Optimum Bitumen Content Research Articles

Effects of Crumb Rubber Size and Concentration on Performance of Porous Asphalt Mixtures

The purpose of this study is to investigate the effect of size distribution and concentration of crumb rubber on the performance characteristics of porous asphalt mixture. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps. Firstly, the mixture design was performed to determine the optimum bitumen content. In the latter step, the mixtures were modified by dry process using crumb rubber in three different grain size distributions of #4~#20, #20~#200, and #4~#200 and rubber content of 10%, 15%, and 20% as weight of optimum bitumen. The permeability, Cantabro abrasion loss, indirect tensile strength, moisture susceptibility, and resilient modulus tests were carried out on the specimens. Test results show that #20~#200 sized rubber particles reduced air voids and coefficient of permeability, while they increased the Cantabro abrasion loss. In general, increasing the crumb rubber size and content decreased the performance characteristics of the porous asphalt mixtures.

Pengaruh Penambahan Plastik High Density Polyetilene (HDPE) dalam Campuran Hot Rolled Sheet Wearing Course (HRS-WC) terhadap Parameter Marshall, Kuat Tekan dan Kuat Tarik Belah

In this study, plastics High-Density Polyethylene (HDPE) were used as an additional ingredient of asphalt for HRS-WC mixtures by using a variation of the plastic content of 0%, 2%, 4%, 6% to the asphalt weight. Bitumen content obtained from the optimum bitumen content of 7.5%. The purpose of this research is to examine and to compare the Marshall characteristics, compressive strength and split tensile of HRS-WC mixture. The results showed that the addition of HDPE plastic provide a significant influence on the marshall characteristic, split tensile strength and compressive strength. Asphalt stability with the addition of HDPE by 2%, 4% and 6% compliant with the specifications of marshall stability results respectively amounted to 2589.40 kg, 2257.13 kg and 2385.16 kg.

Investigation of usability of steel fibers in asphalt concrete mixtures

In this study, the usability of steel fibers in order to bear the stresses occurring at the surface layer of pavement, which are directly subjected to the traffic effects, was investigated. In this context, specimens were produced and tested under Marshall Stability Test, and the optimum bitumen content value for the aggregates sample to be used was determined. Results showed that based on the determined value for the optimum bitumen content (5.5%), three specimens for each of a series of different fiber rates (0%, 0.25%, 0.50%, 0.75%, 1.0%, 1.5%, 2.0%, 2.5%) were prepared and the optimum value for fiber rate that results in the best stability value was determined as 0.75%.As a result, steel fiber additions can be used in binder course of flexible pavement because of its positive stability impact.

Evaluation of the mechanical properties of natural asphalt-modified hot mixture

Abstract The objective of this study is to evaluate the usage of natural asphalt in hot mix asphalt by means of determining the Marshall stability, stiffness modulus, indirect tensile strength, and dynamic creep tests. Natural asphalt, which consists of 17% asphalt fraction and 83% mineral fraction, was obtained from Syrian. The optimum bitumen content was determined to be 1% lower for natural asphalt-modified mixtures compared to control mixtures. The stiffness modulus values of the natural asphalt-modified mixtures were higher than those of the control mixtures. The moisture susceptibility of natural asphalt-modified mixtures and control mixtures were evaluated during different freeze–thaw cycles. The natural asphalt-modified mixtures were not as susceptible as control mixtures to moisture damage. Adding natural asphalt to mixtures remarkably decreased susceptibility to permanent deformation. The results presented here demonstrate the positive effects of using natural asphalt.

