Durability Evaluation Study for Crumb Rubber–Asphalt Pavement

Effects of Polyethylene Glycol/Porous Silica Form-Stabilized Phase Change Materials on the Performance of Asphalt Binders

The road performance and temperature-regulating properties of asphalt binders modified with novel polyethylene glycol (PEG)/porous silica (PS) form-stabilized phase-change materials (PEG/PS-fs-PCMs) were studied. PS and PEG were used as the supporting substance and PCMs. The results showed that PEG/PS-fs-PCMs could maintain a maximum weight percentage of 70% without leakage, at temperatures as high as 90 °C. The PEG/PS-fs-PCMs exhibited stable chemical structures, excellent thermal stability, high heat storage density, and suitable phase-change temperature. Based on conventional physical tests, the addition of PEG/PS-fs-PCMs can increase the viscosity and the degree of hardness of asphalt binders; thus, achieving an excellent comprehensive performance of the modified asphalt binder depends on determining the optimal dosage of PEG/PS-fs-PCMs. Additionally, incorporating PEG/PS-fs-PCM particles into the asphalt binder can enhance its ability to withstand permanent deformation at elevated temperatures, while PEG/PS-fs-PCMs mainly act as a filler, weakening the cohesive force of the asphalt molecules, and preventing the ductility of asphalt from expansion, according to DSR and BBR tests. Moreover, the use of PEG/PS-fs-PCMs can enhance the heat transfer properties of the asphalt binders, resulting in an improved temperature regulation performance. However, the accumulation of PEG/PS-fs-PCM particles on asphalt binders can negatively impact the storage stability of the modified asphalt binders, because of the difference in density between the two materials.

A systematic review of the utilization of waste materials as aggregate replacement in stone matrix asphalt mixes

The daily utilization of a large amount of raw materials is causing a rapid depletion of natural resources. The growth of the human population is accompanied by higher activities in the agricultural and manufacturing sectors that resulted in a larger volume of waste materials being disposed of in landfills each year. Researchers are seeking ways to reduce the adverse impact of waste materials on the environment. One method for managing waste materials is using them as a substitute for natural materials, for example, as aggregate replacement in the construction of road pavements. This paper reviews the previous studies that explored the use of waste materials as aggregate replacement in stone matrix asphalt (SMA) mix and the performance of asphalt pavements constructed using these materials. A systematic literature search of four databases revealed that waste materials could be used as an alternative to the natural aggregates. Future studies on the SMA mixes should investigate using other waste materials that could improve mix design and enhance pavement performance. There is a need to establish a standard code of practice and train material technologists to use different types of waste in SMA pavement construction. In summary, it is essential to perform a life cycle cost analysis (LCCA) and life cycle assessment (LCA) to quantify the economic and environmental impacts of the different waste materials used as aggregates in SMA.

Improvement the Shear strength of Asphalt Mixture by using crumb tire Rubber

Rutting is one of the big problems in hot-mix asphalt (HMA) pavements. The primary mechanism of HMA rutting is shear deformation, often caused by high stress in HMA layers during traffic loading, especially at high temperatures. Current HMA rutting tests are not necessarily designed to capture HMA shear properties such as shear strength, shear strain, and shear module. The present work explores the behavior of the shear strength properties of HMA modified with Crumb Tire Rubber (CTR) and two types of filler (brick and lime dust in comparison with passing sieving No.200 as control filler) by developing a Simple Punching Shear Test (SPST) under control of temperature and loading rate. A series of laboratory sample tests to formulate and set up the SPST protocol and the related test parameters, derive the SPST results analysis sample to capture the HMA shear parameters from the results and comparatively evaluate the shear properties of HMA mixes. Results have shown that the SPST is relatively receptive to the form of modifier and filler. Using limestone dust as with (5%) CTR content increased higher shear strength, the rate of increase was about (44.44%) and (51.38%). Also 5% to 7% CTR content with lime dust filler lowering shear strain more than for brick dust filler.

Improvement shear properties of HMA using crumb rubber with different filler

Rutting is one of the big problems in hot-mix asphalt (HMA) pavements. The primary mechanism of HMA rutting is shear deformation, often caused by high stress in HMA layers during traffic loading, especially at high temperatures. Current HMA rutting tests are not necessarily designed to capture HMA shear properties such as shear strength, shear strain, and shear module. The present work explores the behavior of the shear strength properties of HMA modified with Crumb Tire Rubber (CTR) and two types of filler (brick and lime dust in comparison with passing sieving No.200 as control filler) by developing a Simple Punching Shear Test (SPST) under control of temperature and loading rate. A series of laboratory sample tests to formulate and set up the SPST protocol and the related test parameters, derive the SPST results from the analysis sample to capture the HMA shear parameters from the results, and comparatively evaluate the shear properties of HMA mixes. Results have shown that the SPST is relatively receptive to the form of modifier and filler. Using limestone dust as with (5%) CTR content increased higher shear strength, the rate of increase was about (44.44%) and (51.38%). Also 5% to 7% CTR content with lime dust filler lowering shear strain more than for brick dust filler.

A Review of the Utilization of Coal Bottom Ash (CBA) in the Construction Industry

One effective method to minimize the increasing cost in the construction industry is by using coal bottom ash waste as a substitute material. The high volume of coal bottom ash waste generated each year and the improper disposal methods have raised a grave pollution concern because of the harmful impact of the waste on the environment and human health. Recycling coal bottom ash is an effective way to reduce the problems associated with its disposal. This paper reviews the current physical and chemical and utilization of coal bottom ash as a substitute material in the construction industry. The main objective of this review is to highlight the potential of recycling bottom ash in the field of civil construction. This review encourages and promotes effective recycling of coal bottom ash and identifies the vast range of coal bottom ash applications in the construction industry.

Application of Atomic Force Microscope to Investigate the Surface Micro-Adhesion Properties of Asphalt

The surface energy and bonding coefficient of asphalt are important factors that affect the adhesion performance of asphalt/aggregate. In this study, the micro-bee-like-structure of asphalt and force curves between the microscope-probe and asphalt were measured via atomic force microscopy (AFM). To investigate the influence of asphalt properties on micro-adhesion of asphalt, five types of asphalt were used in four states: original, aged at 163 °C, immersed in water and added anti-stripping agent. The results demonstrate that the surface energy of grade 90 asphalt is greater than that of grade 70 asphalt when oil source is the same and that of modified asphalt is greater than matrix asphalt. The surface energies and bonding coefficients of asphalts decreased after aging and immersion. The surface energies of asphalts were greatly improved by adding anti-stripping agent and the bonding coefficients of the asphalts increased by 5.04–37.14% after adding an anti-stripping agent.

Silane Modification of Crumb Rubber on the Rheological Properties of Rubberized Asphalt

Because there is a lack of studies on rubberized asphalt based on silane coupling agent modification, KH-550 modified crumb rubber and rubberized asphalts incorporating normal rubber and modified rubber were prepared, respectively. The rheological properties of asphalt samples were evaluated by a dynamic shearing rheometer and a bending beam rheometer; then, mechanisms of KH-550 on rubber surface and functional group changes were analyzed by a Brunauer–Emmett–Teller specific surface area measurement and a Fourier transform infrared spectroscopy. The results imply that: (i) rubber surface area rises and chemical reactions accrue between rubber and asphalt; (ii) modified rubber achieves a more stable state within asphalt, which helps to enhance the mechanical properties of asphalt; (iii) modified rubber helps asphalt to dissipate stress so as to resist the formation of cracks and deformation under low temperature conditions.