•The feasibility of using rice husk ash as an asphalt modifier in hot mix asphalt was investigated.•The addition of RHA to asphalt binder improved the rheological and physical properties of asphalt ...binder.•The use of RHA enhanced the Marshall stability and stiffness modulus of asphalt mixtures.•Asphalt mixtures with RHA showed better rutting resistance and fatigue performance than control mixtures.
Using rice husk ash (RHA), as a waste byproduct of rice milling, in bituminous roadways provides valuable advantages such as reduction of environmental degradation, lowering construction costs and saving natural resources. However, there are limited numbers of studies on application of this material in asphalt mixture. The objective of this study was to investigate the effects of RHA as an asphalt modifier on hot mix asphalt. Bitumen blends with 5%, 10%, 15% and 20% RHA modifier. For evaluation of the rheological properties of asphalt binders, various tests including penetration grade, ductility, softening point, rotational viscosity and dynamic shear rheometer were conducted. Also, the mechanical properties of asphalt mixtures including Marshall stability, stiffness modulus, rutting resistance and fatigue behavior were assessed. The results showed that the rheological properties of bitumen were enhanced by adding RHA. Furthermore, RHA modification had positive impacts on the Marshall stability, stiffness modulus, rutting strength and fatigue performance of asphalt mixtures.
Soil polluted by oil and its derivatives is a critical environmental issue worldwide that jeopardizes ecological systems and causes geotechnical problems. This review paper focuses on the previous ...studies concerning the impacts of oil pollution on soil geotechnical properties. To this end, related academic literature on this topic was investigated and discussed. The findings of this study demonstrated that the addition of oil pollution in coarse-grained soils significantly reduces particle surface roughness. On the other hand, in fine-grained soils, it results in flocculation and secondary aggregation of clay particles, less aggregated and loose packing in the soil matrix, the formation of isometric pores, the formation of fissure-like pores, and an increase in mesoporosity. In general, it was found that the geotechnical properties of oil-polluted soils are mostly determined by the physicochemical and/or physical interactions between the soil and contaminant. Additionally, previous research has demonstrated that oil pollutants alter the geotechnical properties of cohesive and non-cohesive soils significantly, including the Atterberg limits, particle-size distribution, compaction behavior, unconfined compressive strength, friction angle, cohesion, hydraulic conductivity, and consolidation characteristics. However, no general pattern could be established for the majority of them. Besides, it was found that the degree of geotechnical property alteration of oil-polluted soil is strongly influenced by the soil type and features, as well as the quantity, type, and chemical composition of oil pollutants.
•The feasibility of using rice husk ash and date seed ash as alternative filler in hot mix asphalt was investigated.•The use of RHA and DSA enhanced the Marshall stability and stiffness of asphalt ...mixtures.•The usage of RHA and DSA fillers improved the rutting performance of asphalt mixtures.•Asphalt mixtures with RHA and DSA showed better fatigue resistance compared to control mixtures.
Today, waste materials have been increasingly utilized as alternative raw materials in asphalt mixtures in order to decrease construction costs, conserve natural resources and reduce environmental problems. The main purpose of this research is to investigate the potential of using two biomass ashes, which are agricultural waste/byproducts namely rice husk ash (RHA) and date seed ash (DSA), as filler material in hot mix asphalt (HMA) by replacing conventional filler at different percentages. The percentages of DSA and RHA separately used in the mixtures were: 0%, 25%, 50%, 75% and 100%. The effects of DSA and RHA fillers on mechanical properties of asphalt mixtures were assessed using Marshall stability, MQ, indirect tensile stiffness modulus, wheel track and four point bending fatigue tests. Furthermore, the asphalt mastics were produced to evaluate the effect of fillers on mastic viscosity. Based on the results, asphalt mixtures with DSA and RHA fillers showed higher stability and stiffness modulus in comparison with the control mixture. Also, using biomass ashes improved the thermal sensitivity of mixtures and the adhesive force between asphalt and aggregates, which caused an enhancement in rutting resistance and fatigue life of HMA mixtures.
The incorporation of waste glass solids, as alternative raw materials, into highway pavements provides excellent benefits such as conserving natural resources, reducing construction costs, lowering ...environmental pollution, and increasing the accessibility of road aggregates. Since waste glass possesses an all-around fracture, high stiffness, and internal friction angle properties, it may improve the quality of asphalt mixtures. Despite these advantages, asphalt mixtures containing glass aggregates, referred to as glasphalt mixtures, suffer from several disadvantages. The poor adhesion between asphalt and glass aggregates leads to stripping and reduces the glasphalt mixture’s strength under moisture and vehicle load. Therefore, a suitable additive should be used to solve the glasphalt mixture’s moisture sensitivity and improve its mechanical properties. This study investigated the effect of styrene butadiene styrene (SBS) on the mechanical properties and moisture sensitivity of glasphalt mixtures. Five samples with various percentages of SBS copolymer (0%, 2%, 4%, 6%, and 8%) and waste glass particles (10%) were manufactured. The AASHTO T283, Marshall, indirect tensile fatigue, and repeated load axial tests were performed on both modified and unmodified samples. The results demonstrated that the use of SBS, with better adhesion between the binder and glass aggregates, reduced the modified glasphalt mixtures’ moisture sensitivity, extended their fatigue life, and enhanced their resistance to permanent deformation compared to control mixtures.
