VIOLATION OF PUBLISHING ETHICS. Development study in the laston mixture of buton asphalt wearing course with the addition of carrageenan to identify crack resistance

The Georgia Department of Transportation (GDOT) implemented the corrected optimum asphalt content (COAC) approach to reducing the allowable reclaimed asphalt pavement (RAP) binder contribution for improving mixture durability. The COAC of 60:40 implemented in 2019 allows 60% of the RAP binder to be credited to the total mix, requiring additional virgin asphalt binder equivalent to 40% of the RAP binder to be added to the volumetric optimum binder content. To further enhance the durability of asphalt mixtures, GDOT plans to implement the indirect tensile asphalt cracking test (IDEAL-CT) in the balanced mix design (BMD) method in conjunction with the Hamburg wheel tracking test that is currently specified in the GDOT specifications. To assist GDOT in the implementation effort, this study was conducted to (1) evaluate the effect of the COAC approach on the cracking and rutting resistance of asphalt mixtures using the proposed BMD test methods; and (2) benchmark the cracking resistance (i.e., CTindex) of plant-produced mixtures being produced in the state of Georgia for developing CTindex thresholds for future implementation. The results of this study suggest that the 60:40 COAC helps improve the cracking resistance of asphalt mixtures containing high RAP contents with minimum effect on their rutting resistance when compared with the corresponding virgin mixtures. In addition, because of statistical differences in the CTindex results between stone mastic asphalt (SMA), surface, and intermediate/base mixtures tested in this study, different CTindex thresholds are proposed for these three mixture groups for pilot projects. Further research is anticipated to refine these thresholds and verify with field performance for future implementation in mix design approval and acceptance testing.

The paper aims to investigate the influence of basalt fiber (BF) on the crack resistance of the asphalt mixture and conduct a mechanical analysis. First, two typical asphalt mixtures, namely AC-13 and SMA-13, were designed. The impact of BF on the mixture design results was analyzed. Then, several macroscopic tests, namely the four-point bending test, indirect tensile test, and semicircular bending test (SCB), were conducted to assess the effect of BF on the cracking resistance of asphalt mixtures. Finally, the influence of BF on the cracking resistance of asphalt mixtures was analyzed based on an environmental scanning electron microscope (ESEM) observation. The results show that: (1) BF increases the optimal asphalt content of AC13 and decreases the optimal asphalt content of SMA-13, which is caused by the different asphalt-absorption capacity of BF and lignin fiber (LF). (2) BF enhances both the fatigue crack resistance and temperature crack resistance of asphalt mixtures. The enhancement on the SMA-13 is more significant, indicating that the enhancement of BF on asphalt mixtures is related to the type of aggregate gradation. (3) BFs in the asphalt mixture lap each other to form a spatial network structure. Such structure can effectively improve the crack resistance of the mixture by dispersing the load stress and preventing the flow of asphalt mastic. The study results provide an effective method to design crack-resistant asphalt mixtures.

Enhancing low-temperature crack resistance: A method for establishing meso-models and evaluating steel fiber-reinforced hot recycled asphalt mixtures

In order to study the influence of different aging conditions on the low-temperature crack resistance and water stability of polyester fiber asphalt mixture. Prepare standard Marshall specimens of asphalt mixture with 0.4% polyester fiber doping, and carry out water immersion Marshall test and low temperature splitting test through indoor asphalt mortar aging, asphalt mixture short-term aging and long-term aging. The results show that: under the three aging conditions, when the water immersion and low temperature time are fixed, with the increase of the aging degree, the water stability and low temperature crack resistance of the asphalt mixture decrease. When the immersion time is 2 h, the stability of asphalt mortar aging and short-term aging decreases by 6.0% and 11.8%, respectively, compared with unaging, but the long-term aging is only 3.6% lower than the short-term aging. When the temperature is −5 °C, the split tensile strength of asphalt mortar aged and short-term aged increases by 4.24% and 14.35%, respectively, compared with unaging, while long-term aging only increases 4.18% compared with short-term aging. This indicates that the short-term aging condition has the most significant effect on the water stability and low-temperature crack resistance of polyester fiber asphalt mixes. At the same time, this study established a regression equation between the test temperature and the low temperature evaluation index through quadratic fitting (the correlation coefficient is 0.960–0.998), and the regression relationship can be used to estimate the low temperature evaluation index at different test temperatures.

