Asphalt Filler Research Articles

Rheological and mechanical properties of bauxite residue as hot mix asphalt filler

Bauxite residue (red mud) is a highly alkaline solid waste generated in the process of production of aluminium metal from bauxite ore. More than 5.5 million tons of red mud is generated in India. The aluminium industries, worldwide and in India, have expressed strong need for dedicated research to explore large-scale utilization of red mud. Towards this end, the objective of this study is to investigate the use of red mud as a filler in hot mix asphalt (HMA). Stone dust, a traditionally used filler material, is used as the control filler. For a comprehensive evaluation approach, the present investigation is conducted at three levels: filler, mastic and mixture characterisation. Red mud and stone dust fillers are characterised using scanning electron microscopy (SEM), pH, Rigden voids, methylene blue value, particle size analysis, and specific surface measurement. Mastic rheology is studied using the dynamic shear rheometer by temperature sweep and multiple stress creep and recovery (MSCR) tests. Finally, dense-graded bituminous concrete (BC) mixes are designed by the Marshall method followed in India, at different filler contents of both filler types. Mixture performance is investigated in terms of indirect tensile strength and Cantabro abrasion loss. Results show that addition of both fillers improved the viscoelastic response of the base binder. Red mud mixes showed higher resistance to disintegration and higher tensile strength than the control mixes with stone dust filler. Based on the findings of this study, red mud showed good potential for use as a filler in dense graded bituminous mixes.

Examination of the utilization of aluminum dross in road construction

Aluminum dross is a recyclable by-product of the aluminum manufacturing process. Since the use of aluminum alloys increased in large quantities, which cause a significant amount of aluminum dross produced, therefore, the need for alternative solutions are also increased. The goal of this study is to investigate the utilization possibility of dross as an alternative asphalt filler. During the research aluminum dross and limestone (as reference material), which is well-known filler in asphalt technology, were investigated. Different tests were done on the samples: specific gravity, particle size distribution, BET specific surface area and Rigden voids were determined on the fillers. Scanning electron microscope was used to characterize the morphological features of fillers. To reveal the affinity of fillers to bitumen hydrophilic/hydrophobic properties and oil adsorption ability were also investigated. These examinations help to better to understand the interaction between fillers and binder material. With the use of fillers asphalt mixtures and specimens were also prepared for stiffness tests and asphalt cracking temperature tests. The results show a good correlation between dross and limestone fillers, therefore aluminum dross may be an alternative to partly substitute limestone filler.

The use of high content of fine crumb rubber in asphalt mixes using dry process

The two traditional methods to incorporate crumb rubber into asphalt mixes are the dry process and wet process. Although dry process has greater advantages including more crumb rubber usage, conservation of natural resources, and so on, there is less desire to apply dry process compared to wet process because of its poor performance. This study aims to evaluate the usage of high contents of crumb rubber powder (CRP) as filler in asphalt mixes and provide further development in the dry process method by considering the curing process effect, different CRP contents and micro-scale size of CRP filler. The conventional filler of mixes was replaced with 20, 40 and 60% CRP by weight of filler and the mechanical properties of modified mixes, including moisture susceptibility, stiffness modulus, rutting performance and fatigue life were evaluated. The results indicated that simultaneously applying curing process and very fine CRP in the asphalt mix, enhanced considerably the resistance of asphalt mixes against failures. In addition, the performance of mixes with high contents of CRP was weakened, which could be improved by curing process.

Evaluation of fatigue damage and healing of asphalt mastics for different filler contents

Fatigue damage and healing are two very important characteristics for designing asphalt concrete (AC). Fatigue damage degrades material properties, whereas healing recovers the material properties at rest periods after damage. Mastic is a blend of asphalt binder and fine aggregates (fillers) and is a component of AC composite. Fatigue damage and healing mostly occur in the asphalt binder and mastic. This study evaluates the effect of the fines and binder grade of mastic on the fatigue damage and healing of mastic. A total of six mastics (with different binder grade and asphalt–filler ratio) are tested to determine fatigue damage and healing. It is found that fatigue resistance increases up to the addition of 20% fines in the mastic. Addition of fines more than 20% decreases the fatigue resistance. A physicochemical model is used to predict healing in mastic. Healing decreases with the addition of fines in the binder and higher binder grade.

