This research aims to evaluate the mechanical properties of hot asphalt mixtures prepared using modified asphalt binders with various contents of nano-silica fume (NSF). The modification to virgin bitumen is done by shear mixing with NSF at low contents (2, 4, 6, and 8%) and high contents (20, 30, 40, and 50%) with bitumen weight. The homogeneity of the modified asphalts was assessed using Scanning Electron Microscopy. The rotational viscosity, softening point, and penetration tests were used to evaluate the rheological-physical properties of the modified asphalt binders. The stiffness, moisture damage, rutting, and fatigue of the hot mixes prepared with NSF-modified binders were evaluated using Marshall, indirect tensile strength, and double punching tests. The results showed a significant improvement in the rheological-physical properties of the modified binders with high content compared to low content of NSF. Therefore, the modified binders with 30%, 40%, and 50% of NSF were selected to prepare NSF-modified mixtures. The results showed that asphalt mixtures incorporating 30, 40, and 50% NSF-modified binders were more resistant to moisture damage, rutting, and fatigue cracking compared to the control mixture. The novelty in this research is to produce a modified asphalt mixture with two-thirds a quantity of bitumen while achieving a high performance compared to the control mixture.

The concept of sustainability is considered essential in the development of the asphalt mixtures  industry, due  to its economic  and  environmental  benefits.  This  study  attempts  to highlight  the  potential  benefits  of  sustainability  using  Reclaimed  Asphalt  Pavement  (RAP). It reviews previous studies conducted on RAP to obtain the most important characteristics in how to  use  the  optimal content of  RAP  and  its  effect  on  some  basic  properties  such  as  resilient modulus, susceptibility to moisture,  permanent  deformation, and  fatigue.   This  study  mainly focuses on  the  advantages of  using  RAP materials in  hot  mix  asphalt  (HMA). The  results indicated that adding 30% of RAP to virgin asphalt mixtures gives the best performance in terms of the most studied characteristics. 

he increase in the amount of reclaimed asphalt pavement (RAP) and environmental concerns for bitumen production have contributed to the  use of RAP in road construction and maintenance.  The  use  of  higher  than  15%  of  RAP  adversely  affects  the  physical  and rheological  properties  of  the  asphalt  binder  and  the  mechanical  properties  of  mixtures. Therefore,  the  use of bitumen  and  asphalt  mixture  improver  were  necessary  to  reduce  the negative  effects  generated with  the use  of RAP.  This  paper  aims  to  study  the  effect  of fiberglass (FG) (0.5%,  1.0%, 1.5%,  and 2%) on the  mechanical  properties of asphalt concrete containing  25%,  50% RAP and  9%  waste  engine  oil. The  performance  of  RAP  asphalt mixtures  incorporated  with FG was evaluated using  the Marshall  stability test,  moisture susceptibility  test,  and immersion wheel rutting  test. The  results indicated that the  use  of FG and  RAP  materials  to  rejuvenated asphalt  mixtures resulted  in  an increase  in  the values  of Marshall  stability  and  rutting  resistance. Moreover,  the  study revealed that  increasing  the content of RAP material and FG results in increased resistance of asphalt to moisture damage. This paper concluded that using 0.15% of FG and 50% RAP materials gives the best results

The dimensions of many water streams, which satisfy the proper hydraulic condition, may not be compatible with the designed dimensions of an irrigation work needed to be constructed in some locations. The design requirements of such irrigation works may need to make a contraction in the channel width in the location of constructions. This contraction, of course, affects the different flow properties and the scour hole formed downstream these structures. So, the present experimental study aims to investigate the effect of the transition angle and the contraction ratio on the flow properties and on the scour phenomenon downstream water structures. Through 454 experimental runs, carried out on 20 experimental models, the study proved that, for an efficient hydraulic performance and economic design, the best transition angle (θ) for the approaches of water structures is 30° with a contraction ratio (r) not less than 0.6.