Low-temperature crack resistance of coal gangue powder and polyester fibre asphalt mixture

Effect of fibres addition on the physical and mechanical properties of asphalt mixtures with crack-healing purposes by microwave radiation

Currently, many countries are facing a dangerous challenge due to shortage in the virgin materials used in highway construction. This problem increases with time as a result of constructing new roads as well as maintaining the existing road network. In addition, construction costs, and oil and fuel prices escalates tremendously in the last few decades. Thus, reusing old pavement materials (reclaimed asphalt pavement, RAP) in new construction gains the attention of researchers and practitioners. Although pavement recycling is widely practiced in the advanced countries, it is still relatively new in the developed countries. One of the major advantages of using the recycled asphalt pavement is that it decreases both the quantity of aggregate and the quantity of asphalt required. The main purpose of this research was to investigate the influence of using reclaimed asphalt pavement (RAP) materials on the performance of asphalt concrete mixtures containing RAP. Another objective of this study was to determine the maximum RAP Hissan Al-Kandari percentage that can be added to a new Hot-mix asphalt (HMA) mixture without a significant effect on the mixture performance. A total of five asphalt mixtures containing different percentages of RAP from old pavements in Kuwait were investigated. Marshall tests were conducted on these mixtures to determine the optimum asphalt content according to Kuwait specifications. Asphalt concrete specimens were then prepared at the optimum asphalt content resulted from Marshall tests to investigate the influence of the percentage of RAP in the mixtures on the cracking and rutting resistance through the indirect tensile test and the wheel tracking test. Results showed that, using up to 25% RAP yields about 3.6% reduction in the optimum asphalt content as well as saving in the virgin aggregate without a significant influence on the mixture performance. Furthermore, using more than 25% RAP in the asphalt concrete mixture yields a significant reduction in the mixture performance (resistance to rutting, cracking, stability and flow).

