Digital Repository for Department of Civil Engineering

Two-stage concretes, despite the fact that they have proven themselves in various types of construction, have not been studied to the same extent as traditional heavy concretes. Therefore, the article developed the composition of frame concrete with various additives in the composition of the cement-sand mortar. A comparison of the mechanical characteristics of the developed compositions with the addition of silica fume (SF) and superplasticizer (SP) in various combinations. In addition, test specimens were prepared with combinations of water/cement ratios of 0.45, 0.55, and 0.85, and cement/sand ratios of 0.5, 1, and 1.5. A total of 36 mixtures were prepared, silica fume was introduced as a partial replacement of cement in the amount of 6 wt.%. And a superplasticizer equal to 1.2 % of the cement content was added to the water. Compressive strength tests on two-stage concrete cylinders were carried out in accordance with ASTM-C873 and ASTM-C943. Tensile strength was also tested on 3 samples of each composition in accordance with the procedure described in ASTM-C496/C496M. As a result, the development of the strength of two-stage concrete for 7, 28 and 120 days was studied. It was found that the overall compressive strength of the two-stage concrete based on SF, SP and SF + SP was higher than in concrete without any additives. At the same time, the modified concrete has higher strength properties, because it provides better contact due to expansion, as well as by reducing the water-cement ratio in grout. The results obtained allow to design a cement-sand mortar capable of filling all the voids between the coarse aggregate, thereby creating a dense structure of two-stage concrete. arabic 9 English 58
Hakim S. Abdelgader(5-2019)

Since its invention by the Romans, concrete has been cast into all manner of formworks. Whether temporary or permanent, however, rigid formwork has been the traditional standard. Because concrete is the most widely used construction material, improvements in the economy of erecting concrete structures will have significant implications. One of the best opportunities for cost reduction is minimizing formwork costs—expenses that can represent about half the total cost of a concrete structure.1,2 Fabric formwork is a potential solution toward this goal. As a compounding benefit, fabric formwork can also enable the casting of structurally efficient, variable section building components.3 Taking advantage of fabric forms, however, is a joint task of concrete technology specialists, structural engineers, and architects. Fabric structures exhibit material and geometric nonlinearities when loaded, so forms must be designed based on experimentation or structural analysis using software capable of shape-finding.4,5 Education and research must focus on this barrier before the full potential of this formwork type can be realized. arabic 5 English 31
Hakim S. Abdelgader(7-2018)

Different types of concrete mixtures are used as building materials. The manufacturing process of two-stage concrete (TSC) differs from that of conventional concrete. This study investigated conventional mechanical properties derive empirical relations for estimation of the mechanical parameters of TSC and conventional concrete mixtures. TSC was used to prepare 216 specimens and conventional concrete was used to prepare 108 specimens that then were aged for 28 days. Uniaxial compression, Brazilian tensile strength, and point load tests were carried out as destructive testing. Schmidt hammer and ultrasonic pulse velocity tests were carried out as nondestructive testing. The data from testing were categorized as regression or test data. Empirical relations were derived between the parameters for the two types of concrete, and these relations were validated. It was concluded that indirect, nondestructive testing of engineering materials, including concrete, considerably increases the speed and decreases the estimation cost of determining the mechanical parameters. This method can be recommended for estimation of these mechanical parameters. arabic 13 English 97
Hakim S. Abdelgader(7-2020)

Reclaimed asphalt pavement is used as an aggregate in the cold recycling of asphalt paving mixtures. The more common method involves a process in which the asphalt pavement is recycled in-place (cold in-place recycling), CIPR. Where the reclaimed asphalt pavement is combined without heat with foamed bitumen and cement and mixed at the pavement site, at full- depth to produce a new cold mix end product. There are no universally accepted structural coefficient values for cold in-place recycled mixes (CIPR). Even though, the structural capacity of CIPR mixes considered equal to that of conventional cold mix paving material, it is not the structural is equivalent to hot mix asphalt (HMA), but is superior to gravel or crushed stone base course. The structural layer coefficient is used to calculate the structure number (SN) needed for the design of layer thicknesses. In this study, the maximum vertical compressive strain on the top of the subgrade layer was used to calculate the equivalency factor and the structural coefficient. By using the KENLAYER; the elastic layered program, the subgrade compressive strains were calculated for the typical pavement system commonly used for the major highways in Libya to get the thickness of FDR layer that would give the same compressive strain as six inches (150 mm) HMA. The thickness equivalency was taken as the ratio of the thickness of the FDR layer to that of the HMA layer of six-inch (150 mm). This was done for different FDR modulus values and different mean annual air temperatures (MAATs) which imply different resilient modulus values of HMA. As a result a relationship was developed between FDR modulus and FDR structural coefficient for various MAATs which are considered as the upper bound structural coefficient values. The conservative equation: MR= 30,000(ai/0.14)3 is considered as the lower bound values of structural coefficient. A reasonable single structural coefficient value could be specified within the specified range based on the levels of experience and quality control. A case study is used to verify the developed procedure for the design of pavement structural systems with FDR layers. arabic 7 English 51
Haifa Ali Ragab Abuhaliga(9-2014)