In the conditions of severe climatic changes that are sweeping the world now, causing many problems, of which high surface water levels, torrential rains and floods are among the most dangerous phenomena. Since dams are the most engineering and structural protection means that engineers resort to, to protect against these dangers in such circumstances, not to mention the other important uses of dams such as storing water for irrigation purposes, generating electricity, feeding the underground reservoir, or diverting flow paths for any engineering purpose. Dams are usually classified on the basis of several considerations, including solid dams of different types, and flexible dams. Flexible dams, which are sometimes called earth dams, are of a special nature as they consist mainly of loose materials of a special porous nature and different ratios of interspaces that allow water to pass through them and penetrate the dam body in different proportions, which, if not prevented or avoided, may lead to the collapse of the dam body. In the present study a numerical analysis of seepage through zoned earthen dams is introduced, as they are the most popular type of flexible dams, to clarify the behavior of the streamlines of the seepage water through the body of such type of dams with different types of used soil of filling materials. Decreasing the relative permeability coefficient between the inner and transition zones up to 0.001 caused a significant decrease in the different seepage properties, after that, the effect was minor.

The compatibility between the needed structural designed dimensions of the irrigation works and the dimensions of the water stream or the canal in which the irrigation work will be located has a great importance from more than one point of view. As it is well known, the main aim of the designer of such works is to reach the optimum design for maximum performance efficiency with economical cost, and minimize negative technical impacts that may be harmful to the safety of the whole work. Since the complete suitability between the obtained designed dimensions of the different construction elements of the work, and the original properties and dimensions of the canal in which the work will be constructed, is rarely occurring. The designer always has to make some changes in the original engineering properties and dimensions of canals, such as bed width, bed level, and/or inside side slope, to reach the needed suitable compatibility between the structural design and the natural original canal cross section. For the economical purposes, the design always needs less width of the work, than the width of the bed of the original stream cross section, so a contraction may be needed where the work will be constructed; the literature indicated that, such a contraction must not be less than 0.6 of the original bed width. That contraction, of course, has a direct impact on the different hydraulic parameters, such as water depth, velocity, and flow regime in the location of the work. Changes of such hydraulic parameters may exceed their safe permissible values, and so the whole structure may face some dangerous situations, which must be overcome. In this paper, we present a technical survey of the previous research concerning canal width contraction, with the needed technical comments, and comparisons as a logical approach for a master-thesis under the same title.

This paper is intended to determine the space-charge-free field on the stressed discharge wires’ surface, the corona-onset voltage of wire-duct electrostatic precipitators (ESP) as influenced by the variation of the velocities of the incoming flow gases. The corona current-voltage (I-V) characteristics of wire-duct ESP is calculated under varying velocities of incoming flow gases. The calculation is made using the improvement of Deutsch’s Method. The method is endorsed by an iterative process to determine an estimate for the underlying dissemination of the charge density close to the surface of the stressed discharge wire(s). The electric potential, field, space-charge density in the interelectrode spacing, corona onset voltage and current-voltage characteristics of the precipitator are considered. Besides, the effect of gradually increase of the velocities of incoming flow gases, changing the number of stressed wires and …

Abstract: Several models of multi-criteria decision-making (MCDM) have identified the optimal alternative electrical energy sources to supply certain load in an isolated region in Al-Minya City, Egypt. The load demand consists of water pumping system with a water desalination unit. Various options containing three different power sources: only DG, PV-B system, and hybrid PV-DG-B, two different sizes of reverse osmosis (RO) units; RO-250 and RO-500, two strategies of energy management; load following (LF) and cycle charging (CC), and two sizes of DG; 5 and 10 kW were taken into account. Eight attributes, including operating cost, renewable fraction, initial cost, the cost of energy, excess energy, unmet load, breakeven grid extension distance, and the amount of CO2, were used during the evaluation process. To estimate these parameters, HOMER® software was employed to perform both the simulation and optimization process. Four different weight estimation methods were considered; no priority of criteria, based on a pairwise comparisons matrix of the criteria, CRITIC-method, and entropy-based method. The main findings (output results) confirmed that the optimal option for the case study was hybrid PV-DG-B with the following specification: 5 kW DG, RO-500, and load following control strategy. Under this condition, the annual operating cost and initial costs were $ 5546 and $ 161022, respectively, whereas the cost of energy was 0.077 $/kWh. The excess energy and unmet loads were 40998 and 2371 kWh, respectively. The breakeven grid extension distance and the amount of CO2 were 3.31 km and 5171 kg per year, respectively. Compared with DG only, the amount of CO2 has been sharply reduced by 113939 kg per year.