Although several studies have been conducted to evaluate the impact response of concrete using the American Concrete Institute (ACI) 544-2R falling mass impact test, the variations in test results are the main drawback of this testing method. This study aims to reduce the variations in experimental impact test results by introducing two simple test setup modifications; (1) using coarse or fine aggregate bed- ding as an alternative to the steel base plate, (2) the use of line or cross-notched specimens with a line or cross-load distributing steel plate. One hundred thirty-five cylindrical discs were prepared with Preplaced Aggregate Fibrous Concrete (PAFC) and Slurry Infiltrated Fibrous Concrete (SIFCON), tested in nine groups to assess the proposed modified techniques. Steel hooked-end (2.5%) and macro polypropylene (8.0%) fibers were used to develop PAFC and SIFCON, respectively. The research findings revealed that using aggregate bedding increased the impact resistance by 38 to 429% for no-notch spec- imens and up to 283% for notched specimens. The presence of notches reduced the total energy absorbed by the bedding material. For instance, the specimens with a line notch and sand bedding exhibited 15 to 51% lower failure impact numbers than their corresponding no-notch specimens. Considering surface- notched specimens and aggregate bedding led to a lower scattering of the impact test results, while the line-notched specimens exhibited lower average scattering than the cross and no-notched specimens. In general, a percentage decrease in the coefficient of variation of 30 to 74% was attained for specimens with bedding and/or surface notch compared to reference specimens. arabic 16 English 111
Hakim Salem Abdelgader Abdelgader (9-2021)

Building and infrastructure damages, such as tunnels, have become a more important issue because of the continuous expansion of rural and urban constructions. It is well-known that when high-strength concretes (HSCs) are exposed to high temperatures; it is more likely to experience explosive fire-induced spalling than conventional strength concrete. Spalling might result in catastrophic loss of life and damage to nearby critical infrastructure. The exposure of reinforcement bars to elevated temperature, decreased permeability, higher density, moisture transfer, and brittleness of the HSC contribute to spalling. The concrete on a structural member's surface may be violently ripped apart by a high and fast rising temperature during a fire. Despite being a non-combustible material, the physics-chemo-mechanical properties of concrete deteriorate when subject to high temperatures. The magnitude and duration of a fire in a concrete structure define the severity of the fire. The resistance to fire spalling of HSCs under different fire conditions, extremes, and tendencies must be explored urgently. Cementitious materials exhibited a positive impact as an alternative to cement in HSC because they are known as environmentally friendly concrete materials with superior fire-resistant properties. In addition, the inclusion of fibers as an additive reinforcement is adopted to prevent and mitigate fire spalling in HSCs. Therefore, the establishment of appropriate fire-safety measures is a fundamental requirement in building design to ensure the safety of its inhabitants. While the process of fire spalling for HSC during a fire has not yet been completely understood. For this reason, a critical literature study on recent developments in HSC fire-resistance performance should be conducted to determine the present fire spalling behavior of HSC in the event of high temperatures and/or a fire. This article systematically reviews the mechanisms, influential factors, and types of fire spalling. This literature also reviews the behavior, fire spalling modelling, and strategies to prevent spalling in HSC applications. Given the advantages of the research subject, several hotspot research topics for scientific investigations are also suggested to facilitate the widespread use of HSCs in advanced construction applications.