Investigation of Aluminum Dross as a Potential Asphalt Filler

There is a great concern about utilizing different waste materials all over the world. Stockpiling in landfills is not a final solution, therefore researchers try to find alternative methods to utilize these materials [1-5]. One potential area may be road construction. Fillers are one of the most important components of asphalt pavements. It has a dual role. First of all, these fine grained mineral materials (d<0.063 mm) enhance the cohesion with bitumen. Second is to fill the gaps between the particles to produce more compact mixture [6]. The aim of this research is to reveal the possibility of utilization of aluminum dross as a potential asphalt filler. This material, which is a by-product of aluminum casting process, is produced in large quantities year by year and its storage in landfills is not a proper solution. Therefore, there is an increasing demand to utilize this material. During the research material structural tests were made, which can characterize the samples (limestone powder, dross), and the cohesion between bitumen and filler can also reveal. Particle size distribution, BET specific surface area and porosity were investigated. Scanning electron micrographs were taken and oil adsorption test were also made.

Alkali-activated materials obtained from asphalt fillers and fluorescent lamps wastes

Alkali-activated materials, which some authors often call geopolymers, can be described as inorganic solids that form three-dimensional networks with molecular structure similar to organic polymers, and are able to combine qualities similar to cements with those of traditional ceramics and zeolites.The polymerisation reaction takes place between solid aluminosilicate powders and alkaline solutions at low temperature and therefore this process is classified as eco-efficient. In addition, this process allows the recycling of a large variety of amorphous aluminosilicate waste materials, which makes it very attractive from the environmental point of view.In this work, alkaline activated materials have been prepared using exclusively industrial and urban wastes to replace both, the aluminosilicate powder (from asphalt fillers and fluorescent lamps wastes) and the alkaline activator (from aluminium manufacturing industry). The materials obtained have been fully characterised. A mineralogical and microstructural study of these materials was conducted by FTIR, XRD, and ESEM-EDX. Moreover, it has been determined their bulk density, strength resistance, water absorption and leaching tests, confirming their suitability for being used as urban pavement.

Engineering properties and microwave heating induced ice-melting performance of asphalt mixture with activated carbon powder filler

In order to solve deicing issues of asphalt pavement through a eco-friendly and effective way, activated carbon powder (ACP) was utilized to partially replace the fillers in asphalt concrete to improve deicing ability of pavement by microwave heating. In this research, scanning electron microscopy (SEM) was used to observe the microscopic morphology of ACP and mineral powder (MP), and their infiltration interface with asphalt. The engineering properties including rutting resistance, cracking resistance and moisture susceptibility of asphalt mixture were then investigated to evaluate the effect of ACP substitutions on the performance of asphalt mixture. Fillers, asphalt mastic, and asphalt mixture with different ACP substitutions were heated under microwave radiation and their microwave heating characteristics were studied using infrared thermal imager. The ice-melting characteristics of asphalt mixture with different ACP substitutions were described by infrared thermography and ice-melting speed. The results show that due to the porous structure and material properties of ACP, the infiltration effect between ACP and asphalt is better than that of MP and asphalt. With an increase of ACP substitution, the optimal asphalt content and moisture susceptibility of asphalt mixture increased slightly. The rutting resistance and low temperature crack resistance were improved significantly, while the moisture damage resistance was slightly sacrificed. Besides, the ACP could greatly improve the microwave heating efficiency of asphalt mastic and mixture. As the amount of ACP substitution increased, the microwave radiation energy utilization and ice-melting efficiency of asphalt mixture were improved via microwave heating.

Investigating Effects of Coal Flotation Waste on Aged Hot Mix Asphalt Performance

The present study was an attempt to investigate the effect of fresh and old coal flotation waste (coal waste), used as asphalt filler and additive, on the properties of hot asphalt mixtures in aged and un-aged condition. In this experimental study, fresh and old coal flotation waste, obtained from the Central Alborz Coal Washing Plant, were used to produce filler specimens (100% Wt.) as substitutes for limestone powder and asphalt additive (7% w.t). Finally, the performance of the asphalt mixture containing flotation waste was evaluated using Marshall Stability and indirect tensile tests. The afore-mentioned compounds were used to produce specimens under short-term aging conditions and the results were compared with other results obtained under un-aged condition. The results indicate that flotation waste improved performance of hot mix asphalt under short-term aging conditions.

