Investigating inﬂuence of mineral ﬁller at asphalt mixture and mastic scales
|نوع نگارش مقاله||
scopus – master journals – JCR
۴٫۲۷۶ در سال ۲۰۲۰
۲۶ در سال ۲۰۲۱
۰٫۹۰۱ در سال ۲۰۲۰
|شاخص Quartile (چارک)||
Q1 در سال ۲۰۲۰
خرید محصول توسط کلیه کارت های شتاب امکان پذیر است و بلافاصله پس از خرید، لینک دانلود محصول در اختیار شما قرار خواهد گرفت و هر گونه فروش در سایت های دیگر قابل پیگیری خواهد بود.
فهرست مطالب مقاله:
This study is devoted to understand the mechanisms of mineral ﬁllers in asphalt at the mixture and mastic scales. To do so, the phys- ical properties of asphalt mixtures and mastics were evaluated; in addition, a chemical investigation was presented into the mastic scale for the sake of providing insight into the possible mechanisms between asphalt binder and mineral ﬁller. Three mineral ﬁllers namely hydrated lime (HL), limestone (LS), and cement bypass dust (CD) were incorporated into an asphalt binder at diﬀerent ﬁller- to-binder (F/B) ratios. For the mechanistic evaluation of the mixtures, the indirect tensile strength (ITS), moisture damage evaluation, resilient modulus, and static creep-recovery tests were carried out. The fracture energies also were quantiﬁed for all the studied mixtures. The results of penetration and softening point tests, as well as their pertinent penetration index (PI), were discussed to elucidate some physical properties of the mastics. The nuclear magnetic resonance (NMR) spectroscopy was performed on the mastics to obtain infor- mation on molecular structures of the formed composites. The ﬁndings of this study emphasize that the physical properties of mixtures and mastics are highly dependent on type and concentration of mineral ﬁller. The 1H NMR and 13C NMR results proved that the inclu- sion of the studied ﬁllers did not change the molecular structure of the base asphalt binder; hereby the physical mechanisms stand behind the attained properties. It is believed that the ﬁndings of this work would contribute to growing knowledge of the mechanisms of mineral ﬁllers in asphalt mixtures.
|بخشی از متن مقاله:|
Flexible asphalt pavement layers consist of mineral ﬁl- ler, coarse, and ﬁne aggregates all cemented by the asphalt binder and blended at pre-speciﬁed weight proportions determined from the mix design method. The blend of min- eral ﬁller and asphalt binder forms the asphalt mastic des- tined to play a major role in controlling the mechanical behavior of its mixture . The coarse and ﬁne particles act as the structural skeleton of the constructed pavement. Practically, the hot mix asphalt (HMA) mixture can be considered a system consisting of the mastic coating the aggregates rather than the aggregates coated with asphalt binder . Consequently, the incorporation of the mineral ﬁller is indispensable and can signiﬁcantly alter the proper- ties of the mixture. ASTM D 242 speciﬁcation  requires that the ﬁller passes through No. 16 (1.18-mm), No. 30 (600-lm), No. 50 (300-lm), and No. 200 (75-lm) sieves with the requirements of 100%, 97–۱۰۰%, ۹۵–۱۰۰%, and 70–۱۰۰% passing, respectively. In general, the mineral ﬁller is used in the HMA mixture for diﬀerent purposes [4–۶]:
To meet the gradation requirements of the whole minerals;
To reduce the optimum content of the asphalt binder by ﬁlling the voids in the granular skeleton;
To stabilize the mixture;
To increase the post-compaction resistance of the
To improve the bond strength within the asphalt-
To stiﬀen the asphalt; and
To increase the asphalt volume in the mixture.
The properties of the asphalt mixtures are aﬀected by several factors such as the physical and chemical properties of the forming components and the mechanisms between components . It can be speculated that the quality of the mineral ﬁller is an important factor that controls the lifetime of roads to some extent. Several types of mineral ﬁllers substantially diﬀer in both physical and chemical properties have been practically used in HMA: natural ﬁl- lers such as mineral dust obtained from the screening and crushing of aggregates, and imported ﬁllers, e.g. lime, Port- land cement, ﬂy ash, and slag . A lot of research about the role of mineral ﬁllers in the asphalt mixtures has been carried out in terms of diﬀerent physical properties such as the indirect tensile strength, toughness index, rutting , Marshall stability, retained strength , stiﬀness , fracture energy density, dissipated creep strain energy to failure , fatigue cracking , and moisture damage . At the mastic scale, several authors (e.g. [10,14,15]) have reported that the potential for physical reinforcement of mineral ﬁllers in their mastics may depend on the type, size, concentration or grading of the ﬁller. Also in the liter- ature there is no certainty of correlation between the mea- sured properties of mastics or reinforcement and the properties of the used ﬁller. Usually, the Rigden voids value of the mineral ﬁller is used as an indicator of the rein- forcement . Therefore, the physical evaluation is not probably suﬃcient to understand the mechanisms of min- eral ﬁller in the mixture. However, the response of the HMA mixture is material-type dependent and can vary due to the presence of additional mechanisms between the asphalt and the mineralogy of mineral ﬁllers . Although there have been many publications to determine the characteristics of asphalt mixtures containing mineral ﬁllers, the behavior of ﬁllers in the mixtures is still a contro- versial topic among researchers worldwide, particularly when it comes to the criteria of selecting a ﬁller over another, due to the lack of both physical and chemical studies to fully understand the ﬁller mechanisms in an interactive manner . In previous studies [18–۲۰], the interfacial interaction between mineral ﬁllers and asphalt binder was investigated with the aid of physical and chem- ical tests, including dynamic mechanics analysis, diﬀeren- tial scanning calorimetry, surface free energy testing, Fourier transform infrared spectroscopy, and atomic force microscopy. A signiﬁcant impact of physicochemical inter-actions was registered, which are inﬂuenced by the speciﬁc surface area of the mineral ﬁllers. However, the uncon- trolled variations of the properties of asphalt binders and mineral ﬁllers prompt for additional investigations into the inﬂuence of mineral ﬁllers at the mixture and mastic scales. In this regard, the current investigation is intended to understand the role of introducing mineral ﬁllers of varying amounts and types from the perspective of pre- pared mixtures and mastics. The asphalt mixtures were evaluated in terms of indirect tensile strength (ITS), resili- ent modulus, static creep-recovery, and moisture damage. The mastics were tested for penetration and softening point for the sake of physical evaluation, also the nuclear mag- netic resonance (NMR) spectroscopy was used to explore the possible chemical mechanisms in the formed mastics.
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