Using nano silica to enhance the performance of recycled asphalt mixtures

Understanding how the physical properties of Nano-silica material affect the ultimate implementation of the asphalt binder is an essential study area that has been disregarded previously. The current investigation aims to determine whether or not it was possible to change the asphalt binder with Nano-silica (NS) depending on the qualities of the asphalt binder under consideration. Using nano-silica (2, 4, and 6 percentage by weight of asphalt), a penetration grade asphalt cement with 60/70 was developed. Nano silica and asphalt cement were first tested for their qualities. The NS modified asphalt binder was ready for use in the experiment after being heated to 160°C and mixed with a shear mixer at 2000 rpm for 60 minutes. The softening point temperature and penetration index of the NS modified asphalt binder, as well as the Brookfield rotational viscosity and ductility data, were also evaluated. Based on the rheological performance of the NS modified asphalt binder, increasing Nano silica content increases stiffness while decreasing temperature sensitivity. The addition of 4% Nano silica (NS) asphalt binder improved its basic properties and allowed it to be used in hot weather. By adding 4% NS to the hot recycle asphalt mixture, the Marshall stability is increased by 32.5%, the flow is reduced by 21.4%, the unit weight is maintained, and the amount of air voids in the mix, as well as other mix qualities, are kept at acceptable ranges. It'll also boost the ITS by 37.8%. In general, adding NS to asphalt mixtures improves their qualities

Evaluation of structural properties of Baghdad-Baquba road pavements

Structural evaluation of the road pavements is an essential concept to ensure their efficiency to carry traffic loads and to archive the data for future usage especially in major highways. Baghdad-Baquba is an important interstate highway as it connects the capital of Iraq with Diyala governorate which is one of the biggest governorates in Iraq. In addition, this highway connects Baghdad city with several governorates in the north of Iraq. However, this highway exhibits low serviceability due to poor condition of its pavements. Therefore, the structure of the pavements must be evaluated to specify the causes those lead to the decrease in its serviceability and to propose the suitable rehabilitation methods. This study aims to adopt a field survey to extract a number of samples from selected section in this highway to evaluate the structural properties of the pavements based on laboratory testing. Four cores and one pit with 1×1 m dimensions were extracted from the pavements in the field. Several tests were implemented on these tests based on standard methods. The results of the tests were adopted to evaluate the capacity of the pavement based on AASHTO 1993 method. The results exhibited that the estimated applied traffic load exceeded the calculated allowable traffic load by more than 12 times which reflect the disastrous situation. Therefore, the study proposed to rehabilitate the pavements by reconstruction. The study proposed to construct three layers: asphaltic layer with thickness of 240 mm, granular base with thickness of 250 mm, and granular subbase with a thickness of 250 mm. The study stated that all layers must have superior quality with high elastic modulus to resist the predicated traffic load

Deformation behavior of flexible pavements by finite element simulation

Flexible pavement is usually designed based on certain axle load limits and climatic conditions. The Iraqi code has specified certain load limits per each axle type that should not be exceeded. However, many trucks violate these limits by carrying additional weights to decrease the transportation cost. These overweight trucks cause severe deterioration to the pavement and thus reduce its life. The Iraqi authorities generally charges the violating trucks a penalty based on their weights. This penalty could be very small compared to the damage occurring to the pavement based on these over weights. Also, some trucks may carry huge weights that the pavement may not support, so unloading such trucks could be a suitable solution rather than paying few amounts of money and deteriorating the pavement. The study aims at studying the effect of axle load increase, and the variation in pavement moduli, on the overall pavement life. It also aims to estimate the overweight truck limits that could be penalized or unloaded. The research uses the ABAQUS software conditions to estimate the tensile strains occurring under the asphalt concrete (AC) layer and the compressive strains above the subgrade surface. These computed strains are incorporated in the fatigue cracking and rutting models to estimate the pavement life for different axle weights. Results showed that violating trucks should be unloaded when their weights exceed certain limits