Quantitative comparison of evaluation indices for asphalt–filler interaction ability within filler critical volume fraction

Asphalt–filler interaction plays a key role in the performances of asphalt mastic and asphalt mixture. However, the current studies ignore the filler critical volume fraction that has significant effects on asphalt–filler interaction ability. There is also lacking quantitative comparison of evaluation indices within filler critical volume fraction. In this study, two kinds of virgin asphalt binders and three kinds of mineral fillers were selected to fabricate asphalt mastics, and the dynamic shear rheological properties of virgin asphalt binders and asphalt mastics were measured, and the interaction evaluation indices complex viscosity coefficient Δη*, intrinsic viscosity [η], complex modulus coefficient ΔG*, K-B-G*, Einstein coefficient KE, L-A-δ and K-B-δ were quantitatively compared. The results indicate that complex viscosity coefficient Δη* and intrinsic viscosity [η] are not suitable for evaluation of asphalt–filler interaction ability. ΔG* and K-B-G* can evaluate the differences of asphalt and different fillers interaction ability based on the same kind of asphalt binder. Nevertheless, ΔG* and K-B-G* cannot differentiate the effects of asphalt binder on asphalt–filler interaction ability well. Although Einstein coefficient KE can evaluate asphalt–filler interaction ability, the Einstein coefficient KE is fitting results, and cannot distinguish the interaction ability under different filler volume fractions. L-A-δ and K-B-δ can differentiate the interaction ability of different asphalt binders and fillers well, and also the sensitivity factors of index K-B-δ are greater than L-A-δ. Therefore, K-B-δ is the most suitable for evaluating asphalt and filler interaction ability. Based on the evaluation index K-B-δ, asphalt–filler interaction ability increases initially and decreases afterwards with an increase in filler concentration within filler critical volume fraction.

Influence of diatomite filler on rheological properties of porous asphalt mastic

ABSTRACTMineral filler is usually added into asphalt mixture to stiffen the asphalt binder and improve mixture strength. This is particularly important for open gradations such as porous asphalt which is known to have poor strength and durability because of its open nature and large air voids. The interactions that occur between asphalt binder and filler results in certain mastic properties that affect the mixture strength. In this study, the effect of different types of filler on the rheological properties of asphalt–filler mastics for porous asphalt were evaluated using the frequency sweep and multiple stress creep recovery (MSCR) tests. Hydrated lime, cement and diatomite with 2% content were selected to produce asphalt–filler mastic. The influence of diatomite filler was investigated and compared to the hydrated lime and cement fillers. Results indicated that the use of filler increased the stiffness of mastics. The MSCR test showed that hydrated lime and diatomite mastics exhibited the lowest non-recoverable compliance and high recovery than the original PG 76 binder and cement mastic. Diatomite mastic exhibits the best resistance to rutting at high temperatures and stress levels, verifying that the use of diatomite filler is favourable because of its high temperature properties.

Moisture-induced damage resistance of asphalt mixture entirely composed of gneiss and steel slag

Gneiss and fine steel slag are seldom used in the construction of asphalt pavement due to their poor performances. Asphalt mixture entirely composed of gneiss (coarse aggregate) and steel slag (fine aggregate and asphalt filler) was proposed in this research in order to promote their wide use. Limestone fine aggregate and filler were functioned as control groups. The inadequacy of using 100% of gneiss to prepare asphalt mixture and the performance deterioration mechanism of fine steel slag were discussed based on some newly revealed material characteristics and previous research results, and corresponding improvement measures were established first. Then four asphalt mixtures (two fine aggregate and two filler) were designed by Superpave procedure. Finally, the moisture stabilities of uncompacted aggregate-mastic system and compacted asphalt mixture were fully investigated, and hot water damage mode and freeze-thaw damage mode were adopted. Results suggested that asphalt mixture entirely composed of coarse gneiss and re-processed fine steel slag possessed satisfactory moisture resistance performance.

