Abstract

Most concrete buildings face many different conditions that allow cracks to grow in concrete structural elements, causing deviations in the main stresses of the design sections that negatively affect the life of these structures. Therefore, it is necessary to focus on the restoration, strengthening, repair, strengthening and rehabilitation of these damaged concrete buildings because of the historical, cultural or functional value that these concrete structures represent that meet the needs of the contemporary infrastructure of society and to find appropriate solutions to ensure their safety and serviceability in addition to increasing their strength and solidity and extending their life. This study included the development of a cement material that uses locally sourced components in addition to steel fibers and some chemical additives to produce a material that reduces the various challenges associated with this task. The results were successful, in addition to the fact that the study opened other research horizons in this aspect to increase research on the best and most appropriate effective and sustainable solutions. In this study, a set of laboratory tests were conducted that were relied upon for the research, and included testing the basic materials: cement, fine sand, water, super plasticizer additives, and silica dust, and performing a compressive strength test on regular concrete samples and samples of cement mixtures improved by adding steel fibers, the super plasticizer, and silica dust. Based on the results obtained, the study presents the possibility of obtaining an improved cement mixture that can be used in rehabilitating concrete structures and structures. The study also included some recommendations that can be used to further develop the improved cement mixture using a group of additives present within the Libyan state.

Abstract

Concrete is the main material for implementing concrete buildings and infrastructure projects in most regions of the world. During the past years, it has witnessed a great development that contributed to the construction of concrete buildings of various types ]1[ . Despite the development witnessed by the stages of concrete manufacturing, there are still some problems facing the stages of its implementation. This research reviews the study of the effect of hot climate (desert) on the mechanical properties of concrete mixtures, which included of compressive strength, indirect tensile strength and bending strength by doing laboratory tests were conducted on ordinary concrete with comparison with the test results of improved concrete added to silica fume and superplasticizers during (0, 45, 90) daily thermal cycles. The study used ratio of additives in the normal mix (cement: aggregate: sand: water) is (1: 2.5: 2: 0.55) % of the cement weight and the ratio of additives in the improved mix (cement: aggregate: sand: water: Sika Fume: superplasticizers) is (1: 2.2: 1.3: 0.22: 0.1: 0.18) % of the cement weight. After the mixing process, the samples were immersed in water for 28 days and then placed in electric ovens for (45, 90) thermal cycles. Then, the compressive strength test, indirect tensile strength test and flexural strength test were conducted for the normal mix and improved mix samples. The compressive strength of the improved concrete recorded much better values than the compressive strength values of the normal concrete during all stages of the thermal cycles. Also the results of indirect tensile strength reflected a significant advantage for the improved concrete over the normal concrete during all stages of the daily thermal cycles. Moreover the test results rapture stress showed that the improved concrete has better resistance to bending comparing with the bending resistance of normal concrete during the daily thermal cycles. The process of adding improved materials to the concrete mix reflected achieving amazing properties by developing the concrete’s behavior in resisting loads and hot climatic conditions. 

Abstract

In light of the increasing need to enhance the performance of construction materials, traditional concrete poses several challenges, including low tensile strength, limited aesthetic qualities, and poor interaction with environmental factors such as natural lighting. With the advancement of construction technologies and growing interest in sustainability and innovative architectural design, translucent concrete reinforced with optical fibers has emerged as a modern solution that combines structural durability with light transmittance. This fusion enhances both the functional and aesthetic aspects of conventional concrete. This study aims to investigate the effect of adding plastic optical fibers (PMMA) on the compressive strength and light transmittance of concrete mixes. Three concrete mixtures were prepared using PMMA optical fibers at proportions (0% ,7.2% and 14.4%) of the cement weight, serving as a partial replacement for coarse aggregates. These were compared with a conventional reference mix. Additionally, the fiber layout was altered to an interlaced distribution pattern to enhance load and stress transfer within the matrix—not only light conduction. Compressive strength and light transmittance tests were conducted to evaluate the performance of each mix. The results indicated that the incorporation of optical fibers significantly improved light transmittance, with higher fiber content resulting in greater translucency. This feature supports the use of natural lighting in interior spaces and reduces dependency on artificial lighting. From a mechanical perspective, the mix containing 7.2% optical fibers showed an increase of 4.02% in compressive strength compared to the reference mix, indicating that a moderate fiber concentration can improve internal cohesion. However, the mix with 14.4% fiber content experienced a 39.35% reduction in compressive strength due to fiber clustering, which led to segregation and void formation within the concrete structure. The study concludes that translucent concrete reinforced with optical fibers represents an effective balance between mechanical performance and aesthetic functionality. It is a promising material for modern civil engineering applications, especially in structures where visual appeal and energy efficiency are prioritized. The research recommends further refinement of fiber distribution techniques to avoid segregation and to fully exploit the properties of optical fibers. Furthermore, this innovative concrete type holds great potential for advanced architectural and structural applications such as interior partitions and building façades, contributing to energy-efficient, sustainable, and visually compelling built environments.

