Curved girders are widely used in bridge construction to overcome geographical obstacles. In such cases, girders with a box cross-section are preferred due to their large flexural and torsional rigidity. Internal diaphragms are used to limit cross-section distortion and the distortional warping stress induced in the box girders. However, the use of such diaphragms hinders girder maintenance. To facilitate the maintenance process, typical cross frames such as X- or V-shape truss members are used. Alternatively, access holes are provided in the solid plate diaphragms. In this paper, finite element models for horizontally curved box girders were constructed and topology optimization method was used to obtain the optimal shapes for the internal and external diaphragms. In this analysis the optimization objective was set to reduce the diaphragm mass while maximizing its rigidity. The mass retained percentage was assigned to various values from 20% to 40%. The deformations and distortional stresses induced in the girders were compared between girders having solid plate diaphragms and girders with optimized cross-frame diaphragms. The parametric study included the cross-section aspect ratio and curved girder central angle as they have large effect on distortional warping stresses. The results showed that the increase in distortional warping normal stress was less than 4% and the increase in the cross-section distortion angle was less than 37% between optimized diaphragms and solid plate diaphragms. The optimized diaphragms were then simplified into more practical configurations that differed depending on the girder aspect ratio. The simplified diaphragms were then tested against the optimized diaphragms for girders with different numbers of internal diaphragms to check its practicality.

The pervious cement concrete (PC) or Permeable concrete is a special type of concrete with no or little sand, which exhibited an excellent hydrological function in decreasing the water runoff. However, accurate prediction of its water permeability coefficient using the Constant Head Method (CHM) is still unreliable due to the previous models have been established using a small size of PC samples, also these models have not been evaluated so far to understand its behavior in a large database. Thus, the authors think that the convenient time to propose a reliable model to predict the water permeability of PC, especially in the existence of large experimental PC Samples in literature. In this study, the experimental data of PC from (2016–2021) that was conducted in the previous work has been collected to build a database of the PC samples, which calculated the permeability coefficient using CHM. This effort provides …

Most of the pavement distress in warmer regions is due to rutting and moisture damage. As a result, additives are now required to enhance the properties of asphalt binders and mixtures. The influence of nano titanium dioxide (TiO₂) modification on the physical and rheological characteristics of the asphalt binder, as well as the rutting performance of Hot Mix Asphalt (HMA), was investigated in this study. The modified binders were evaluated by Bending Beam Rheometer (BBR), the Dynamic Shear Rheometer (DSR) Pressure Aging Vessel (PAV), Rolling Thin Film Oven Test (RTFOT), and Multiple Stress Creep Recovery (MSCR) test. After aging the modified binder over short and long periods, potential rutting was evaluated. Non-recoverable compliance (Jnr) was assessed for early aging. The MSCR and the Superpave system were used to evaluate the performance grade of binders. The stiffness of modified binders was also measured at low temperatures. Rutting resistance was evaluated for HMA specimens containing nano TiO₂ by the Hamburg Wheel Track Device (HWTD). Several percentages of nano TiO₂ (1.5%, 3.5%, 5.5%, and 9%) were used to enhance the characteristics of 60–70 asphalt binder. The results revealed that nano TiO₂-modified binders enhanced the rheological and physical properties of unaged and aged asphalt binders. The findings also showed that nano-TiO₂ increased the rutting resistance of asphalt mixtures. The statistical analysis indicated that the nano TiO₂ modification significantly improved all tested properties of the base asphalt binder, however, the stiffness and Jnr difference were found insignificantly influenced by the incorporation of the nano TiO₂.