Laboratory investigation on high- and low-temperature performances of asphalt mastics modified by waste oil shale ash

The objective of this study was to use two kinds of waste oil shale ash (OSA) as partial replacements of conventional mineral filler for evaluating high- and low-temperature performances of asphalt mastics. First, asphalt mastics with conventional mineral filler replacement by OSA (OSA/MF) of 0, 10, 15, 30% by volume based on filler–asphalt (F/A) ratios of 0.8, 1.1, 1.4 were prepared. Then, based on the measured penetration, softening point and ductility of modified asphalt mastics, the overall desirability analysis was adopted to determine the optimal OSA/MF. Subsequently, the high-temperature and low-temperature properties of asphalt mastics with the optimal OSA/MF were studied through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. Results indicated that OSA could improve the high-temperature stability but reduces the temperature susceptibility of asphalt mastics, whereas the asphalt consistency is influenced insignificantly. Besides, the high- and low-temperature properties of asphalt mastics could be improved by the addition of OSA and the oil shale semi-coke (OSSC) modified asphalt mastic is slightly better than oil shale fly ash (OSFA) modified asphalt mastic in some aspects. Based on these results, the optimum F/A ratios could be obtained to enhance the high-temperature and low-temperature properties of asphalt mastics.

INVESTIGATION INTO POTENTIAL OF FLY ASH OBTAINED FROM COAL-BASED POWER PLANTS TO CONTRIBUTE TO SUSTAINABLE ENVIRONMENT

The main objective of this study was to investigate the potential of using fly ash as a mineral fillerin asphalt mixtures to reduce the amount of fly ash generated from coal-based power plants in Bangladeshrequiring disposal. To achieve this, several mix designs which included fly ash were developed and comparedwith mixtures using cement as a mineral filler, with mixtures of cement and fly ash with different ratiosconsidered and their performances evaluated. It was found that the design with a bitumen content and fly ash as amineral filler was within the economical range and, when its Marshall stability and flow values were comparedwith those of cement, it was found to be satisfactory. Also, the moisture susceptibility of an asphalt mixture withfly ash was checked through immersion-compression tests and compared with that of one with cement as amineral filler. As it was observed that fly ash generated from coal-fired power plants can reduce the damagecaused to asphalt by moisture and is more cost-effective than conventional fillers, it is proposed that using it as afiller material in pavements could reduce the substantial damage suffered by the environment.

Experimental evaluation of rice husk ash and fly ash as alternative fillers in hot-mix asphalt

Ever-growing concern to protect the environment concentrated the attention of the society on the possible re-use of different agricultural and industrial wastes in road construction. This research study depicts the effect of using wastes like rice husk ash (RHA) and fly ash (FA) as a replacement of conventionally used hydrated lime (HL) as fillers in hot-mix asphalt (HMA). Primarily, the dense graded bituminous macadam (DBM) mix specimens were made in the laboratory with varying proportions ranging from 2% to 8% of HL, RHA and FA by following design mixes according to the Marshall method and compared the results with control mix as prepared by utilising 2% HL. The performances of the said mixes were studied through the Marshall quotient, indirect tensile strength and tensile strength ratio. Results of investigation show better performance of HMA with the addition of RHA and FA and also proved to be economical as the optimum bitumen content is reduced by 7.5% from that of control mix when added at 4% filler ratio. Further, RHA shows a greater affinity to the bitumen attributing the highest stiffening effect of the bituminous mastic droplets compared to that of other used fillers with good compatibility at the micro level by satisfying the essential criterion.