Evaluation and design of fiber-reinforced asphalt mixtures

Cold Bituminous Emulsion Mixtures (BEMs) means manufacturing of asphalt at ambient temperature using bitumen emulsion as the binder. It has been widely utilised in many countries such as the USA and France. The use and development of BEMs were not brought forward in the UK due to the country’s relatively wet/cold climatic conditions, which are not favourable to the application of cold BEM in terms of the long curing process and low early strength. Decreasing wastes from aggregate production processes, reducing land-filling and reducing CO2 emissions during hot bituminous mixture production and laying are the main target schemes for the environmentally friendly processes. Cold BEM is one of the attractive methods of producing bituminous mixtures to tackle the mentioned disadvantages when incorporating some waste and/or by-product materials individually or collectively into these mixtures. Recently, researchers have shown an increased interest in incorporating supplementary cementitious materials (SCM) in production of BEMs in the UK and around the world. Three benefits can be stated when using SCM in BEMs; these are upgraded mechanical properties, gaining economic advantage and the ecological advantage factor. Mainly due to some inherent problems associated with the performance of the pavement produced by the BEMs process, they are regarded as “inferior” to conventional HMA. The major problems with this kind of application are the long curing time (evaporation of trapped water) required to achieve the required performance, the weak early life strength (because of the existence of water) and high air voids content. The full curing in the field of these mixtures may occur between 2−24 months depending on the mixture’s ingredients and weather conditions. Considering the above disadvantages, this study investigated the possible ways of developing a new BEM/s with gap graded mixtures similar to the conventional Hot Rolled Asphalt (HRA) gradation. HRA is extensively used for surfacing major roads in the UK because it provides a dense, impervious layer, resulting in a weather-resistant durable surface able to endure the demands of today’s traffic loads and providing good resistance to fatigue cracking. The mentioned new product is termed Cold Rolled Asphalt (CRA). The main aim of this study was to investigate producing high strength, fast curing and sustainable CRA mixtures for heavily trafficked road and highway surfacing layers by using different waste and by-product materials (normally used as SCM) individually and/or collectively as a replacement for conventional mineral filler. To achieve the above aim, four SCMs have been used which were: Waste Paper Sludge Ash (WPSA), which has high lime and gelenite content, Poultry Litter Fly Ash (PLFA), which has high alkali components, Silica Fume (SF), and Rice Husk Ash (RHA), which is high silica content and cost-plus material, collectively instead of conventional mineral filler. In addition, besides the production of the new high-quality CRA mixtures, the research includes a detailed comparison study of conventional HRA mixtures, CRA mixtures containing conventional mineral filler and CRA mixtures containing hydraulic filler, i.e. Ordinary Portland Cement (OPC). This laboratory study was conducted by utilising different types of testing and curing and conditioning methods to characterise the mechanical properties and durability of the produced CRA mixtures. Indirect Tensile Stiffness Modulus (ITSM), Uniaxial Compression Cyclic Test (UCCT), Four Point Bending fatigue test on prismatic shaped specimens (4PB) and Semi-Circular Bending monotonic test (SCB) were used to assess the mechanical properties of these mixtures while Stiffness Modulus Ratio (SMR) and Long Term Oven Aging (LTOA) were used to investigate the main durability features, i.e. water sensitivity and long-term aging, respectively. Furthermore, Scan Electron Microscopy (SEM) technique and X-Ray Diffraction (XRD) analysis have been used to investigate the reasons behind the improvement in the mechanical properties of the novel mixtures. By means of ITSM results, four high-qualities CRA mixtures have been optimised which are: CRA-WPSA (containing 6% WPSA), CRA-BBF (containing 4.5% WPSA+1.5% PLFA), CRA-TBF-1 (containing 3.75% WPSA+1.25% PLFA+1% SF) and CRA-TBF-2 (containing 3.375% WPSA+1.125%PLFA+1.5% RHA). Stiffness modulus of CRA mixtures increases significantly by replacing the conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2, especially in the early curing time (less than 7 days), which is the main disadvantage of the cold BEMs. Also, the target stiffness modulus, which is the ITSM for 100/150 HRA (approximately 2000MPa), was achieved after 4 hours for the produced fast-curing CRA mixtures, i.e. CRA-TBF-1 and CRA-TBF-2, under the normal curing method (24 hours in the mould then leave the samples at 20 oC). In addition, the replacement of conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2 greatly improves the permanent deformation resistance and fatigue life when compared with the control CRA and the traditional HRA mixtures.

Evaluation of Asphalt Mixture Containing Coal Ash

Economic growth. Most of the existing road surface layers in Indonesia use Flexible Pavement. The fundamental problem in road construction is road damage before the planned age is reached, the factors that cause road damage can be caused by the influence of weather and water, causing asphalt aging and durability of road pavement to be damaged. The purpose of this study was to determine the Durability and Aging of Pracampur Asphalt Buton (ASBUTON) with Variations in Soaking Time by conducting experiments conducted in the laboratory through Marshall Test testing with reference to the general specifications of bina marga 2018. Short - Tern Aging (STOA) test specimens were made by heating the specimens in a loose state at 135oC for 4 hours before compaction, while Long- Tern Oven Aging (LTOA) test specimens were made by heating the specimens for 2 days at 85oC after the specimens were compacted. Durability parameters of AC-WC mixtures were observed from the residual strength index (IKS), first durability index (IDP) and second durability index (IDK). Based on the premixed asbestos mixture in the AC-WC layer, the optimum asphalt content (KAO) of 6.25% was obtained. The IKS of Normal, STOA, and LTOA specimens were 98.97%, 98.21%, and 97.69%, respectively. Furthermore, the IDP of Normal, STOA and LTOA specimens obtained r values of 0.7%, 0.11%, and 0.15%, respectively. While the IDK of Normal, STOA and LTOA test specimens obtained values of 1.53%, 2.64% and 3.41%, respectively, while the SA value of Normal, STOA and LTOA test specimens at 48 hours immersion is 98.47%, 97.36%, and 96.59%, respectively. After 48 hours of immersion at 60oC, it tends to decrease or lose strength for all test specimens and conditions. The STOA test specimen at 48 hours of immersion experienced a significant decrease of 89.83% so that it did not meet the specifications specified in the 2018 Bina Marga Specification of 90%.