Determination of the Optimal Polypropylene Fiber Addition to the Dense Bituminous Mixtures by the Aid of Mechanical and Optical Means

Polypropylene fibers are completely native modifiers and they do not have any dependence on abroad in case of technology. When viewed from this point, the modification of bituminous binders with polypropylene fibers is a very important step for our country’s “economical” concerns. In this study, first of all, the physical and chemical effects of polypropylene fibers on bitumen were investigated. Next, the amount of “optimum” polypropylene fibers that has to be added into the mixture was determined. In order to determine it, first, static creep tests and Marshall tests were carried out and then, images of the polypropylene fiber added bituminous binders under fluorescence microscopy were researched. With the application of physical and mechanical tests to the Marshall specimens prepared with the optimum polypropylene amount that was obtained, optimum bitumen content was determined and finally economical analyses were carried out. By carrying out extensive analyses it was seen that the utilisation of polypropylene fibers improves the physical and mechanical properties of the resultant asphalt mixture mainly by enhancing the permanent deformation resistance. On the other hand, polypropylene modification results in 30% economy from bitumen which is a clear indication of the benefit in the mass production of asphalt concrete.

Evaluation of andesite waste as mineral filler in asphaltic concrete mixture

In the study, the use of andesite collected during the shaping process of andesite blocks in asphalt mixtures as mineral filler was investigated. Samples with limestone aggregate were prepared and the optimum bitumen content was then determined by the Marshall Stability Test procedure.Using optimum bitumen content and the same limestone aggregate and aggregate gradation as the andesite waste mineral filler (under No. 200 sieve), the mixtures were prepared and their stability values determined.When comparing all mixtures, the andesite mineral filler with 6% bitumen content showed the highest stability, but this stability value was less than the limestone mixtures with 4% bitumen content.In addition, 6% in the andesite and limestone filler content in the samples, the optimum percentage of bitumen was investigated. Following this, it was found that 5% bitumen content provided the best stability value.As a result, especially in areas where there is widespread andesite waste, if transportation costs do not exceed the cost of limestone, andesite waste can be used instead of limestone in asphalt concrete mixtures as mineral filler.

Study the Use of Cement and Plastic bottle Waste as Ingredient Added to the Asphaltic Concrete Wearing Course

This paper is concerned with the possibility of using plastic bottle waste as an ingredient to the Asphaltic Concrete Wearing Course (AC-WC). This research is explores the effect of adding plastic and cement as ingredient to the mixture of asphalt concrete on the characteristics of Marshall. Plastics that are added are 2:4 and are 6% in weight. It was observed that the optimum bitumen content on the addition of 4% plastic and Marshall stability increases by 19% compared to the AC-WC without addition of plastic. The positive effect of plastic bottle on the characteristics of Marshall, along with its enviromental advantages, make this material a feasible additive.

Prediction of rutting potential of dense bituminous mixtures with polypropylene fibers via repeated creep testing by using neuro-fuzzy approach

This study investigates the potential use of the neuro-fuzzy (NF) approach to model the rutting prediction by the aid of repeated creep testing results for polypropylene modified asphalt mixtures. Marshall specimens, fabricated with M-03 type polypropylene fibers at optimum bitumen content have been tested in order to predict their rutting potential under different load values and loading patterns at 50°C. Throughout the testing phase, it has been clearly shown that the addition of polypropylene fibers results in improved Marshall stabilities and decrease in the flow values, providing an eminent increase of the service life of samples under repeated creep testing. The performance of the accuracy of proposed neuro-fuzzy model is observed to be quite satisfactory. In addition, to obtain the main effects plot, a wide range of detailed two and three dimensional parametric studies have been performed.

Study of Effects of Waste PVC on the Properties of Bituminous Mixes

Waste PVC that has been used previously as mineral water bottles, pipes, electrical fittings etc. are biologically non-degradable and posed an ominous environmental problem which led to severe environmental impact. But molten PVC has a binding property which can be reused with bitumen to reduce the cost of bituminous mix. At the same time the recycling of waste PVC save disposal sites and to reduce the amount of inert drawn from quarries, which often lead to environmental problems. This paper describes the investigation of the properties of bitumen mixed with PVC (2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5% and 20% by the weight of bitumen) at optimum bitumen content and to check the design criteria of bituminous mixes using this bitumen-PVC binder. The investigation concentrated on the test of strength properties of coarse aggregates and Marshall Design properties of bituminous mixes according to the test procedure specified by AASHTO. Some of the measured properties of bituminous mix with bitumen-PVC binder used in this study were within the acceptable recommended limits. On the basis of experimental results of this investigation, it is concluded that the dense graded bituminous mixes with bitumen containing PVC up to 10% can be used for bituminous pavement construction in warmer region from the stand point of stability, stiffness and voids characteristics.