There is significant evidence that utilizing polymers improves asphalt cement characteristics, preserve the environment, and increases industrial-economic benefits. Consequently, the use of such modifier in asphalt cements via sustainable technology is strongly encouraged. The major goal of this research is to study the effect of modified asphalt cement with crumb rubber (CR) (10%, 15%, and 20% CR) and recycled polyethylene terephthalate (rPET) (1.5%, and 2.5% rPET) on the physical and rheological characteristics of asphalt cements. Asphalt cement experiments such as softening point, penetration, and rotational viscosity (RV), were performed on both the virgin and modified asphalt cements. The effect of CR and rPET on the temperature sensitivity of the asphalt cement was also evaluated by checking the penetration index (PI), penetration viscosity number (PVN), viscosity-temperature sensitivity (VTS), activation energy flow methods (AE) of all the modified asphalt cements. The rutting index (G*/sin δ) was calculated using Bari and Witczak model. The findings revealed that the addition of CR and rPET in the asphalt cement reduced the temperature sensitivity and enhanced the rheological characteristics of the asphalt cements. Moreover, incorporating the CR and rPET into virgin asphalt cements increased the high temperature performance of all percentage of CR and 2.5% WP modified asphalt. There was a considerable correlation between temperature sensitivity methods; PI, PVN, VTS, and AE. Finally, virgin asphalt modified with CR is better than rPET.

The increase in the cost of virgin materials and the environmental sustainability have contributed to increasing the incentive to use asphalt mixtures containing high percentages of recycled asphalt pavement (RAP). However, the use of high percentage of RAP into virgin asphalt mixture could negatively affect the performance of some properties of asphalt mixtures. Thus, using an appropriate additive to offset the negative effect of RAP could lead to an increase in the amount of RAP in asphalt mixtures. Therefore, this study aimed to evaluate the effect of using glass fiber (GF) with different contents (0.0%, 0.1%, 0.2%, and 0.3%) as an additive on the performance of asphalt mixtures containing RAP materials (60%, 70%, and 80%) and rejuvenated with waste engine oil (WEO) i.e., 6%, 9%, and 12%. The performance of RAP mixtures incorporating GF was evaluated using the indirect tensile strength test (ITS), resilient modulus test, and moisture susceptibility test. Hamburg wheel track testing was done to evaluate the rutting performance of the 70% RAP mixture. The results showed that the GF modification enhanced the ITS, rutting resistance, moisture susceptibility, and resilient modulus of rejuvenated mixtures. It was also found that the GF content of 0.2% was the optimum.

Sb₂O₃ nanoparticle was selected as it is expected to reduce the aging effect on bitumen, and is a novel material hasn’t studied yet in the literature. Bitumen was modified by antimony trioxide (Sb₂O₃) nano particle. The rutting performance of Sb₂O₃ modified bitumen and the performance of Hot Mix Asphalt (HMA) was investigated. Multiple stress creep recovery (MSCR) test was performed. HMA mixtures were tested using the Indirect Tensile Strength (IDT) test. HMA mixtures were aged in the oven for short and long-term aging before conducting Hamburg Wheel Tracking (HWT) test to determine the rutting performance of the HMA mixtures. After aging, Sb₂O₃ modified bitumen becomes more resistive according to the results of both the bitumen and HMA tests. As a result, three percent Sb₂O₃ modified bitumen had better performance similar Jnr and R%. The best rutting performance was determined for 3% Sb₂O₃ modified bitumen with 4.3 mm rut depth.

This research focused on predicting the performance of modified asphalt mixtures with high contents of nano-silica fume (NSF) using AASHTOWare Pavement ME Design software, which is the production version of the Mechanistic-Empirical Pavement Design Guide (MEPDG). The NSF was completely mixed with the virgin asphalt using a high-shear mixer at 160 °C and a speed of 2000 rpm for 1 hr. The physical- rheological properties of the control binder, as well as the binders modified with 30, 40, and 50% NSF by asphalt weight, were determined. The asphalt mixtures were prepared using control and NSF-modified binders by the conventional Marshall method. The predicted field pavement performance of both the control and NSF-modified asphalt mixtures in terms of rutting, longitudinal cracking, alligator fatigue cracking at three different climatic locations in Egypt (Aswan, Cairo, and Alexandria), and three design speeds (10, 55, and 95 kph) was evaluated. The simulations indicated that the NSF-modified mixtures outperformed the control mixture.