Enhancement of Physical Properties of Asphalt Binder by Using Silica Powder

One of the primary requirements for a successful pavement system can be regarded as the caliber of the road pavement. Therefore, various measures have been taken, such as improving pavement quality and structure design methods, to reduce the issues of fatigue cracks and rutting of roads. Since a few years ago, engineers have paid more attention to modifying and improving the performance of asphalt by adding various additives to improve the environment and lower the price of modified pavement mixture. Evaluation of employing modified asphalt cement at various percentages of particle size of silica powder is the main goal of this study. Three percentages of Particle Size of Silica Powder Nano silica and micro silica with 2, 4, and 6% of the weight of asphalt as a modifier for asphalt and their effect on the performance of asphalt mixtures at high temperatures. It was discovered that adding silica powder to asphalt cement would increase the softening point and viscosity and decrease ductility and penetration. Experimental results indicated that the Silica Powder positively contributed to the performance properties of asphalt

Evaluation of Modified Local Asphalt Mixtures by Fatigue Distress Criteria

A fatigue is the accumulation of the materials damage in asphalt concrete mixtures and growing of cracks, under increasing effect of repeated vehicular loading, aging and environment factors, in this research study the effect of temperature, asphalt content, mineral filler, applied Strain, and the polymer (SBS) as a modified asphalt to evaluate their effect on fatigue crack. To achieve the objective of this research, the Nottingham flexural fatigue test is considered and superpave mix design requirements are employed. Test specimens of 380 mm length by 60 mm width and 50 mm height were sawed from slabs of the prepared mixes by rolling wheel compaction. Using Controlled-strain procedure,the tests were conducted at temperatures of 10-20-30 ±1°C and at a frequency of loading of 5 Hz. The full factor design as well, three asphalt contents 4.72, 5.22 and 5.72%, mineral filler (Portland cement, limestone dust), applied strain (400-750µs), and (2-4%) percent of (SBS) polymer, Local material properties, stress level and environmental impacts are considered for this aspect. From the result, it is observed that 2% of SBS modified mixture given a best result due to increase the percent of fatigue life to (120%) as the average when compared with the control mixture, the fatigue life has a positive relationship with asphalt content and temperature when using control strain .The fatigue life of the mixture with limestone dust have result more than mixture with Portland cement,In the general, The fatigue lifeof mixture at 400µs has given result more than 750µs

Performance evolution of novel palm leaf powder used for enhancing hot mix asphalt

Recently, researchers have been moving toward using local waste as an alternative for construction materials. Using these wastes to pave roads is one of the essential recycling methods, which aims to reduce the consumption of natural resources and environmental pollution resulting from the difficulty of decomposing these wastes. In the Middle East, especially in Iraq, Date Palm fiber is widely available as a local waste material. The aim of this research is to evaluate the performance of a developed asphalt mixture with palm leaf powder (PLP) as a partially substituted mineral filler. The Marshall mix design method produced the asphaltic mixes with ordinary Portland cement and PLP as mineral fillers. PLP was included in three rates denoted by 10, 20, and 30% by the weight of the mineral filler. Marshal stability, flow, bulk specific gravity, air voids, voids in mineral aggregates, voids filled with the binder, the indirect tensile strength, and the indirect tensile strength ratio of the PLP mixture were measured and compared with those of the conventional asphalt mixture. Based on the findings of this study, 20% of the Portland cement could be replaced with PLP, at which all of the properties of the enhanced mixture met the requirements of the Iraqi specifications. Then, the asphalt mix with 20% PLP was tested to assess its resistance against fatigue cracks. The results support the usage of waste PLP in pavement construction, enhancing its properties, which would also be very effective as an eco-friendly material

Assessment of potential resistance to moisture damage and fatigue cracks of asphalt mixture modified with ground granulated blast furnace slag

Fatigue and moisture damage have been recognized as the most prevalent problems on asphalt roads, necessitating large annual expenditures for road maintenance. Much industrial waste is added to bitumen paving to enhance its conventional quality while decreasing the negative impacts on the natural environment and increasing resistance to pavement distress. This research uses ground granulated blast furnace slag (GGBFS) to substitute conventional filler (Portland cement [PC]) in hot mix asphalt (HMA). To determine how the GGBFS affects the HMA's susceptibility to moisture and fatigue cracks, Marshall characteristics, tensile strength ratio (TSR), and index of retained strength (IRS) of the asphalt concrete were evaluated. HMA was prepared with different rates of GGBFS (0, 25, 50, 75, and 100%) instead of PC. The data support the usage of 50% GGBFS in asphalt pavements as a partial replacement of PC, which enhanced Marshal stability by 34.4%, reduced flow value by about 12.9%, and increased TSR and IRS by 11.1 and 14.54%, respectively. The fatigue resistance of the modified asphalt mix at the optimum rate was evaluated with the four-point bending beam test; the fatigue life (Nf) increased by 33.8% relative to the reference mixture. The results obtained from this research hold scientific value for researchers and method designers aiming to enhance the resistance of hot asphalt mixtures to moisture and cracking. Using waste materials as an alternative to PC contributes to cost reduction while mitigating the environmental damages associated with cement manufacturing. To summarize, this research highlights the significance of exploring sustainable options in the construction industry, emphasizing the importance of reducing costs, and minimizing environmental impacts