Bio-oils are increasingly used to enhance petroleum bitumen’s intermediate and low-temperature characteristics regarding their economic and environmental benefits. Research has shown a beneficial ...impact of nanomaterials on altering bitumen’s high-temperature characteristics. The present study uses a mixture of rice bran oil and nano-calcium oxide to improve the performance of bitumen in all three temperature conditions. Rice bran oil was added to pure bitumen at doses of 3, 5, and 7 % relative to the weight of bitumen. The rheological tests (dynamic shear rheometer, multiple stress creep recovery, linear amplitude sweep, and bending beam rheometer) demonstrated that using rice bran oil in bitumen enhanced its performance at intermediate and low-temperatures but declined its performance at high-temperatures. Therefore, to improve the performance at high-temperatures, the bituminous sample containing 5 % rice bran oil was combined with 1, 3, and 5 % nano-calcium oxide, followed by repeating the rheological tests on them. The samples modified with nano-calcium oxide showed increased friction and shear stress, viscosity, and rutting parameters. Besides, the samples exhibited reduced sensitivity to aging compared to the bio-oil samples. However, the non-recoverable creep compliance and percentage of recovery showed improvements. The fatigue life of bio-oil samples decreased after adding nano-calcium oxide. However, the fatigue life remained higher than the base bitumen sample when adding 1 % nano-calcium oxide. Fourier-transform infrared spectroscopy analysis showed that a new chemical reaction occurred due to adding nano-calcium oxide to bitumen containing rice bran oil. Besides, the scanning electron microscope image revealed that the nano-calcium oxide particles are uniformly and homogeneously distributed within the bitumen sample containing 5 % rice bran oil. Consequently, the mix containing 5 % rice bran oil and 3 % nano-calcium oxide increases the resistance against high-temperature failures and improves the low-temperature performance compared to the base bitumen sample.
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•Adding rice bran oil (RBO) to bitumen leads to a decrease in excretion pollution.•The incorporation of nano-CaO and RBO decreases negative environmental effects.•The combination of RBO and nano-CaO improved low-temperature cracking resistance.•Nano-CaO increased the rutting resistance of bio-bitumen.•RBO improved the fatigue life of base bitumen.
Aging due to sunlight and the passage of time is an effective element in the occurrence of moisture damage in hot asphalt mixtures. Still, the effects of this parameter are scarcely considered in the ...experiments examining the moisture damage potential. Accordingly, this study investigated the effect of aging on the performance of hot asphalt mixtures and examined the improvement of moisture damage performance by using antistripping additives via mechanism and functional tests. Two types of aggregates (limestone and granite) with different degrees of moisture sensitivity, two types of bitumen (PG64-16 and PG58-22) with different performances, and two additives (Wetfix liquid additive and nanohydrated lime) as bitumen modifiers were used. Bitumen samples and asphalt mixtures were subjected to short- and long-term aging. The pull-off test was performed to explore the aging effect on different failure mechanisms (cohesion and adhesion), and the indirect tensile stiffness modulus (ITSM) test was conducted to study the asphalt mixture’s performance against moisture damage. The results specify that aging, in terms of hot asphalt mixture hardening in dry and wet conditions, decreased the MSR (resilient modulus wet to resilient modulus dry ratio), and this decline was greater in long-term aging. The pull-off test results exhibited that aging, especially in the long term, decreased the asphalt mixture’s adhesive strength in dry and wet conditions; this decline in adhesion was greater in the wet than in the dry state, and this difference decreased the wet-to-dry adhesion strength ratio (the pull-off ratio). The additives relatively improved the yield modulus of the asphalt mixture, but their effect was greater in the wet state. A comparison of the pull-off test results in cohesion and adhesion failure demonstrated that Wetfix was more effective in improving bitumen–aggregate adhesion, whereas nanohydrated lime was more effective in enhancing bitumen adhesion. The resilient modulus (Mr) ratio in wet-to-dry conditions indicated that nanohydrated lime had better effects on the overall performance of the aged asphalt mixture against moisture damage. To investigate the effect of additives on the performance of asphalt mixtures, a t-test was performed in all modes of control, short-term aging, and long-term aging. The findings showed the effect of Wetfix and nanohydrated lime on increasing the modulus of elasticity of the samples.