: تُعتبر التقاطعات المرورية من العناصر الأساسية في أي نظام مروري، حيث تلعب دورًا حيويًا في تنظيم حركة المرور وتوجيه المركبات وتتمثل أهمية هذه التقاطعات في كونها النقاط التي تتقاطع فيها طرق مختلفة، مما يسهل الحركة بين المناطق. ومع ذلك، يمكن أن يؤدي تصميم التقاطعات بشكل غير مناسب إلى مشكلات كبيرة، مثل الازدحام وأوقات الانتظار الطويلة، مما يؤثر سلبًا على تجربة السائقين وفاعلية النظام المروري. عندما تكون التقاطعات غير مصممة بشكل جيد، فإنها تؤدي إلى تدفق حركة مرور غير منتظم، مما يستدعي الحاجة إلى دراسات علمية دقيقة لتحليل تدفق حركة المرور، يجب أن تعتمد هذه الدراسات على أسس علمية سليمة لفهم العلاقة بين تصميم التقاطعات وأداء حركة المرور. يمكن أن تكون هناك حلول تشغيلية غير مكلفة، مثل تحسين الإشارات الضوئية أو تغيير أنماط الحركة، مما يسهم في تحسين الكفاءة.

من خلال مراجعة الدراسات السابقة، يتضح أن هناك اهتمامًا متزايدًا بتقييم تأثير التقاطعات على حركة المرور باستخدام البرامج الحاسوبية لذلك جاءت هذه الدراسة لاستعرض اهم هذه الدراسات والتركيز على أهم النقاط الأساسية التي تبرز كيفية تحسين أداء هذه التقاطعات وزيادة كفاءة الشبكة المرورية.

 وتتناول هذه الورقة بعض الدراسات المتعلقة بالتقاطعات وتأثيراتها على حركة المرور، مع التركيز على استخدام البرامج الحاسوبية لتقييم أدائها، وتشمل هذه الدراسات تحليل الأداء المروري، ودراسة كيفية تأثير تصميم التقاطعات وإشارات المرور على كفاءة الحركة ويتم استخدام برامج مثل "Synchro" و"VISSIM" و"SIDRA"و" HCS" لتقييم مستوى الخدمة وزمن التأخير في تقاطعات مختلفة، كما تُستخدم تقنيات المحاكاة لحل المشكلات المرورية وتحسين تدفق الحركة، وتقوم بعض الدراسات بمقارنة بين هذه البرامج لتحديد تأثيراتها المختلفة على حركة المرور.

 Abstract

Concrete is the main material for implementing concrete buildings and infrastructure projects in most regions of the world. During the past years, it has witnessed a great development that contributed to the construction of concrete buildings of various types [ 1 ] .Despite the development witnessed by the stages of concrete manufacturing, there are still some problems facing the stages of its implementation. This research reviews the study of the effect of hot climate (desert) on the mechanical properties of concrete mixtures, which included of compressive strength, indirect tensile strength and bending strength by doing laboratory tests were conducted on ordinary concrete with comparison with the test results of improved concrete added to silica fume and superplasticizers during (0, 45, 90) daily thermal cycles. The study used ratio of additives in the normal mix (cement: aggregate: sand: water) is (1: 2.5: 2: 0.55) % of the cement weight and the ratio of additives in the improved mix (cement: aggregate: sand: water: Sika Fume: superplasticizers) is (1: 2.2: 1.3: 0.22: 0.1: 0.18) % of the cement weight. After the mixing process, the samples were immersed in water for 28 days and then placed in electric ovens for (45, 90) thermal cycles. Then, the compressive strength test, indirect tensile strength test and flexural strength test were conducted for the normal mix and improved mix samples.The compressive strength of the improved concrete recorded much better values than the compressive strength values of the normal concrete during all stages of the thermal cycles. Also the results of indirect tensile strength reflected a significant advantage for the improved concrete over the normal concrete during all stages of the daily thermal cycles. More over the test results rapture stress showed that the improved concrete has better resistance to bending comparing with the bending resistance of normal concrete during the daily thermal cycles. The process of adding improved materials to the concrete mix reflected achieving amazing properties by developing the concrete’s behavior in resisting loads and hot climatic conditions.