Effect of waste polymer modifier on the properties of bituminous concrete mixes

In the present study, the effect of waste polymer (nitrile rubber and polyethylene in 1:4 ratio) modifier (WPM) on various mechanical properties such as Marshall stability, flow, Marshall quotient (stability to flow ratio), resilient modulus and permanent deformation potential of bituminous concrete overlays has been evaluated. The Marshall tests of the waste polymer modified bituminous concrete (WPMB) mixes, prepared through dry process, indicated the optimum waste polymer modifier content to be 8% (by weight of optimum bitumen content). The waste polymer modified bituminous mix containing 8% WPM showed considerable improvement in various mechanical properties of the mix compared to the conventional bituminous concrete mix.

Effect of Fine Aggregate Physical Properties on the Engineering Properties of Conventional and Polymer-Modified Bituminous Mixtures

Most studies on hot-mix asphalt have used crushed fine aggregate and gravel; research regarding the use of mining sand or marine sand as fine aggregate is limited. This work investigates the effects of fine aggregate physical properties on the engineering properties of hot-mix asphalt. Four types of sand (quarry, river, mining, and marine sand) with two conventional binders (PEN 50/60 and PEN 80/100) and four types of polymer-modified bitumen (PMB) (PM1_82, PM1_76, PM2_82, and PM2_76) were used. Electron microscopy scanning was performed along with sieve analysis and tests for specific gravity and angularity of the fine aggregate on the different types of sand to determine their properties and thereby examine the effects of these properties when the sands were incorporated into a bituminous mixture. Marshall test results showed that fine aggregate physical properties influenced the optimum bitumen contents and engineering properties. The study also revealed that angular and rougher particles of fine aggregate produced lower voids in mineral aggregate, lower optimum bitumen content, higher shear strength, and higher density, which consequently increased the stability of the resulting mixtures. Moreover, a polymer-modified bituminous mixture enhanced stability and stiffness, reduced density, and slightly increased the voids in mineral aggregate.

INVESTIGATION OF USING WASTE ROOFING SHINGLE IN HMA

In this study, waste shingle scraps were used in Hot Mix Asphalt (HMA) samples, stability and flow resistance of HMA samples were investigated. Initially, optimum bitumen content of wearing course was determined by Marshall stability test method and then waste shingle scraps, 1%, 2%, 3%, and 5% in terms of total aggregate weight, were added to HMA samples at the predefined optimum binder content. Besides, control samples were performed and compared with the waste shingle added samples. Test results show that waste shingles can be used in HMA as an additive in accordance with Turkey General Directorate of Highways (TCK) specification limits.

Prediction of Marshall test results for polypropylene modified dense bituminous mixtures using neural networks

This study presents an application of neural networks (NN) for the prediction of Marshall test results for polypropylene (PP) modified asphalt mixtures. PP fibers are used to modify the bituminous binder in order to improve the physical and mechanical properties of the resulting asphaltic mixture. Marshall stability and flow tests were carried out on specimens fabricated with different type of PP fibers and also waste PP at optimum bitumen content. It has been shown that the addition of polypropylene fibers results in the improved Marshall stabilities and Marshall Quotient values, which is a kind of pseudo stiffness. The proposed NN model uses the physical properties of standard Marshall specimens such as PP type, PP percentage, bitumen percentage, specimen height, unit weight, voids in mineral aggregate, voids filled with asphalt and air voids in order to predict the Marshall stability, flow and Marshall Quotient values obtained at the end of mechanical tests. The explicit formulation of stability, flow and Marshall Quotient based on the proposed NN model is also obtained and presented for further use by researchers. Moreover parametric analyses have been carried out. The results of parametric analyses were used to evaluate mechanical properties of the Marshall specimens in a quite well manner.