For the better understanding of fracture test method to evaluate the crack resistance of asphalt mixtures, the current test methods and evaluation indexes were theoretically and experimentally compared, including the indirect tensile test, single edge notch beam test, semicircular bending test (SCB) and disk-shaped compact tension test. The stress intensity factors for different tests were compared, and the appropriate range of notch depth was determined. The SCB was finally selected as the test method for evaluating the crack resistance of the asphalt mixtures. According to the relationship between the fracture energy and notch depths, the essential fracture energy of asphalt mixtures was calculated, and it was recommended as the evaluation index of asphalt mixtures for crack resistance. Furthermore, the failure process of the SCB was analyzed, and the contraflexure point on the load–displacement curve was found and defined. The fracture energy at the contraflexure point could be used to evaluate the ultimate crack resistance of the asphalt mixtures. The application of the essential fracture energy and the contraflexure point can correspond to the actuality of the asphalt pavement, which provides a reference for the crack resistance research of asphalt mixtures in the future.

This study focuses on the effects of the production temperatures, warm mix asphalt (WMA) additive, and fiber content on the cracking resistance of steel- and glass-fiber-reinforced asphalt mixtures. By using three different approaches, which included different mixing and compaction temperatures, along with the incorporation of a WMA additive, the samples were produced utilizing the Marshall mix design method. The low-temperature cracking resistance and bottom-up fatigue cracking resistance of the asphalt mixture samples were assessed through indirect tensile (IDT) tests performed at two different test temperatures: −10 °C and 20 °C, respectively. According to the fracture work density values, glass fibers significantly improve the low-temperature cracking performance of asphalt mixtures. Furthermore, it was found that the low-temperature cracking resistance of the hot mix asphalt (HMA) mixtures containing fibers was similar to that of the mixtures prepared using the WMA additive at 15 °C lower mixing and compaction temperatures than the HMA mixtures. To conclude, the WMA additive improved the compactability of the steel- and glass-fiber-reinforced asphalt mixtures without compromising the low temperature cracking performance, despite the low mixing and compaction temperatures.

The cracking resistance of asphalt mixture is a non-negligible issue. However, the cracking resistance evolution law, motivated by two factors (thermos-oxidative aging degree and test temperature), is not yet well understood. The aim of this investigation is to gain more insight into the effect of thermos-oxidative aging and test temperature on the cracking resistance of asphalt mixture. Asphalt mixture (AC-13) and stone mastic asphalt mixture (SMA-13) were selected and exposed to different thermo-oxidative aging degrees (unaging (UA); short-term thermo-oxidative aging (STOA); long-term thermo-oxidative aging for 2/5/8 days (LTOA2d/LTOA5d/LTOA8d)). A direct tension test at different test temperatures (10 °C, 20 °C, 30 °C, 40 °C) was adopted to obtain their stress–strain curves and evaluation indexes (tensile strength, ultimate strain, pre-peak strain energy density, and post-peak strain energy density). The comprehensive index-cracking resistance index (CRI) was established by the entropy weight method combined with the technique to order preference by similarity to ideal solution (TOPSIS) method and the corresponding aging coefficient was determined. The results showed that STOA can increase the aging coefficient of asphalt mixture, thereby boosting the cracking resistance. Additionally, the effect can be weakened by elevations in the test temperature. Meanwhile, LTOA can decrease the aging coefficient and thereby weaken the cracking resistance. This effect becomes more prominent with elevations in the test temperature. SMA-13 possesses a superior cracking resistance to AC-13, with a gap in CRI value of 3–69%, regardless of the aging degree and test temperature. A good relationship exists between the aging coefficient and the two factors (aging degree and test temperature).

Laboratory evaluation of oak ash waste for use in hot mix asphalt modification