LABORATORY EVALUATION OF MODIFIED ASPHALT WITH SBS POLYMER ON RUTTING RESISTANCE OF RECYCLED PAVEMENT MIXTURE

This research investigates the influence of recycled mixture modified with styrene-butadienestyrene (SBS) polymer on rutting resistance. The reclaimed asphalt pavement (RAP) mixture percentages were used 10, 20 and 30% by weight of original mixture and one percentage of SBS polymer which was 5% by weight of asphalt cement. The moisture susceptibility and rutting were taken into consideration in this study. The results indicated that the recycled asphalt mixture containing on SBS polymer gives better moisture susceptibility and better rutting resistance. It is noted that indirect tensile strength ratio (ITSR) increases when adding SBS with 5% percentage polymer and reaching its maximum ratio 94.5% for 20% RAP and the rut depth decreases by 66.7% when adding SBS with 30% RAP content.http://dx.doi.org/10.30572/2018/kje/100302 

Enhancement of Physical Properties of Asphalt Binder by Using Silica Powder

One of the primary requirements for a successful pavement system can be regarded as the caliber of the road pavement. Therefore, various measures have been taken, such as improving pavement quality and structure design methods, to reduce the issues of fatigue cracks and rutting of roads. Since a few years ago, engineers have paid more attention to modifying and improving the performance of asphalt by adding various additives to improve the environment and lower the price of modified pavement mixture. Evaluation of employing modified asphalt cement at various percentages of particle size of silica powder is the main goal of this study. Three percentages of Particle Size of Silica Powder Nano silica and micro silica with 2, 4, and 6% of the weight of asphalt as a modifier for asphalt and their effect on the performance of asphalt mixtures at high temperatures. It was discovered that adding silica powder to asphalt cement would increase the softening point and viscosity and decrease ductility and penetration. Experimental results indicated that the Silica Powder positively contributed to the performance properties of asphalt

Effect of asphalt modified with waste engine oil on the durability properties of hot asphalt mixtures with reclaimed asphalt pavement

The increased demand for asphalt and other materials involved in the construction of pavement led to an increase in the cost of these materials, which calls for searching for alternatives to virgin materials that can be used to produce asphalt mixtures. Reclaimed asphalt pavement (RAP) was employed in this study and regenerated using oxidized asphalt modified with waste engine oil (WEO). This method can achieve economic and environmental benefits. After improving the properties of oxidized asphalt using WEO, it was used with reclaimed asphalt mixtures (RAP). When the RAP was added at ratios of 20, 30, 40, and 50%, an improvement can be noticed in the mechanical performance of the asphalt mixtures renewed with oxidized asphalt and WEO and an increase in its resistance to stripping. When reclaimed asphalt pavement (RAP) is added to hot mix asphalt (HMA) at concentrations of 20, 30, 40, and 50%, respectively, the Marshall stability of HMA is improved by 10, 20, 28, and 9.5%, the flow is declined by 1% for all ratios of RAP except for 50% RAP where the flow decline by 3%, the unit weight is enhanced, the quantity of air voids in the mix is preserved within allowable ranges, and the resistance to stripping is increased by 62, 77, 85, and 76%, respectively. Research also shows that incorporating 40% RAP enhances the resistance to moisture by about 5.9%. The addition of 40% RAP reduced the Cantabro loss values by about 2 and 16% for both aging and non-aging samples, respectively. The rutting resistance increased by 50 and 47% for mixes with 40% RAP at 50 and 60°C, respectively. As a result, it became evident that mixtures containing RAP material could be effectively adapted to satisfy the relevant volumetric and performance requirements