Repeated Creep Behavior of Polypropylene Fiber-Reinforced Bituminous Mixtures

In recent years, research has been devoted to the control of permanent deformations in flexible pavements. In order to prevent rutting, fatigue, and low-temperature cracking, different types of polymer modifiers have been utilized. The use of polypropylene (PP) fibers as a modifier in pavement mix that can be found locally and at low cost compared to other modifiers is an attractive option. This paper reports on the Marshall design and the optimum bitumen content for asphalt concrete with the addition of polypropylene fibers. Different types of PP fibers were used in order to determine the optimum bitumen content and the optimal PP fiber dosage. Marshall specimens were tested using the universal testing machine to determine the creep behavior of dense bituminous mixtures under repeated loading. The results from the analysis of the tested specimens show that the addition of polypropylene fibers improves the behavior of the specimens by increasing the life of samples under repeated creep testing.

Accumulated strain prediction of polypropylene modified marshall specimens in repeated creep test using artificial neural networks

This study presents an application of artificial neural networks (ANN) for the prediction of repeated creep test results for polypropylene (PP) modified asphalt mixtures. Polypropylene fibers are used to modify the bituminous binder in order to improve the physical and mechanical properties of the resulting asphaltic mixture. Marshall specimens, fabricated with M-03 type polypropylene fibers at optimum bitumen content were tested using universal testing machine (UTM-5P) in order to determine their rheological/creep behavior under repeated loading. Different load values and loading patterns have been applied to the previously prepared specimens at a predetermined temperature. It has been shown that the addition of polypropylene fibers results in improved Marshall stabilities and decrease in the flow values, providing the increase of the service life of samples under repeated creep testing. The proposed ANN model uses the physical properties of standard Marshall specimens such as polypropylene type, specimen height, unit weight, voids in mineral aggregate, voids filled with asphalt, air voids and repeated creep test properties such as rest period and pulse counts in order to predict the accumulated strain values obtained at the end of mechanical tests. Moreover parametric analyses have been carried out. The results of parametric analyses were used to evaluate the accumulated strain of the Marshall specimens subjected to repeated load creep tests in a quite well manner.

Utilization of white cement bypass dust as filler in asphalt concrete mixtures

This research was carried out to investigate potential reuses of white cement bypass dust (WCBPD) in the Hashemite Kingdom of Jordan. For this purpose, five different asphalt concrete mixtures were prepared using lime mineral filler (control), 2%, 4%, 6%, and 8% WCBPD substitution for lime mineral filler (LMF). The mixtures were subjected to Marshall testing. Results indicated that the substitution of 2% WCBPD for LMF essentially produced almost the same optimum bitumen content (OBC) as the control mixtures (5.5% by weight of aggregate). The substitution of 4% WCBPD slightly increased the OBC to 5.7% by weight of aggregate without any significant negative effect on asphalt concrete properties (stability, flow, voids in mineral aggregates (VMA), and percent of air voids (Pav)). However, further increase in the substitution ratios (6% and 8%) WCBPD was associated with an increase in the OBC to 6.1% and 6.2%, respectively, which makes them uneconomical mixtures. Thus, 4% WCBPD substitution for LMF would be the optimum used in asphalt paving mixtures.

Evaluation of steel slag coarse aggregate in hot mix asphalt concrete

This paper presents the influences of the utilization of steel slag as a coarse aggregate on the properties of hot mix asphalt. Four different asphalt mixtures containing two types of asphalt cement (AC-5; AC-10) and coarse aggregate (limestone; steel slag) were used to prepare Marshall specimens and to determine optimum bitumen content. Mechanical characteristics of all mixtures were evaluated by Marshall stability, indirect tensile stiffness modulus, creep stiffness, and indirect tensile strength tests. The electrical sensitivity of the specimens were also investigated in accordance with ASTM D257-91. It was observed that steel slag used as a coarse aggregate improved the mechanical properties of asphalt mixtures. Moreover, volume resistivity values demonstrated that the electrical conductivity of steel slag mixtures were better than that of limestone mixtures.