High‐ and Low‐Temperature Properties and Thermal Stability of Silica Fume/SBS Composite‐Modified Asphalt Mortar

Recently, China has started paying more attention to environmental protection, and the efficient utilization of exhaust gases produced by smelting has emerged as a key problem concern. The silica fume collected from the exhaust gases produced by smelting ferrosilicon or industrial silicon was often used as a cement concrete admixture. Using silica fume as an asphalt modifier can make exhaust gases profitable. In this study, silica fume/SBS composite‐modified asphalt mortar was prepared to improve the performance of asphalt. The effects of the silica fume content, temperature, and ratio of filler asphalt on the composite‐modified asphalt mortar were studied through the cone penetration, softening point, viscosity, dynamic shear rheological (DSR) test, and bending beam rheometer (BBR) test. The thermal stability of composite‐modified asphalt was analyzed through the thermal analysis test. The results showed that with the increase of silica fume content and ratio of filler asphalt, the high‐temperature performance of asphalt mortar was improved; the content of silica fume had a great influence on the low‐temperature performance of asphalt mortar, the optimum silica fume content was 7%; increasing the ratio of filler asphalt reduced the low‐temperature cracking resistance of asphalt mortar; the incorporation of silica fume enhanced the initial decomposition temperature, thermal residual rate, temperature in which the weight loss rate reaches the maximum, and the endothermic peak of maximum temperature and improved the properties of asphalt.

Improving the mechanical properties of rubber floor tiles by rock powder particle as filler in natural rubber

This research studies the influence of rock powder particles which are used as filler in natural rubber in order to improve the mechanical properties of rubber floor tiles. Moreover, it studies about eliminating the waste from the filler asphalt manufacturing process (rock powder).The filler characterization of rock powder particle was found that it composed of 84% of calcium oxide. The SEM images showed morphology of rock powder particles had spherical shape and irregular shape. The rubber floor tiles had black color because of the black rock powder particles. The rubber floor tiles mixing rock powder particle were tested the mechanical properties. It was found that the overall of mechanical properties was similar to standard formula (non rock powder). Therefore, it was concluded that the waste from asphalt manufacturing process can be used to benefit the rubber floor tile for the manufacturing industry. Especially, It can also reduce the problem of pollution from asphalt manufacturing process.

Investigating influence of mineral filler at asphalt mixture and mastic scales

This study is devoted to understand the mechanisms of mineral fillers in asphalt at the mixture and mastic scales. To do so, the physical 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 information 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 inclusion 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.

Utilization of aluminium dross as asphalt filler

Utilization of aluminium dross as asphalt filler

Influence of mineral filler on the low-temperature cohesive strength of asphalt mortar

The effects and influence mechanisms of different filler-to-bitumen ratios on the low-temperature cohesive strength of asphalt mortar were studied using quantitative testing technology. Two control variables, namely filler-to-bitumen ratio (the quality of the mineral filler/quality of asphalt) and temperature, were selected for this experiment. The first variable was divided into six groups. The cohesive strength of each group was then measured under different low-temperature conditions. Results show that the optimization of filler-to-bitumen ratio was related to the cohesive strength of the asphalt matrix, which was in turn associated with the change on the surface between the asphalt matrix and the strength of the mineral power fillers generated from asphalt embrittlement. Therefore, the optimal filler-to-bitumen ratio should be determined by the local low-temperature conditions. Moreover, the cohesive strength of the asphalt matrix, its embrittlement state and the contact surface strength effect of asphalt filler should be comprehensively considered in determining the optimal filler-to-bitumen ratio.

Laboratory investigation on the properties of asphalt concrete mixture with Rice Husk Ash as filler

Incorporating of waste and/or by-product materials in construction industry such as production of hot asphalt concrete mixtures provide valuable advantages in terms of environmental and economic points of view. Accordingly, in this laboratory study, it was investigated to use Rice Husk Ash (RHA) instead of conventional mineral filler in hot asphalt mixtures.The mechanical properties were assessed by conducting Marshall Stability and Indirect Tensile Strength tests. While moisture damage and long term aging were inspected by determining Index of Retained Strength (IRS) and Mean Marshall Stability Ratio (MMSR), respectively.The experimental results have shown a significant improvement in the mechanical properties and a substantial upgrading in durability of the produced mixtures i.e. asphalt concrete mixtures with RHA as a mineral filler (RHAAC) in comparison with the control mixtures which were prepared with OPC as a mineral filler (OPCAC).As a result of this study, RHA can be incorporated instead of conventional mineral filler in asphalt concrete mixtures particularly in areas where there is extensive RHA waste.