This study examines the potential of the soft computing technique, namely, multiple linear regression (MLR), genetic programming (GP), classification and regression trees (CART) and GA-ENN (genetic ...algorithm-emotional neuron network), to predict the ultimate bearing capacity (UBC) of cohesionless soils beneath shallow foundations. For the first time, two grey-box AI models, GP and CART, and one hybrid AI model, GA-ENN, were used in the literature to predict UBC. The inputs of the model are the width of footing (B), depth of footing (D), footing geometry (ratio of length to width, L/B), unit weight of sand (γd or γ′), and internal friction angle (ϕ). The results of the present model were compared with those obtained via two theoretical approaches and one AI approach reported in the literature. The statistical evaluation of results shows that the presently applied paradigm is better than the theoretical approaches and is competing well for the prediction of qu. This study shows that the developed AI models are a robust model for the qu prediction of shallow foundations on cohesionless soil. Sensitivity analysis was also carried out to determine the effect of each input parameter. The findings showed that the width and depth of the foundation and unit weight of soil (γd or γ′) played the most significant roles, while the internal friction angle and L/B showed less importance in predicting qu.
Biomasses are environmentally friendly additives that lower pollution in pavement engineering because of their biodegradability. On the other hand, to build a safe, long-lasting pavement, rutting ...prevention is crucial. This study provides a comprehensive review of the efficacy of biomass as recyclable materials in reducing rutting and enhancing characteristics of asphalt mixtures. According to findings, the hydrocarbon polymer properties of lignin and biomass ash improve asphalt binder consistency, hardness, and function at high temperatures. The results showed that biochar, due to its solid shape, enhances the stiffness and viscosity of the mixtures. The high-temperature performance of asphalt binder is improved by bioshell waste, which increases rutting parameters. Thus, biomass like ash, lignin, and biochar can increase asphalt binder rheology and rutting resistance due to chemical forces such as Van der Waals and hydrogen ions. The macroscopic and microscopic investigation also shows higher interaction and better adhesion in bioasphalt. However, asphalt binders containing bio-oil exhibited no unique behaviors due to their lubricant impact. Based on the estimation of the life cycle assessment (LCA), it was determined that biomass utilization has the potential to decrease the cost and CO2 emissions of pavement engineering by as much as 10% and more than three times, respectively. An examination of recyclability revealed that biomass utilization can decrease the requirement for additional stabilizers by as much as 20%.
•CFMAB has less sensitivity to temperature variations and high resistance to cracking.•CFMAB is not suitable for low-temperature conditions.•The use of CF more than 3%, improves the high service ...temperature of binder by one unit.•Asphalt mixtures manufactured with CFMAB have a superior resistance to rutting and fatigue damages.•The value of 3% CF can be considered the optimum content for binder modification.
Improving the properties of asphalt binders is an effective method to enhance pavement strength. The aim of this study is to evaluate the rheological properties of ceramic fiber modified asphalt binder. To this end, modified asphalt binders with 1, 3, and 5 wt% of ceramic fibers were prepared and binder tests including penetration, softening point and ductility, rotational viscometer, dynamic shear rheometer and bending beam rheometer tests were performed on them. The results of the experiments indicated that although the use of ceramic fibers somewhat reduces the resistance of asphalt binder at low temperatures, not only retains the binder resistance against cracking but also improves its high-temperature performance. These results were confirmed by the wheel track and indirect tensile fatigue tests which were conducted to verify the binder tests. Thus, these fibers can be considered as suitable additives to improve the performance of binder and asphalt mixtures and their optimum content will be 3%.
The construction of suitable roads in rainy areas has created problems in the construction process due to the low resistance of asphalt to moisture. To solve this problem, materials are commonly used ...that make mixtures resistant to moisture; however, these materials may reduce the dynamic resistance of asphalt. Therefore, materials should be used that, in addition to increasing the dynamic resistance, also increase the moisture resistance of asphalt mixtures. One of these materials used in this research is steel wool fiber (SWF), which in addition to creating conductive roads also could have a significant effect on moisture resistance. In this study, the impact of 2%, 4%, 6%, 8%, and 10% SWF on the Marshall stability and moisture sensitivity of mixtures was investigated using the Marshall stability and indirect tensile strength (ITS) tests, respectively. Moreover, using SWF as a conductive fiber, the conductivity properties of asphalt mixtures were explored to find the optimal amount of electrical conductivity. The results of the Marshall stability test indicated that by increasing SWF contents, the stability of mixtures increased, compared with the base sample, and greater amounts of 6% SWF resulted in the reduction of the Marshall stability. The results of ITS showed that modification of bitumen by SWF increased ITS and tensile strength ratio (TSR) amounts of mixtures. 6% SWF was the optimal amount for enhancing the resistance of asphalt mixtures to moisture sensitivity. The results of the electrical resistivity test showed that the resistivity had three phases: high resistivity, transit, and low resistivity. Mixtures containing less than 4% SWF illustrated an insulating behavior, with electrical resistivity greater than 7.62 × 108 Ω.m. At the transit phase, the resistivity of mixtures had a sharp reduction from 7.62 × 108 Ω.m to 6.17 × 104 Ω.m. Finally, 8% SWF was known as the optimal content for the electrical conductivity of mixtures.
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