METHODOLOGY FOR DETERMINING MOST SUITABLE COMPACTION TEMPERATURES FOR HOT MIX ASPHALT

Using an in-correct compaction temperature of hot-mix asphalt has caused significant problems not only in practice but also in the determination of optimum asphalt content in the design of mix. Asphalt mixture usually looses their temperature during transportation and when laying down. The main objective of this research is to determine the most suitable value of compaction temperature of asphalt pavement that would be use in both laboratory investigations and in field technique Laboratory measurements has been done to find out the effect of various compaction temperatures on the values of the optimum bitumen content and the volumetric properties and Marshal properties of asphalt mixtures. Field measurements were also done to determine the effect of different temperatures of asphalt pavement during laying-down and compaction process on the relative compaction of asphalt mixtures and on the pavement macriotexture. In addition the rate of heat loss of asphalt mixture during transporting it from mixing plant to was determined in both summer and winter seasons. The main conclusion of this investigation is that pavement compaction temperature has a significant effect on the optimum bitumen content (OBC) of asphalt mixtures. Also it has remarkable effect on the values of volumetric properties of hot mix asphalt and Marshall indicators. Field investigations reveal that the Relative Compaction (RC) of the asphalt pavement layer is significantly affected by the temperature of asphalt mixture during compaction and is acceptable up to 110oC. Also, asphalt pavement macrotexture is deeply affected by the value of compacted temperature. A model was developed to relate compaction temperature to the depth of surface texture of asphalt pavement surface. The field results confirmed to a large extent the Laboratory results.

Effects of the manufacturing process on the performances of the bituminous binders modified with EVA

Effects of both addition of commercial EVA and manufacturing mode on the performances of asphalt concrete are investigated. Different concentrations of EVA have been incorporated in either the asphalt cement 80/100 or during the Hot Mix Asphalt Concrete process. Three percentages of EVA by weight of optimum bitumen content estimated at 6% are considered in this study: 3%, 5% and 7%. Softening, penetration and Fraass breaking temperature tests indicate that EVA additions lead to an increase in the stiffness and thermal resistance of the binders. Oxidative ageing induces an increase in the hardness of the modified bitumen. Marshall tests are conducted on three HMAC: the control mix “M0”, the modified binder concrete mix “M1” and the EVA modified asphalt concrete mix “M2”. EVA additions enhance the properties of the control mix which does not satisfy the specifications of Algerian highways. The highest stiffness and the better permanent deformation of HMAC is obtained for 5% of EVA content for both mixes M1 and M2. Although the improvement is less important for M2 than for M1, it is advantageous to use M2 mixes in terms of costs. However the estimation of the optimum bitumen content must be reconsidered to enhance the compactness of M2 mixes.

The effect of polypropylene fibers on asphalt performance

Polypropylene fibers are extensively used in civil engineering applications for many years. These fibers are used in concrete as a three-dimensional secondary reinforcement. Due to adhesion between polypropylene fibers and bitumen, the strengthening mechanism in asphalt concrete is somehow different. In this study, asphalt concrete specimens with polypropylene fibers were manufactured at the optimum bitumen content. It was observed for fiber-reinforced specimens that the Marshall stability values increased and flow values decreased in a noticeable manner. The fatigue life of these specimens was also increased. The improvement of the properties of asphalt concrete shows the positive effect of polypropylene fibers. The fiber-reinforced asphalt mixture exhibits good resistance to rutting, prolonged fatigue life and less reflection cracking. Therefore it is concluded that the application of polypropylene fibers alters the characteristics of asphalt mixture in a very beneficial way.