الملخص: تعاقب على المدينة القديمة عدة حضارات وتركت بصمة تمثلت في المباني القديمة، والتي يتطلب المحافظة عليها وصيانتها وترميمها لتبقى كثروة أثرية، ولكن من الملاحظ تدهور هذه المباني نتيجة العوامل الجوية وتدخل الإنسان مع عدم الصيانة لبعضها وصيانة البعض الأخر بطرق خاطئة كاستخدام مواد الاسمنت أو الطوب بدل من الأحجار والجير والطين المستخدم قديما ، بالإضافة إلي استيراد مواد الترميم من الخارج مما دفع بالباحثين لمحاولة إيجاد مواد محلية بديلة تكون مناسبة للترميم، ومما شجع علي ذلك توفر مادتي الجير والطين بكميات كبيرة داخل ليبيا. لذلك انطلقت هذه الدراسة بحرق عينتين من الطين تمثلت في طين يفرن وسبها لتحويلها إلى مواد بوزولانية تتفاعل مع الجير من خلال تحضير عينات من المونة المحتوية على الجير والرمل مع نسب من البوزولان تراوحت من 0% إلى 50% من وزن الرمل الطبيعي لتحديد مقاومة الضغط، وأظهرت النتائج المتحصل عليها قيم مشجعة وفتحت بابا للدراسات المستقبلية بهذا المجال، وأعطت أملاً للحصول على مواد الترميم من الخامات المحلية والاستغناء عن الاستيراد arabic 100 English 0
هيفاء علي رجب ابوحليقة(11-2020)

تتضمن هذه الورقة دراسة عن الجسور وتوظيف برنامج نظم المعلومات الجغرافية GIS لأرشفة معلومات عن هذه الجسور، فمن خلال البحث عن معلومات عن الجسور لدي مؤسسات الدولة المعنية بجسور داخل مدينة طرابلس تبين عدم وجود أي بيانات، مما تطلب حصر معظم الجسور داخل مدينة طرابلس وجمع المعلومات العامة والمتمثلة في ( الاسم، الاحداثيات، الطول، العرض، ومنطقة ربط الجسر) لعدد 51 جسر، وتم عمل دراسة تفصيلية عن ثلاث جسور واجراء فحص بصري ظاهري وجمع البيانات عن حالتها ووظائف عناصرها اذا كانت تشتغل بالشكل المطلوب وما بها من عيوب ام بصحة جيدة وبعد جمع بيانات الفحص البصري وتقييم حالة الجسور تم وضع هذه البيانات في بطاقات وربط كل البيانات التي تم جمعها في برنامج نظم المعلومات الجغرافية لأرشفتها الكترونيا ليسهل الوصول اليها في أي وقت من قبل المهتمين للحصول علي معلومات عن الجسور داخل مدينة طرابلس بطريقة سهلة وميسورة وفي اسرع وقت وتكون خطوة للاستغناء عن الارشفة الورقية. arabic 135 English 3
هيفاء علي رجب ابوحليقة(3-2020)

This research aims to experimentally evaluate the behaviour of multi-layered fibrous cementitious composites with intermediate Glass Fibre Meshes (GFM) under repeated projectile load. The impact load was subjected through a convex edge projectile needle at a low velocity on cylindrical specimens of three-layered fibrous cementitious composites, which have two different steel fibre distributions. In series A mixtures, a constant steel fibre dosage of 2.5% by volume was used. On the other hand, the fibre dosage of the outer layers was 3.0%; while it was 1.5% in the middle layer of series B mixtures. The number of intermediate GFM was the variable that distinguishes the mixtures of each series. The resistance to projectile impacts was evaluated on the basis of penetration depth, near surface distortion, weight loss, damage ratio and failure pattern. The test results showed that due to the combined effect of steel fibre and GFM, significantly lower weight losses were recorded for series A and B specimens compared with reference specimens. However, the different fibre distributions (series B) led to lower penetration depths and weight losses with less surface distortion compared with the fixed fibre distribution (series A). The reduction in the destroyed front surface area of series A specimens compared with reference specimens ranged from 27.8 to 38.1%; while that of series B specimens ranged from 34.8 to 53.4%. In addition, a simplified analytical model was introduced to predict the ejected composite mass. The model predictions were found to be in good agreement with the experimental masses. arabic 9 English 71
Hakim S. Abdelgader (1-2021)

The huge demand for concrete is predicted to upsurge due to rapid construction devel- opments. Environmental worries regarding the large amounts of carbon dioxide emanations from cement production have resulted in new ideas to develop supplemental cementing materials, aiming to decrease the cement volume required for making concrete. Palm-oil-fuel-ash (POFA) is an indus- trial byproduct derived from palm oil waste’s incineration in power plants’ electricity generation. POFA has high pozzolanic characteristics. It is highly reactive and exhibits satisfactory micro-filling ability and unique properties. POFA is commonly used as a partially-alternated binder to Portland cement materials to make POFA-based eco-efficient concrete to build building using a green material. This paper presents a review of the material source, chemical composition, clean production and short-term properties of POFA. A review of related literature provides comprehensive insights into the potential application of POFA-based eco-efficient concrete in the construction industry today. arabic 16 English 78
Hakim S. Abdelgader , (1-2021)