Hakim S. Abdelgader (5-2022)

تمثل الطرق العمود الفقري للبلاد والذي تتمحور حوله وحدة البلاد ونموها وتطورها ، ومما لاشك فيه بأن وجود شبكة متطورة من الطرق في الدولة يمكنها من تحقيق أهدافها وسياساتها المختلفة، فالتقدم في تخطيط وتنفيذ الطرق يعمل على تغيير نمط الحياة ورفع مستوى المعيشة ويساهم في تطور ونمو المجتمعات .تناولت هذه الدراسة البحث في موضوع عوامل ومعايير التصميم الهندسي للطرق ، وأستعرضت كلا من إعتبارات التصميم القديمة والعوامل المطورة لها ، والإعتبارات الأساسية الحديثة للتصميم، كما تطرقت إلى العناصر الأساسية والثانوية للتصميم الهندسي للطرق ، وقدمت لمحة عن مدى تأثير تصميم الطريق على سلامة المرور .وتم عمل مقارنة بين معايير التصميم الهندسي للطرق الحضرية مأخوذة من أربع أدلة تصميم مختلفة، والأدلة على التوالي هي :دليل التصميم الهندسي للطرق لولاية أريزونا الأمريكية ، ودليل التصميم الهندسي للطرق لجنوب أفريقيا ، ودليل التصميم الهندسي للطرق للسعودية، ومشروع إعداد دليل معايير التصاميم الهندسية لشبكة الطرق في ليبيا (الجزء الخاص بالطرق الحضرية) ، وأعطت تقييم عن المعايير المطبقة في ليبيا من خلال أمثلة لبعض مقاطع الطرق القائمة في مدينة طرابلس، كما ناقشت بعض المشاكل الناتجة عن عيوب معايير التصميم والتخطيط في المدينة ، وأهم ما قدم من مقترحات لمعالجتها .كما تم عمل دراسة تحليلية ( إستبيان ) كان الغرض منه التوصل إلى مجموعة من الأهداف وهي كالتالي:التعرف على نشاط الدولة الليبية في أعمال تصميم الطرق من عدمه .انطلاقا من أي مرجعية يتم تصميم الطرق في ليبيا ؟مدى اختلاف معايير التصميم باختلاف الفترات الزمنية التي تم فيها التصميم .مدى مواكبة معايير التصميم المستخدمة حالياً في ليبيا للتطور العمراني .مدى تأثير معايير التصميم على السلامة العامة لكل من الركاب والمشاة والبيئة .وختاما وبإستخدام كلا من النتائج المستخلصة من مراجعة مسودة مشروع إعداد دليل معايير التصاميم الهندسية لشبكة الطرق في ليبيا والمقارنة التي تمت بينها- المسودة – وبين الأدلة الأخرى، والنتائج المستخلصة من مراجعة مسودة مشروع إعداد دليل معايير التصاميم الهندسية لشبكة الطرق في ليبيا ومطابقتها للنتائج المتحصل عليها من الدراسة التحليلية (الاستبيان) ، خلُصت الدراسة إلى إستنتاجات وتوصيات يُرى أنها جديرة بكل إهتمام . Abstract Roads constitute the backbone around which revolves the country's unity , growth and development .Undoubtedly the presence of a developed network of roads in the country enables it to achieve its objectives and different policies , progress in roads is conducive to changing the lifestyle , raising the standard of living and contributing to the development and growth of societies.This study researched the factors and engineering design standards for roads and reviewed both the old design considerations and developing factors and basic considerations for modern design, and also addressed the primary and secondary elements of geometric design of roads and provided an overview of the impact of road design on traffic safety. Acomparison was conducted of engineering design criteria for urban roads taken from four different design guides and are respectively: Engineering design manual for roads of the U.S. state of Arizona, Engineering design manual for roads of South Africa, Engineering design manual for roads of Saudi Arabia, The project for preparing a manual of standards of engineering designs for the roads network in Libya (the section on urban roads). The study gave an assessment of the criteria applied in Libya through the examples of some sections of existing roads in the city of Tripoli, also discussed some of the problems resulting from defects in design standards and planning in the city and most important submitted proposals to address such defects.An analytical study ( questionnaire) was designed to reach the following set of goals:Identification of Libya State activity in the works of road design.What is the reference of road design in Libya?Variation of design standards for different time periods in which the design was developed.To what extent are the design criteria – currently used in Libya – are in pace with urban development?Extent of impact of design criteria on public safety for passengers,pedestrians and the environment.In conclusion, by applying the results extracted from reviewing the draft of the project for preparing the manual of criteria of engineering designs for the roads network in Libya and the conducted comparison between this draft and the other evidence and the extracted results from reviewing the draft of the project for preparing the manual of criteria of engineering designs for the roads network in Libya and the subsequent matching of the results obtained from the analytical study (questionnaire), the study reached conclusions and recommendations it deems worthwhile of due attention.
هالة محمد دحيم (2012)