clay OMMT was employed to SBS reference asphalt, resulting in the preparation of OMMT/SBS modified asphalt. The performance of the OMMTmodified asphalt performance and the rutting factor the microscopic mechanism was analyzed using FTIR and AFM The are The introduction of OMMT significantly the physical properties of the modified asphalt. the in and with the increase in the softening indicates that the modification improves the high-temperature stability of the asphalt. This enhancement is primarily to the interaction between the nano-clay particles and the SBS Moreover, the of OMMT on the performance is highly on both the particle size and with particles and a more on the OMMT of and the SBS modifier particles a within the asphalt which the of a stable This is for the overall performance, as it prevent and and resistance to However, when the OMMT content the resulting of SBS particles a in the performance, as this the of the modifier and the rheological The FTIR analysis absorption peaks at and which are characteristic of the OMMT incorporation into the asphalt. These peaks as indicators for the presence of nano-clay in the modified asphalt. Furthermore, the quantity of OMMT is to have a correlation with the functional group at these that FTIR can used as an for the quantitative of OMMT content in asphalt The interaction between OMMT and the in the asphalt matrix is in its overall OMMT primarily with the enhancing the stiffness of the modified asphalt. This interaction the modified asphalt the stiffness of the leading to a more and stable This is for the a single-phase in the modified asphalt, which is for both the and The incorporation of OMMT the morphology of the asphalt by promoting the dispersion of This process increases the overall of the modified asphalt, the of that to and dispersion a in enhancing the rheological properties, including the and improved of the asphalt, it more to and rutting traffic The findings that OMMT-modified asphalt with an can significantly improve the and performance of the However, it is to the OMMT content to the effects of modifier the of and which the modified asphalt's resistance to aging and studies on investigating the aging of OMMTmodified asphalt and to the effects of OMMT content on