استهدف البحث جزء من منطقة يفرن لدراسة مدى تأثير المكونات الطبيعية للخزانات الجوفية على نوعية وجودة المياه المستخدمة في أغراض الشرب. ونظراً لمحدودية الدراسات التي تمت على المنطقة، كذلك اعتماد سكان المنطقة بشكل شبه كلي على المياه الجوفية رغم محدوديتها في تلبية المتطلبات المائية لسد الاحتياجات في شتى الأغراض. كل تلك الأسباب جعلتنا نتخذ من منطقة يفرن موضوعاً للدراسة. شملت الدراسة كل الآبار المخصصة للشرب تقريباً في منطقة يفرن والبالغ عددها 23 بئراً موزعة ملكيتها بين القطاع العام والخاص، حيث تمثلت هذه الدراسة بأخذ عينات من مياه الآبار المستهدفة وإجراء التحاليل الكيميائية اللازمة لها (المواد الكيميائية الطبيعية ) والتي لها تأثير على صلاحية المياه للشرب وذلك لمعرفة مدى تأثر المياه بالأوساط المتواجدة فيها وتقييم جودتها من الناحية الكيميائية وذلك بمقارنتها بالمواصفات القياسية الليبية لمياه الشرب،حيث تمثلت الدراسة في معرفة تركيز المواد الصلبة الذائبة والعسر الكلي وبعض الايونات الموجبة والسالبة المتواجدة في المياه الجوفية في منطقة يفرن، ومن ثم مقارنتها بالمواصفة القياسية الليبية، حيث تمثلت النتائج النهائية وجود 18 بئراً مخالف للمواصفة القياسية الليبية لمياه الشرب. حيث تجاوزت فيها تركيز العناصر والمركبات الكيميائية( الايونات الموجبة والسالبة ) الحد الأقصى المسموح به وفق المواصفات القياسية الليبية لمياه الشرب وبناءً على هذه النتائج تم اقتراح احد الحلول المناسبة لمعالجتها
عيادة امحمد ابوعجيلة (2010)

Two-stage concrete (TSC) is a special type of concrete that themethod of its construction and implementation is different fromconventional one. In TSC, coarse aggregate particles are first placed in the formwork and voids between themare subsequently injected with a special cementations mixture. TSC has been successfully used in many applications, such as underwater construction, casting concrete sections congested with reinforcement and concrete repair. Coarse aggregate forms about 60% of the total volume of TSC, while coarse aggregate forms about 40% of the total volume of conventional concrete. In TSC stresses are transferred through contact areas between coarse aggregate particles. In this paper coarse aggregate size influence on strength parameters of TSC and comparing it with conventional concrete is done (by uniaxial compressive strength test and Brazilian tensile strength test). According to results of tests in this paper, the TSC with finest grain of coarse aggregate has higher compressive and tensile strength, higher modulus of elasticity and less Poisson’s ratio from conventional concrete. arabic 11 English 66
Hakim Salem Abdelgader Abdelgader (3-2019)

Alkali-activated materials (AAMs) received broad recognition from numerous researchers worldwide and may have potential applications in modern construction. The combined use of AAM and steel fibers are superior to typical binder systems because the matrix and fibers exhibit superior bond strength. The results obtained by various authors have shown that good dispersion of the fibers ensures good interaction between the fibers and the AAM matrix. The tensile strength of FR-AAC is superior to that of Ordinary Portland cement (OPC)-based materials, with the addition of silica fume (SF) being particularly remarkable. However, the tensile strength of fiber-reinforced alkali-activated concrete (FR-AAC) decreases with increasing fiber length. The bond strength increases with the increasing grade of concrete, the roughness of interface, and the solution's strength activated by alkalis. Regardless of fiber type, AAC's modulus of elasticity is linearly correlated with compressive strength. Fibers can affect the modulus of concrete due to the stiffness of the fiber and the porosity of the composite. Poisson's ratio for AAC corresponded to the ASTM C469-14 standard (about 0.22) and decreased to about 0.15–0.21 with silica fume addition. There are limited resources for the experimental Poisson's ratio and it is only estimated using the predictive equations available. Therefore, it is necessary to conduct additional experimental studies to estimate Poisson's ratios for FR-AAC composites. Retention of 59% and 44% in flexural strength during exposure at 800 °C and 1050 °C was observed in the FR-AAC stainless steel composite, and the chopped alumina fibers achieved higher yield strength at these temperatures. For FA-based AAC mortars with 1% SF with a hooked end, activated with a solution of NaOH and sodium silicate, an increase in the number of bends increased the bond strength, load pull-out and maximum pull-out strength. Autogenous shrinkage and drying shrinkage increase with higher silicate content, while shrinkage decreases with higher NaOH concentration. Relatively little research has been completed on FR-AAC in terms of durability or different environmental conditions. In addition, trends of development research toward the broad understanding regarding the application possibilities of FR-AAC as appropriate concrete materials for developing robust and green concrete composites for modern construction were extensively reviewed.
Hakim S. Abdelgader (1-2022)